Deborah N. Aguilera
Title: Spin-one color superconductivity in compact stars?
Abstract: We study two spin-one color superconducting phases of two-flavor quark matter in a nonlocal chiral model and discuss whether these could be found in the interior of compact stars. The pairing patterns we consider are the anisotropic blue color paring besides the usual two color superconducting matter (2SCb), in which red and green colors are paired, and the color-spin locking phase (CSL). The effect of nonlocality on the gaps is rather large and the pairings exhibit a strong dependence on the form factor of the interaction, especially in the low density region. The application of these small spin-one condensates for compact stars is analyzed: the early onset of quark matter of the nonlocal models may help to stabilize hybrid star configurations. While the anisotropic blue quark pairing does not survive a big asymmetry in the flavor space as imposed by the charge neutrality condition, the CSL-condensate is particularly interesting for compact star cooling applications at a first glance since it is flavor symmetric. Nevertheless, the nonlocality seems to make the diquark pairing gaps in the CSL phase too small to be brought in accordance with recent estimates from cooling phenomenology. Therefore, if nonlocal effects are taken into account, both phases seem to be unlikely to occur in the interior of compact stars.

Alexey Aksenov
Title: Structure of pair winds from compact objects with an application to the emission from hot bare strange stars
Abstract: A stationary outflowing wind from the compact star consisting of electron-positron pairs and photons is studied. We do not not assume the thermal equilibrium, and include two-body processes (ee ↔ ee, γe ↔ γe, e⁺e^- ↔ γγ) which occur in a such wind together with their radiative three-body variants (ee ↔ eeγ, γe ↔ γeγ, e⁺e^- ↔ γγγ). In compare with previous works (Aksenov, A.G., Milgrom, M., Usov, V.V. 2004, ApJ, 609, 363; Aksenov, A.G., Milgrom, M., Usov, V.V. 2005, ApJ, 632, 567) now we considered also the case of large luminosities. As an example, the wind injection source is a hot, bare, strange star. Such stars are thought to be powerful sources of hard X-ray photons and e^± pairs created by the Coulomb barrier at the quark surface. We also present a new, finite-difference scheme for solving the general relativistic kinetic Boltzmann equations for pairs and photons for the spherically symmetrical case. Using this method we study the kinetics of the wind particles and the emerging emission for the energy injection rate in pairs up to luminosities 10³⁹ ergs s^-1 when of the gravitation is important. At high luminosities we used the hydrodynamical approximation. The influence of nonthermal photons radiated by the star is also discussed.

Ali Alpar
Title: Dim Isolated Neutron Stars, Cooling and Energy Dissipation
Abstract: Cooling histories of isolated neutron stars will be discussed with possible contributions of energy dissipation accompanying spindown torques due to dipole, magnetar and disk torques.

Nils Andersson
Title: Modelling the dynamics of superfluid neutron stars
Abstract:The superfluid nature of the core has profound implications for the dynamical evolution of a neutron star, giving rise to the pulsar glitches and also providing key dissipation mechanisms affecting both potential free precession and the damping of core oscillation modes. I will discuss the issues involved in model this complicated multi-fluid problem and discuss the astrophysical implications of the current models.

Debades Bandyopadhyay
Title: Exotic bulk viscosity and its influence on neutron star r-modes
Abstract:We investigate the effect of exotic matter in particular, hyperon matter on neutron star properties such as equation of state (EoS), mass-radius relationship and bulk viscosity. Here we construct equations of state within the framework of a relativistic field theoretical model. As large number of hyperons may be produced in dense matter, hyperon-hyperon interaction is important and included in this model. Hyperon-hyperon interaction makes the EoS softer resulting in a smaller maximum mass neutron star compared with the case without the interaction. Next we compute the coefficient of bulk viscosity due to nonleptonic weak process including Λ hyperons. It is found that the interacting hyperon matter affects the bulk viscosity coefficient and the corresponding damping time scale significantly. Further, we investigate the role of the bulk viscosity on gravitational radiation driven r-mode instability for a neutron star of given mass and temperature and find that the instability is more effectively suppressed for the case with hyperon-hyperon interaction compared with the situation without the interaction.

Matthew G. Baring (M. G. Baring, A. K. Harding (NASA/GSFC))
Title: Modeling the Hard X-ray Components of Anomalous X-ray Pulsars
Abstract: A significant new development in the study of Anomalous X-ray Pulsars (AXPs) has been the recent discovery by INTEGRAL, with supporting archival data from RXTE, of flat, hard X-ray components in three AXPs. These non-thermal spectral components differ dramatically from the steeper quasi-power-law tails seen in the classic X-ray band in these sources. A prime candidate mechanism for generating this new component is resonant, magnetic Compton upscattering. This process is very efficient in the strong magnetic fields present in AXPs. In this paper we explore an inner magnetospheric model for upscattering of surface thermal X-rays in AXPs, to investigate whether such resonant upscattering can explain the 10-50 keV spectra seen by INTEGRAL. Non-thermal electrons are injected in the emission region at a specified altiture and magnetic colatitude, and their rapid cooling due to the resonant scattering is tracked. Their resulting emission is computed using both kinetic equation and Monte Carlo simulation techniques. The latter method enables the modeling of radiation and electron propagation and interaction in a full magnetospheric geometry. As we use the relativistic scattering cross section, Klein-Nishina reductions are influential in determining the photon spectra and electron cooling rates. Results are strongly dependent on the locale of electron injection, and potential observational diagnostics on surface field geometry and atmospheric radiation anisotropy are identified.

Werner Becker
Title: X-ray emission properties of old pulsars
Abstract: Young and middle aged neutron stars, which emit strong pulsed non-thermal and/or surface hot-spot plus cooling emission, were studied reasonable well by previous X-ray observatories. In contrast, most old radio pulsars were too faint for a detailed examination of their X-ray emission and are clearly sources which required the sensitivity of Chandra and XMM-Newton to be studied in sufficient detail. In my talk I will review recent results on the X-ray emission properties of old pulsars and report on a study of the diffuse trail like emission components found in PSR B1929+10, B0355+54 and B2226+65.

Andrei M Beloborodov (A.M. Beloborodov, C. Thompson)
Title: Corona of Magnetars
Abstract: We develop a theoretical model that explains formation of hot coronae around strongly magnetized neutron stars — magnetars. The starquakes of magnetars twist their external magnetosphere and it becomes non-potential, i.e., threaded by electric currents. Once twisted, the magnetosphere cannot untwist quickly because of its huge self-induction. The induced electric field lifts particles from the stellar surface, accelerates them, and initiates avalanches of pair creation in the magnetosphere. The created plasma maintains the current demanded by curl B and regulates the self-induction e.m.f. by screening. This corona persists in dynamic equilibrium: it is continually lost to the stellar surface on the light-crossing time ~0.1 ms and replenished with new particles. In essence, the twisted magnetosphere acts as an accelerator that converts the energy of the toroidal magnetic field to particle kinetic energy. Using a direct numerical experiment, we show that the corona self-organizes quickly (on a ms timescale) into a quasi-steady state with voltage ~1 GeV. The heating rate of the corona is about 10³⁶ erg/s, in agreement with the observed persistent, high-energy output of magnetars. We deduce that a static twist that is suddenly implanted into the magnetosphere will decay on a timescale of 1-10 yrs. The coronal plasma is the probable source of persistent nonthermal radiation observed in various bands, from IR to gamma-rays.

Andrei M Beloborodov (A.M. Beloborodov, M.A. Ruderman)
Title: Processing of surface X-ray emission by electron-positron envelopes around young neutron stars
Abstract: Rapidly spinning neutron stars produce high-energy gamma-rays that sustain electron-positron filled inner magnetospheres. These e+- envelopes are optically thick to X-rays emitted by the star (because of cyclotron-resonance scattering) and prevent direct observation of the stellar surface. The scattered radiation has much less phase modulation and spectral structure than the original emission. It contains the same number of X-ray photons but the average photon energy may be significantly increased. If upscattered X-rays are interpreted as a quasi-thermal component at a temperature greater than that of the initial surface emission, the inferred blackbody emission area is reduced. The magnitude of this effect depends on details of the gamma-ray emission geometry, accelerator locations, and magnetic field structure near the neutron star. If the post-creation e+- flow along magnetic field lines in the inner magnetosphere is nearly relativistic, this area reduction could be by up to a few orders of magnitude. Continually created pairs also produce a non-thermal synchrotron emission component which should peak above 20 kev, well above the thermal component.

Grigory Beskin
Title: Search for fast optical activity of SGR 1806-20 at the SAO RAS 6-m telescope.
Abstract: Beskin G.M., Debur V.G., Plokhotnichenko, V.L., Karpov, S.V., Pozanenko, A., Hurley, K. The region of SGR 1806-20 localization was observed during its gamma-ray activity in 2001 and 2004. The observations has been performed on 6-meter telescope of Special Astrophysical Observatory, Russia, using the panoramic photon counter with 1 us temporal resolution. The search for different kinds of variability (stochastic and periodic) is performed on 10^-6 - 10 s time scale, and its results are compared with corresponding x-ray activity properties. Implications for the models of SGR are presented.

Anton V. Biryukov
Title: On the peculiarities in the rotational frequency evolution of isolated neutron stars.
Abstract: The results of the statistical investigation of dependence between the first and second derivative of the rotational frequency of isolated pulsars are reported. In this work precise timing parameters for more than 250 pulsars provided by several groups over the last few years are used. A strong correlation (r ~ 0.90) between values of the first and second derivatives was discovered. This correlation is valid for both positive and negative values of the second derivative. The observed correlation is apparently related to the complex (oscillating) law of INS rotational frequency evolution. Unlike the well-known pulsar timing noise (“red noise”), these oscillations have longer timescales and are common for all pulsars. But both phenomena may be of the same physical origin. Such peculiarities explain the observed extreme values of the braking index, allow to determine the average law of INS period evolution, define more accurately the pulsars’ age scale and give additional information about INS interior.

Sergei Vladimirovich Bogovalov
Title: The magnetic colimation of the pulsar winds in the preshock and post shock regions.
Abstract: Magnetic collimation of the pulsar winds drastically differs in the regions upstream the termination shock wave and downstream the shock. In the preshock region the collimation is very weak and can be neglected. In the post shock region the collimation results into formation of jet-like features observed in the Crab and Vela nebulas.

Marta Burgay
Title:Search for Radio Pulsations in AXPs Abstract: We report on the analysis of deep observations of four AXPs performed at 1.4 GHz with the Parkes radio telescope. No radio pulsation was found down to a limit of ∼ 0.2 mJy.

Fiorella Burgio
Title: A microscopic equation of state for protoneutron stars Abstract: The structure of (proto)-neutron stars is studied within the Brueckner-Bethe-Goldstone many-body theory. Purely nucleonic and hyperonic (proto)-neutron stars are considered. It is found that both temperature effects and neutrino trapping are essential in determining the value of the maximum mass. Preliminary results on the effects of a hadron-quark phase transition will be presented.

Mark Cropper
Title: XMM-Newton Observations of the Isolated Neutron Star RBS 1774
Abstract: We report on the results of a deep XMM-Newton observation of RBS 1774, the most recent dim isolated neutron star candidate found in the ROSAT archive data. Spectral and timing analysis of the high-quality pn and MOS data confirm the association of this source with an isolated neutron star. The spectrum is thermal and blackbody-like, and there is evidence at a significance level >4 sigma that the source is an X-ray pulsar with a spin period of 9.437 s. Spectral fitting reveals the presence of an absorption feature at ∼0.7 keV, but at this level data do not have enough resolution to allow us to discriminate between an absorption line or an edge. We compare the newly measured properties of RBS 1774 with those of other known dim isolated neutron stars and discuss possible interpretations for the absorption feature.

Simone Dall'Osso
Title: Constraining the emission of GW from newborn magnetars
Abstract: I will discuss a new argument that allows to set contraints on the emission of Gravitational Waves from newborn magnetars. Using a toy model, with realistic physical assumptions, I describe the spin evolution of a magnetar in the first days after its formation, subject to both magnetic dipole and GW torques. Based on this, the amount of energy emitted via Gravitational Waves as a function of the initial spin and magnetic field can be calculated. Finally, I discuss an observational test that can be used to put constraints on the initial parameters of known magnetar candidates

Tracey DeLaney
Title: Constraints on Neutron Star Cooling using Chandra Observations of PSR B1509-58 and PSR B1951+32
Abstract: The cooling of young neutron stars is poorly understood because of our lack of knowledge on the physics of matter at ultrahigh densities. Temperature measurements for neutron stars of different ages thus provide strong constraints on models for structure of their interiors. We have used high-time resolution Chandra HRC observations of PSR B1509-58 (P=150 ms) and PSR B1951+32 (P=39 ms) to measure their off-pulse emission and obtain upper limits on their surface temperatures. The high spatial resolution of Chandra allows us to separate the pulsars from their surrounding nebulae. PSR B1509-58 shows significant off-pulse emission similar to the Crab pulsar and possibly indicates the presence of unpulsed nonthermal emission. We compare our temperature limits to other pulsars and use them to provide constraints on neutron star cooling models.

Andrea De Luca
Title: The puzzling compact X-ray source in RCW103
Abstract: 1E 161348-5055 is a compact, radio quiet X-ray source lying at the center of the 2000 years old supernova remnant RCW103. Its original identification as an isolated neutron star was questioned in recent years owing to its long-term X-ray flux variations. We will describe the results of our XMM-Newton observations, which, together with previous Chandra observations, settle the case for a unique phenomenology, dramatically evolving on a few years time scale. While some properties of 1E 161348-5055 are reminiscent of low-mass accreting systems, several striking similarities with active magnetars' behaviour are apparent. Different scenarios will be discussed in view of the source unique phenomenology.

Peter R. den Hartog
Title: AXP 4U 0142+61: New INTEGRAL results and the first simultaneous multi-frequency observation campaign
Abstract: Until recently Anomalous X-ray Pulsars (AXPs) were known as soft X-ray emitters. This has changed drastically since the discovery of hard X-ray emission (>10 keV) from three AXPs by INTEGRAL (Molkov et al. 2004, Revnivtsev et al. 2004 and den Hartog et al. 2004; 2006). Kuiper et al. (2004; 2006) discovered pulsed emission above 10 keV from four AXPs using RXTE (PCA and HEXTE) data. The power-law like spectra (20-150 keV) are very hard with photon indices > ∼1.0 and the derived luminosities are 2-3 orders of magnitude above the rotational energy losses. In June/July 2005 the first (quasi) simultaneous multi-frequency observation program was performed on AXP 4U 0142+61. This AXP has been observed in hard X-rays/soft gamma rays with INTEGRAL, in soft X-rays with SWIFT XRT and RXTE, in Optical and Near Infrared with Gemini North and in the radio band with the Westerbork Synthesis Radio Telescope. The newly obtained INTEGRAL data (1 Ms) are combined with existing data, mainly from deep INTEGRAL campaigns on the Cassiopeia region, in order to reach a very deep hard X-ray/ soft gamma-ray look at 4U 0142+61. In this talk I will present these new INTEGRAL results and the first results of the multi-frequency campaign of 4U 0142+61.

Rim Dib
Title: 10 Years of RXTE Monitoring of Anomalous X-ray Pulsar 4U0142+61
Abstract: We report on 10 years of monitoring of the 8.7-s Anomalous X-ray Pulsar 4U0142+61 using the Rossi X-Ray Timing Explorer (RXTE). This pulsar has shown continued timing stability since 2000: the RMS phase residual for a spin-down model which includes nu, nudot, and nuddot is 1.9%. We also report that the source's pulse profile has been evolving in the past 5.5 years, such that the dip of emission between its two peaks has been getting shallower since 2000, almost as if it is recovering to its pre-2000 morphology, in which there was no clear distinction between the peaks. Further analysis showed that the profile variations are seen in the 2-4keV band but not in the 6-8keV band.

Richard Dodson (D. Lewis, R. Dodson, P. McCulloch)
Title: Vela: 20 years of timing in the radio
Abstract: The Mount Pleasant Observatory, Hobart, run by the University of Tasmania, Australia, has been timing the Vela pulsar for more than 21 years. Recently it has been monitoring Vela for eighteen hours a day, waiting to catch it in the act of ‘glitching’. It provided the highest time resolution of any glitch for the event in January 2000, which revealed an extremely short–term decay component (Dodson, McCulloch, & Lewis 2002). This was also detected in the July 2004 glitch. This decay component will provide constraints to the nature of the coupling of the stellar crust to the liquid interior.

Martin Durant
Title: Intrinsic spectra of magnetars
Abstract: Magnetars (Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars) have been very exciting to research as of late, with their many and varied high-energy phenomena. They promise, with extreme magnetic, electrodynamic, energy, density and gravitational properties, to be ideal natural laboratories for unlocking the secrets of fundamental physics. Using direct measurements of photoelectric absorption edges, I derive the intrinsic spectra for the Anomalous Xray Pulsars. Particularly for the brightest source, 4U0142+61, the correction is highly significant, and thus may alter the interpretation of other recent results for this source. To be emphasised, is that this is an empirical method with the minimum of assumptions, as is appropriate for these beguiling sources, the behaviour of which has mystifies astronomers for over a decade.

David Eichler
Title: Transient Heating and Cooling of Neutron Stars
Abstract: The status of transient cooling of neutron star crusts is reviewed. Most observable heating episodes appear to come from magnetar outbursts. The results are quite consistent with magnetars having the crustal composition of normal neutron stars. Some heating events are accompanied by gamma rays but there also seem to be gamma-ray quiet heating episodes consistent with the picture of a complicated subsurface magnetic field.

Unal Ertan
Title: On the X-Ray and Infrared Enhancement of Anomalous X-ray Pulsar 1E 2259+58
Abstract: X-ray enhancement and the accompanying infrared enhancement light curves of the anomalous X-ray pulsar 1E 2259+58 can be accounted for by the relaxation of a fall back disk that has been pushed back by a gamma-ray flare. The required burst energy estimated from the results of our model fits is low enough for such a burst to have remained below the detection limits. We find that an irradiated disk model with a low irradiation efficiency is in good agreement with both X-ray and infrared data. Non-irradiated disk models also give a good fit to the X-ray light curve, but are not consistent with the infrared data for the first week of the enhancement.

Jacqueline K. Faherty
Title: The Trigonometric Parallax of Geminga. I. The Technique.
Abstract: We have obtained a series of four images of the nearby neutron star Geminga using the Advanced Camera for Surveys Wide Field Camera on the Hubble Space Telescope for the purpose of determining the parallax of Geminga. Because the magnitude of the expected parallactic shift is smaller than the camera's pixel size, great care must be taken at all stages of the reduction in order to obtain accurate astrometry. We fit each star in the images with an appropriate PSF and applied a distortion correction to generate stellar positions accurate to approximately 0.01 pixels (5 milli-arcsec). We then co-align the grids of 591 reference stars at each epoch. We examined all the stars in the reference grid, and carefully edited out those stars that failed to transform properly. We then measure the motions of Geminga with respect to this reference grid. In this paper we will concentrate on the techniques used. Our observations were obtained over 18 months, at the times of maximum parallactic shift. We will present a revised proper motion and parallax, accurate to 5 milli-arcsec.

Nelson L. Falcon
Title: Fast Cooling Stars and Heat Waves
Abstract: The thermal evolution of NS with internal heating admits the existence of Neutron superfluid layer and the possibility that may cool much faster than through ‘standard’ scenario. However in standard calculation of the cooling time the possibility of the heat propagation by waves is obviated. This simplification will be spurious in the degenerates material because, the relaxation time (the time required for to establish the heat flux when one temperature gradient is switched on) is not neglecting. Neutron Stars cooling theory is revised when the relaxation times are not negligible. The existence of the layer interior superfluid in NS facilitates the propagation of heat waves. Using the Cattaneo equation for the heat flux, it is shown changes in the energy transport equation and insinuates quasiperiodic pulses in the luminosity. Before the thermal relaxation, the Cooling Theory based in Cattaneo Law predicts that the energy is spread by heat waves and that the cooling time could be most short. Applications in rapid variations in single NS oscillators and quasi periodic luminosity pulses of non magnetic neutron stars are suggested.

Rodrigo Fernandez
Title: Modelling the Quiescent keV emission from Magnetars
Abstract: The observed quiescent keV emission from AXPs and SGRs is commonly fitted by a black body of kT~0.4 keV and a power law tail of photon index in the range [-4,-2]. This spectral shape is most likely the outcome of multiple resonant cyclotron scattering in a magnetosphere with a twisted magnetic field. Here we present Monte Carlo simulations of the X-ray emission that take into account the full three-dimensional structure of the magnetosphere. The resulting spectra and pulse profiles closely resemble those of the observed magnetars. The dependence of these results on the different parameters (magnetic field geometry, particle velocity distribution function, viewing angle) is explored.

Bryan Gaensler
Title: Are Magnetars Formed From Massive Progenitors?
Abstract: We review recent results on the environment of two magnetars: 1E 1048.1-5937 which is coincident with the expanding wind bubble of a massive star, and CXOU J164710.2-455216 which is associated with the young star cluster Westerlund 1. These and other recent results provide mounting evidence that magnetars originate from particularly massive stars. We discuss the resultant implications for the formation and birth-rate of magnetars, and for the magnetic field properties of their progenitor stars.

Bryan Gaensler
Title: Chandra Smells a RRAT: X-ray Detection of a New Class of Neutron Star
Abstract: The discovery of a new class of “Rotating RAdio Transients” (RRATs) has recently been reported by McLaughlin et al. (2005). These objects are characterized by occasional brief radio bursts, with average intervals between bursts ranging from minutes to hours. For 10 of the 11 RRATs, the burst spacings allow identification of periodicities, which fall in the range 0.4 to 7 seconds. The RRATs thus seem to be rotating neutron stars, albeit with properties very different from the rest of the population. We here present the serendipitous detection with the Chandra X-ray Observatory of a bright point-like X-ray source coincident with one of the RRATs. We discuss the temporal and spectral properties of this X-ray emission, consider counterparts in other wavebands, and interpret these results in the context of possible explanations for the RRAT population.

Joseph D. Gelfand
Title: Tracking the Remains of the Big One: The Evolving Radio Afterglow of the 27 Dec. 2004 Giant Flare from SGR 1806-20
Abstract: We present new results from our VLA/ATCA monitoring campaign on the radio nebula produced by the 27 Dec 2004 giant flare produced by SGR 1806-20. We will review the flux and spectral history over the first 500 days after outburst, and will also present new VLA A-array + Pie-Town observations which allow us to directly resolve the emission from the expanding ejecta. This new information on the light curve, size, shape and position of the radio source provides strong constraints on the process which created the nebula, and on the geometry and mechanism for the giant flare itself.

Janusz A. Gil
Title: Thermal X-ray emission from polar cap in drifting subpulse radio pulsars
Abstract: Within the framework of the inner acceleration region the relationship between the X-ray luminosity and the circulational periodicity of drifting subpulses is derived. This relationship is very well satisfied in pulsars for which an appriopriate radio and X-ray measurements exist. A special case of PSR B0943+10 is presented and discussed.

Kostas Glampedakis
Title: Elastic or magnetic? A toy-model of global magnetar oscillations and implications for QPOs during flares
Abstract: By means of a simple toy-model we estimate global MHD modes of a neutron star, taking into account the magnetic coupling between the elastic crust and the fluid core. Our results suggest that the modes most likely to be excited by a fractured crust, during a magnetar flare, are the ones that establish a resonance between the oscillating crust and core. The predicted frequencies are similar to the known crustal mode frequencies. Furthermore, our model offers a plausible explanation for the origin of the lower frequency (< 30 Hz) QPOs detected in the Dec 2004 giant flare of SGR 1806-20.

Matthew Ersing Gogus
Title: RXTE Observations of SGR 1806-20 Bursts
Abstract: SGR 1806-20 has been monitored with RXTE for about 2 years prior to the giant flare on 27 December 2004. In this talk, properties of SGR bursts detected within RXTE observations will be presented.

Marjorie E. Gonzalez
Title: Unusual X-ray emission from the young, high magnetic field radio pulsar PSR J1119-6127
Abstract: We report the first detection of pulsed X-ray emission from the radio pulsar PSR J1119-6127 using XMM-Newton. The pulsar has a characteristic age of 1,700 yrs and inferred surface dipole magnetic field strength of 4.1 × 10¹³ G. In the 0.5-2.0 keV range, the emission shows a single, narrow pulse with a very high pulsed fraction of ~ 70%. No pulsations are detected in the 2.0-10.0 keV range, where we derive an upper limit for the pulsed fraction of 28%. The pulsed emission is well described by a thermal blackbody model with a high temperature of ∼ 2.4 × 10⁶ K. Atmospheric models result in problematic estimates for the distance/emitting area. PSR J1119-6127 is now the radio pulsar with smallest characteristic age from which thermal X-ray emission has been detected. The observed combination of temporal and spectral characteristics provide an excellent test site for current models of thermal emission from neutron stars.

Eric Gotthelf
Title: Transient Anomalous X-ray Pulsar XTE J1810-197: Probing the Emission Mechanisms of Magnetars
Abstract: We present the latest results from a multi-epoch timing and spectral study of the Transient Anomalous X-ray Pulsar XTE J1810-197 obtained with the Newton X-ray Multi-mirror Mission (XMM). We have acquired seven observations over two and a half years to follow the spectral evolution as the source fades from outburst. The spectrum is arguably best characterized as a two-temperature blackbody whose respective luminosities are decrease exponentially with t1 = 870 d and t2 = 280 d. The temperatures of these components are starting to cool from the nearly constant values at earlier epochs of kT1 = 0.25 keV and kT2 = 0.67 keV, respectively. The pulsed fraction increases with energy, as expected for the smaller area of the hotter component. The extrapolated flux is projected to return to the historic quiescent level, characterized by an even cooler blackbody spectrum and smaller pulsed fraction, by the year 2007. We also present the detection of radio emission from XTE J1810-197, the first reported for any AXP, and consider possible scenarios for its origin.

Diego Gotz
Title: Unveiling SGR 1806-20 with INTEGRAL
Abstract:Thanks to its position close to the Galactic Centre, SGR 1806-20 has been one of the best monitored sources by INTEGRAL ever since the beginning of the mission. This has produced a wealth of new scientific results, which we willreview here. Since SGR 1806-20 was particularly active during the last two years, more than 300 short bursts have been observed with INTEGRAL and their characteristics have been studied with unprecedented sensitivity in the 15-200 keV range. A hardness-intensity anticorrelation within the bursts has been discovered and the overall Number-Intensity distribution of the bursts has been determined. In addition, a particularly active state, during which ~100 bursts were emitted in ~10 minutes, has been observed on October 5 2004, indicating that the source activity was increasing. This eventually led to the Giant Flare of December 27th 2004, discovered by INTEGRAL, for which a possible soft gamma-ray (>80 keV) early afterglow has been detected. The deep observations allowed us to discover the persistent emission of 1806-20 in hard X-rays (20-150 keV), which is so far unique among the SGRs.

Frank Haberl
Title: The pulsars among the Magnificent Seven
Abstract: Presently seven nearby radio-quiet isolated neutron stars with thermal X-ray emission are known which are sometimes called the “Magnificent Seven”. Five of them exhibit pulsations in their X-ray flux with periods in the range of 3.4 s to 11.4 s. XMM-Newton observations revealed broad absorption lines in the X-ray spectra which may be caused by cyclotron resonance absorption of protons or heavy ions. I'll review our present knowledge about this group of isolated neutron stars with particular emphasis on the pulse phase dependence of their X-ray spectra.

Pawel Haensel
Title: EOS of neutron-star cores and spin-down evolution of pulsars
Abstract: Hypothetical phase transitions in dense matter, such as pion or kaon condensation, or quark deconfinement, imply a softening of the EOS of neutron star cores. A softening of the EOS is also implied by hyperonization of matter. In each case, a softening of the EOS could result in a specific shape of the evolution track in the frequency - angular momentum plane. A sufficiently strong softening results in the back-bending phenomenon with a spin-up by the angular momentum loss epoch, followed in specific cases by a corequake. All this could have implications for the time evolution of pulsar frequency, which could hopefully yield precious information on the EOS at supranuclear densities.

Anahit R. Harutyunyan
Title: Observational manifestations of superdense stars containing quark matter
Abstract: Possible implications for quark phase transition inside superdense stars are studied, based on the series of calculated models. The stars considered were pure quark stars ( or strange stars ) and hybrid stars consisting of a quark matter core with a nuclear matter crust around. The observational consequences are affected very much by the features of the process of star restructuring, when phase transition occurs in the interior of a star. The detailed analysis of the parameters of calculated configurations, useful for comparison with neutron star observables, is carried out. Such comparison might help to test the used equations of state for superdense matter. Possible observational tests are discussed to distinguish between the ordinary neutron stars, strange stars and superdense hybrid stars.

Brynmor D. L. Haskell
Title: Mountain on Neutron stars
Abstract: I will discuss the maximum size of a “mountain” that the crust of a Neutron star could sustain. In particular I will focus on the difference between an accreted and a non-accreted crust, and try to give an estimate of how important relativistic effects may be.

Ian Hawke
Title: Gravitational wave emission from collapsing neutron stars
Abstract: Gravitational wave observation may give crucial information about matter at neutron star densities, particularly from violent events such as the collapse to a black hole. Computing waveforms requires numerical simulations of the Einstein-Euler equations without symmetries, an extremely difficult task. Techniques used for such simulations will be presented along with methods of analyzing the resulting spacetime (through, for example, studying the black hole horizons), as well as direct computations of gravitational waveforms from neutron star collapse.

Jillian A. Henderson
Title: Is RX J1856.5-3754 a Strange Star ?
Abstract: RX J1856.5-3754 has been proposed as a Strange Star candidate due to its very small apparent radius measured form its X-ray thermal emission. However, its optical emission requires a much larger radius and thus most of the stellar surface must be cold and undetectable in X-rays. In the case the star is a neutron star such a surface temperature distribution can be explained by the presence of a strong toroidal field in the crust (Perez-Azorin et al 2005, Page et al. 2005). We consider a similar scenario for a Strange Star with a thin baryonic crust to determine if such a magnetic field induced effect is still possible or excludes RX J1856.5-3754 as a Strange Star.

Wim Hermsen
Title: Vela pulsar profiles from the radio to high-energy gamma-rays
Abstract: The Vela pulse profiles from the radio domain up to the high-energy gamma-rays exhibit more fine structure than found so far for any other radio pulsar. Broad pulses and sharp feautures down to widths of ∼1 ms are visible, the latter e.g. in the optical, UV and X-rays. The spectra of the pulse components are vastly different. We will compare profiles in the radio, optical and UV with those found in the X-ray till gamma-ray domain, using XMM-Newton, Chandra, RXTE, INTEGRAL, OSSE, COMPTEL and EGRET data. There is evidence for at least seven distinct components in the X-ray profiles, including a new peculiar soft X-ray pulse only visible between 200 and 800 eV with a duty cycle of ∼10%. The latter seems to be too narrow for a thermal component from the surface of the neutron star. Interestingly, one of the very narrow pulses appears to coincide in phase with that of the reported giant micro pulses detected from Vela in the radio, similar to the phase alignment of giant radio pulses and non-thermal X-rays reported for millisecond pulsars PSR J1937+21 and PSR B1821-24 and the Crab. The observational evidence will be presented and implications discussed.

Jeremy S. Heyl
Title: QED can explain the non-thermal emission from SGRs and AXPs
Abstract: Owing to effects arising from quantum electrodynamics (QED), magnetohydrodynamic fast modes of sufficient strength will break down to form electron-positron pairs while traversing the magnetospheres of strongly magnetised neutron stars. The bulk of the energy of the fast mode fuels the development of an electron-positron fireball. However, a small, but potentially observable, fraction of the energy (∼ 10³³ ergs) can generate a non-thermal distribution of electrons and positrons far from the star. In this paper, we examine the cooling and radiative output of these particles. Small-scale wave may produce only the non-thermal emission. The properties of this non-thermal emission in the absence of a fireball match those of the quiescent, non-thermal radiation recently observed non-thermal emission from several anomalous X-ray pulsars and soft-gamma repeaters.

Wynn Ho
Title: Magnetic Hydrogen Atmosphere Models and the Neutron Star RX J1856.5-3754
Abstract: RX J1856.5-3754 is one of the brightest, nearby isolated neutron stars. Considerable resources have been devoted to its observation in an attempt to constrain realistic atmosphere models and measure spectral lines. While the multiwavelength spectrum is well-fit by a simple two-temperature blackbody model without any spectral features, this model can require an unphysically large radius (R^∞ > 20 km) and generally implies pulsations that have yet to be detected. Light element atmosphere models greatly overpredict the optical/UV flux, while heavy element atmosphere models predict a large number of unobserved spectral features in the X-ray regime. We show that our latest magnetic, partially ionized hydrogen atmosphere models can fit the entire spectrum, from X-rays to optical, of RX J1856.5-3754. The model fit requires only a single temperature. Our model is the most self-consistent picture for explaining all the observations of RX J1856.5-3754.

Jorge E. Horvath
Title: What do exotic models of compact stars have to offer?
Abstract: We present an short general overview of the main features of exotic models of neutron stars, focusing on the structural and dynamical predictions of the former. In particular, we discuss the presence of “normal” quark matter and CFL states, including their possible self-bound versions, as well as some different proposals emerging from the study of QCD microphysics. A connection with actual observed data is the main goal to be addressed at this talk and along the meeting.

Jorge E. Horvath
Title: SGR 1806-20 as a source of gravitational waves: constraints on models after the Dec 27, 2004 superflare
Abstract: We discuss the generation of gravitational waves by the Soft-Gamma Repeater 1806-20, the latest to show a large superflare dwarfing the previously known events from other sources. We show which constraints are obtained for a few models of energy release and compare with the existing limits obtained by operating GW experiments, mainly the released data from the AURIGA at ∼ 1 kHz.

Alaa I Ibrahim
Title: Discovery of a 20 keV Absorption Feature from SGR 1806-20: Evidence of Vacuum Resonance in a Magnetar Atmosphere?
Abstract: We present the detection of a 20 keV absorption line in the burst spectra of the soft gamma repeater SGR 1806-20. The feature is not well explained in terms of conventional scenarios such as cyclotron resonance or atomic lines. A hitherto unobserved vacuum resonance mechanism due to the interplay between the magnetar field and the atmospheric plasma may provide a plausible interpretation that confirms earlier theoretical predictions. If this identification is indeed correct, the feature offers a unique opportunity to observe manifestations of QED and estimate the density of matter in the neutron star environment.

Alaa I Ibrahim (A. Ibrahim, H. Anwar, M. Soliman, K. Dhuga, N. Mackie-Jones)
Title:The Origin of the 6.4 keV Emission Line from SGR 1900+14
Abstract: A 6.4 keV emission line from SGR 1900+14 was the first line spectrum to be observed in the burst spectra of Soft Gamma Repeaters. Since its discovery in 2000, the origin of this line remained uncertainly known. Here we present the results of RXTE observations that give a new insight on the identification of this mysterious line.

Nazar Ikhsanov
Title: Accretion by isolated neutron stars
Abstract: An identification of old isolated neutron stars accreting material from interstellar medium remains an open problem. A lack of success in searching for these objects by recent X-ray missions indicates that the rate of mass accretion onto the surface of these stars is significantly smaller than the average mass capture rate by a neutron star from its interstellar environment. I show that this situation is realized for neutron stars in the state of subsonic propeller, which has been incorporated into the evolutionary tracks of the neutron stars first by Davies, Fabian and Pringle. The mass accretion rate onto the stellar surface in this case is limited to the rate of plasma diffusion into the magnetic field of the star at the magnetospheric boundary, which is a few orders of magnitude smaller than the maximum possible rate of mass capture by the star from its environment. The duration of this stage under the conditions of interest exceeds 1Gyr making the probability to detect an old isolated neutron star with current X-ray missions negligibly small. Some alternative possibilities to solve the above mentioned problem will be briefly reviewed.

Gianluca Israel
Title: 2004: de SGR1806-20 anno mirabile
Abstract: During 2004 we followed in the IR band the increased hard X-ray burst activity of SGR1806-20 thanks to an ESO ToO program which allowed us to discover the likely IR counterpart and to draw a first broad band energy spectrum encompassing energies from IR up to hundreds keV. This discovery make also possible a first comparison of the SGR 1806-20 properties with those of AXPs and a sample of radio pulsars. The IR monitoring is still on going and the most recent results will be shown. Moreover, on 27^th December 2004 SGR1806-20 displayed an extremly rare event, named giant flare, during which more than 10⁴⁷ ergs were released. Thanks to serendipitous data collected by the RossiXTE satellite we performed the first detailed timing analysis of such an event discovering QPOs at 18, 30 and 92.5Hz, the first ever for a magnetar candidate. We interpreted these fast signals in term of toroidal global seismic oscillations on the neutron star surface likely due to fractures. The implications of the QPO discovery will be reviewed.

Ian Jones
Title: Isolated neutron stars and gravitational waves
Abstract: In this talk I will discuss isolated neutron stars as gravitational wave sources. I will pay particular attention to the challenges of searching for gravitational waves from stars where electromagnetic observations have yet to reveal any pulsations. I will describe the difficulties unique to such stars, and also discuss some interesting population issues that impact on gravitational wave search strategies.

Alexander Kaminker
Title: Cooling of Isolated Neutron Stars With Magnetized Envelopes
Abstract: We discuss new scenarios of neutron star cooling (the so called minimal cooling scenarios) in which Cooper-pairing neutrino emission in superfluid nucleon stellar cores initiates an enhanced cooling even if the powerful direct Urca process (or any other enhanced neutrino process in non-superfluid matter) is forbidden. The initial versions of these scenarios were proposed by Page et al. (2004) and Gusakov et al. (2004). In particular, we can explain observations of isolated neutron stars coldest for their age (PSR J0205+6449, the Vela pulsar, and RX J0007.0+7302), by the Cooper-pairing neutrino emission in nucleon cores. Special attention is paid to the effects of surface layers of light (accreted) elements and of a strong magnetic field on cooling of low-mass neutron stars. These effects enable us to explain observations of isolated neutron stars hottest for their age, e.g., RX J0822-4300 or PSR B1055-52. To explain observations of thermal radiation from magnetars we need to include additional reheating mechanisms in crusts and/or cores of relatively young neutron stars (of age > 10⁵ years). We show that the reheating mechanisms in the magnetar cores are relatively inefficient because of strong neutrino cooling of these cores. We discuss possible reheating mechanisms in magnetar crusts.

David Kaplan
Title: X-ray Timing of Two Nearby, Isolated Neutron Stars
Abstract: We will report on our recent X-ray timing program of two nearby, isolated neutron stars: the 8.39-s RX J0720.4-3125 and the 5.16-s RX J1308.6+2127. By combining new, dedicated Chandra observations with archival Chandra, XMM-Newton, and ROSAT observations, we have been able to determine phase-coherent timing solutions for both sources stretching back at least 5 years. These solutions imply similar magnetic fields (2.4×10¹³ G and 3.4×10¹³ G) and spin-down ages (1.9 Myr and 1.5 Myr). We will discuss these solutions in the context of the population of similar objects and as they influence our understanding of the broad X-ray absorption features in their X-ray spectra.

Oleg Kargaltsev
Title: Thermal Radiation from Pulsars, from X-rays to Ultraviolet
Abstract: As we know from Chandra and XMM-Newton observations, many pulsars exhibit thermal component(s) in their X-ray spectra. To better understand the origin of the thermal emission, we observed several pulsars at the far-UV and near-UV wavelengths with the STIS/MAMA detector aboard Hubble Space Telescope and measured their UV spectra and pulse profiles. We found that the UV spectra of three pulsars, B0656+14 (τ ≈ 0.1 Myr), Geminga (τ ≈ 0.3 Myr) and J0437-4715 (τ ≈ 5 Gyrs) show Rayleigh-Jeans tails of thermal emission from the neutron star surface. We will present an overview of observational results on thermal X-rays from pulsars, describe the properties of the observed UV emission, examine its connection with the X-ray and optical spectra, compare the UV/X-ray properties of radio pulsars and radio-quiet isolated neutron stars, and discuss implications for the neutron star cooling/heating models and emission mechanisms.

Sergey Karpov (S. Karpov, G.M. Beskin, A. Shearer, M. Redfern, O. Ryan, G. Hallinnan)
Title: Short time scale pulse stability of the Crab pulsar in the optical band.
Abstract: The stability of the optical pulse of the Crab pulsar is analysed based on the 1 us resolution observations with the 6-meter telescope equipped with the APD avalanche photo-counter. The search for the variations of the pulse shape along with its arrival time stability is performed. Upper limits on the possible short time scale free precession of the pulsar and the stochastic variable optical emission component are placed.

Victoria Kaspi
Title: Anomalous X-ray Pulsars
Abstract: Anomalous X-ray Pulsars (AXPs) share many observational properties with Soft Gamma Repeaters, and both are now thought to be magnetars. However there remain many open questions in this picture, including several observed AXP phenomena that are perhaps surprising in current versions of the magnetar model. Most notable is the surprising variety of AXP variability behavior, in magnitude, type, and time scale. In this presentation I will first review the well understood properties of AXPs, and then focus on some of puzzles that recent observations of AXP variability have revealed.

Victoria Komarova
Title: Optical search for counterparts to isolated neutron stars at the 6m telescope of SAO RAS
Abstract: Some results of the program for search for and studies of optical counterparts to pulsars and candidates to isolated neutron stars, such as RX J0007+7302, AXP 4U0142+61, PSR B0823+26, PSR B1951+32, RBS 1774, PSR B2334+61 and others, at the 6m telescope SAO RAS are presented. Broadband observations of the target fields along with studies in H-alpha line of some of them have been carried out with the prime focus photometer and the focal reducer SCORPIO in the image mode. Upper limits on the level of detection and flux estimates of the objects under investigation have been obtained.

Arkadi Kuzmin
Title:Giant Pulses of Pulsar Radio Emission
Abstract: Review report of giant pulses of a pulsar radio emission, based on the survey of the main poperties of all known pulsars with giant pulses, including our detection of 3 new pulsars with giant pulses.

Lucien Kuiper
Title: Hard X-ray (10-100 keV) timing and spectral properties of young spin-down powered pulsars
Abstract: During the past 6 years several young and energetic spin-down powered pulsars have been detected at X-rays (2-10 keV) in or near prominent supernova remnants. These pulsars are all radio dim (or even quiet) with fluxes near 100 Jansky, explaining the initial non-detections during radio-surveys. We analysed archival X-ray data from RXTE PCA/HEXTE (2-250 keV) to derive the timing and spectral characteristics for a sample of four of these pulsars at hard X-rays. We derived an accurate timing model for PSR J1846-0258, the pulsar in Kes 75, based on X-ray timing observations spanning a ∼9 years time interval. The measured breaking index of 1.20(3) is the lowest measured so far for any spin-down powered pulsar and puts severe constraints on the pulsar properties at its birth. Its high-energy pulsed spectrum is hard with a photon index of 1.07(1) and its pulsed emission has been detected up to 80 keV in RXTE HEXTE data, making it the fifth pulsar detected at such high X-ray energies. This is confirmed in a timing analysis of INTEGRAL IBIS ISGRI (20-300 keV) data. Moreover, for the first time we detected significant pulsed emission above 20 keV from PSR J1930+1852 (in G54.1+0.3), PSR J1811-1925 (in G11.2-0.3) and PSR J1617-5055 (near RCW 103). The pulsed spectra of these young pulsars are also very hard with photon-indices in the range 1.0 - 1.3. Finally, the results from a recent 33 ks Chandra observation of the very young pulsar PSR J1357-6429, possibly associated with G309.8-2.6, will be presented.

Dong Lai
Title: Neutron Star Surfaces and and their Radiation
Abstract: The last few years have seen significant observational progress in the study of surface radiation from magnetic neutron stars, including radio pulsars, dim isolated neutron stars and magnetars. Modeling such radiation requires a detailed understanding of the property of matter in strong magnetic fields and radiative processes in highly magnetized, birefringent plasmas. I will discuss recent works and challenges on theoretical modeling of neutron star surfaces and atmospheres. I will focus on issues related to radiative transfer in strong magnetic fields, recent calculation of magnetic condensed matter and implication for high-B pulsars and magnetars.

Jim Lattimer
Title: Equation of State Constraints from Neutron Stars
Abstract: Recent measurements of thermal radiation from neutron stars have suggested a rather broad range of radiation radii [R_inf=R/√(1-2GM/Rc²)]. Sources in M13 and Omega Cen imply R_inf ∼ 12-14 km, but X7 in 47 Tuc implies R_inf ∼ 16-20 km and RX J1856-3754 R_inf > 17 km. If these measurements are all correct, only a limited selection of EOS’s could be consistent with them, but a broad range of neutron star masses (up to 2 M_sun) would also be necessary. The surviving equations of state are incompatible with significant softening above nuclear saturation densities, such as would occur with Boson condensates, a low-density quark-hadron transition, or hyperons. Other potential constraints, such as from QPOs, radio pulsar mass and moment of inertia measurements, and neutron star cooling, will be compared.

Kseniya Petrovna Levenfish
Title: Dichotomy of thermal states of SXRTs vs neutron superfluidity in neutron stars cores
Abstract: We show that data on thermal emission from SXRTs in quiescence indicate the absence of mild neutron superfluidity in neutron stars cores (both in the outer and inner ones). Were such superfluidity available, nearly the same transients would evolve to quite different thermal steady-states with the “barred” states in-between. Probable absence of the mild neutron superfluidity constrains available scenarios of enhanced cooling of neutron stars.

Xiangdong Li
Title: Spin down of young neutron stars with a fallback disk
Abstract: Disks originating from supernova fallback have been suggested to surround young neutron stars. Interaction between the disk and the magnetic field of the neutron star may considerably influence the evolution of the star through the so called propeller effect. There are many controversies about the efficiency of the propeller mechanism proposed in the literature. We investigate the fallback diskinvolved spin-down of young pulsars. By comparing the simulated and measured results of pulsar evolution, we present some possible constraints on the propeller torques exerted by the disks on neutron stars.

Bennett Link
Title: Precession as a Probe of the Neutron Star Interior
Abstract: The mounting evidence that some neutron stars precess (nutate) with long periods (∼1 yr) presents new challenges to our current understanding of the neutron star interior. I will describe how neutron star precession can be used to constrain the state of the interior in a new way. I will argue that the standard picture of the outer core, in which superfluid neutrons coexist with type II, superconducting protons, is incorrect. One possible resolution is that the protons are not type II, but type I. Another possibility is that the neutrons are normal in the outer core. I will briefly discuss the implications for neutron star cooling.

Margaret A. Livingstone
Title: New measurements of pulsar braking indices
Abstract: The measurement of pulsar braking indices (n) provides important insight into the physics governing the rotational evolution of pulsars. We present a review of all braking index measurements and discuss possible physical explanations for the discrepancy between the theoretical value of n=3 and observations. In addition, we present the first ever measurement of n for the young, energetic, and high magnetic field puslar PSR J1846-0258 located at the center of the supernova remnant Kes 75. Our measured value (n=2.65±0.01) is significantly less than that expected from magnetic dipole radiation (n=3), as is the case for all 5 other measured braking indices. This value provides an improved age estimate of ∼880 yr — the youngest age estimate for any rotation-powered pulsar.

David Lomiashvili
Title: Non-precession Model of Rotating Radio Transients
Abstract: During the last few years there were discovered and hardly examined several transient neutron stars (“Rotating Radio Transients”). It's already well accepted that these objects are radio pulsars. But their extraordinary features (burst-like behavior) made necessary revision of well accepted models of pulsar interior structure. Nowadays most popular model for RRATs is precessing pulsar model, which is subject of big discussion. We present a non-precession model of these objects which is not at variance with old theories. An important feature of our model which provides natural explanation of most of the properties of these neutron stars, is presence of very low frequency nearly transverse drift waves propagating across the magnetic field and encircling the open field lines region of the pulsar magnetosphere.

German Lugones (G. Lugones, J. E. Horvath and E. M. de Gouveia Dal Pino)
Title: Giant flares of SGRs: Evidence for the birth of quark stars
Abstract: We propose that giant flares of SGRs can be interpreted as the conversion into quark matter of an isolated neutron star with a subcritical magnetic field ∼ 10¹² G. We show that, in a timescale of ∼ 10⁵ yrs, accretion from a fallback disk can increase the mass of the central object up to the critical mass for the conversion into a quark star. Also, several characteristics of the giant flare of SGR 1806-20 on 27 December 2004 (such as spike and tail energies and timescales) can be explained as the result of the cooling and deleptonization of the central compact object after the conversion.

German Lugones
Title:Nucleation of superconducting quark bubbles and implications for neutron star structure
Abstract: In order to convert a neutron star into a strange quark star or a hybrid star, it is necessary first to nucleate a small drop of quark matter at the centre. This drop could eventually grow and convert part or the whole star. We investigate the quantum nucleation of color superconducting bubbles, and find the threshold value of the central pressure (or gravitational neutron star mass) above which a neutron star is metastable to the conversion to a hybrid neutron star or to a strange star. We explore the consequences for neutron star structure (normal + “exotic” populations) and estimate the energy released in the conversion.

Andrew G. Lyne
Title: The Pulsar-Magnetar Connection
Abstract: A number of recently discovered radio have rotational properties which are similar those of the magnetars, making the separation of the two populations much less distinct. I will present recent observations that address the possibility that the two populations have an evolutionary link.

Valery Malofeev
Title: Radio emission from AXP and XDIN
Abstract: The result of the search and the investigations of radio emission from two groups of isolated neutron stars (AXP and XDIN) are reported. The observations were carried out on two high-sensetivity transit radio telescopes in Pushchino at the frequencies 111, 87, 61 and 42 MHz. The flux densities or their upper limits, mean pulse profiles and the dispersion measures are presented, as well as the estimation of spectral indices, distances and integrated radio luminosities. The comparison of radio and X-ray data have been made for two-three objects.

Igor Fedorovich Malov
Title:The drift model of 'magnetars'
Abstract: Drift waves in outer layers of neutron star magnetospheres can explain the basic peculiarities of AXPs, SGRs, and radio pulsars with very long periods. It is shown that neutron stars with rotation periods of order 0.1 s and angles between rotation and magnetic axes less than 10 degrees can exhibit themselves as AXPs and SGRs. Their X-ray and gamma-ray emissions can be connected with relativistic electrons and positrons in the magnetosphere. Magnetic fields at surfaces of objects under consideration are of order 10¹¹ - 10¹³ G, usual for normal radio pulsars.

Armando Manzali
Title: An XMM-Newton assessment of the spectral shape of the Vela pulsar
Abstract: We report on our analysis of two XMM-Newton observations of the Vela Pulsar performed in December 2000 (total exposure time: 96.5 ks). We succeeded in resolving the pulsar spectrum from the surrounding bright nebular emission taking advantage both of the accurate calibration of the EPIC point spread function and of the Chandra/HRC surface brightness map of the nebula. This made it possible to assess to pulsar spectral shape disentangling its thermal and non thermal components. Exploiting the photon harvest, we have also been able to perform a phase-resolved study of the pulsar emission.

Katie McGowan
Title: X-ray Observations of PSR B0355+54 and Its Pulsar Wind Nebula
Abstract: We will report on XMM-Newton and Chandra observations of the middle-aged 156 ms radio pulsar PSR B0355+54. Our analysis shows not only emission from the pulsar itself, but also diffuse emission extending ∼50 arcsec in the opposite direction to the pulsar's proper motion. We will present the results of the spectral and timing analysis of the core pulsar emission and the diffuse component, and discuss the origin of the latter.

Sandro Mereghetti
Title: The XMM-Newton view of Soft Gamma-ray Repeaters
Abstract: All the confirmed Soft Gamma-ray Repeaters have now been observed with the EPIC instrument on XMM-Newton, which has provided the spectra with the highest statistics on the persistent X-ray emission from these objects. This allowed us to obtain high quality pulse profiles and phase-resolved spectra. No evidence for spectral lines has been found. Several observations are available for SGR 1806-20, which displayed exceptional activity in the last few years and has been caught in different spectral and intensity states. A comparison with SGR 1900+14 and SGR 1627-41, that are currently in a non-bursting state, as well as with the AXPs observed with XMM-Newton, allows to study the relation between the persistent emission of SGRs and the level of source activity.

Roberto P. Mignani
Title: Studies of Neutron Stars at Optical/IR Wavelengths
Abstract: Recent results on the studies of Isolated Neutron Stars in the optical/IR are reported, following observations with both HST and VLT. The observed objects are “canonical” radio pulsars, young high-magnetic field pulsars and old X-ray Dim Neutron Stars for which proper motion measures, polarimetric and imaging observations have been collected.

Kaya Mori
Title: Magnetized Oxygen atmosphere models and their application to the isolated neutron star 1E1207.4-5209
Abstract: We present LTE Oxygen atmosphere models at B ∼ 10¹² G. The models are constructed specifically for the isolated neutron star 1E1207.4-5209 which shows two broad absorption features in the X-ray band. We constructed opacity tables and equation of state by addressing all the physics relevant to strongly-magnetized dense plasmas. Radiative transfer equations are solved to determine self-consistent temperature profiles and emergent spectra. Our model spectra will be directly compared with the 260 ksec XMM-Newton data of 1E1207.4-5209. We will also discuss several important implications of Oxygen atmosphere.

Christian Motch
Title: Measuring proper motions of isolated neutron stars with Chandra
Abstract: We are currently conducting with Chandra a proper motion study of two X-ray bright and radio quiet isolated neutron stars lacking an optical counterpart. Using specific analysis methods, it is possible to take advantage of the beautiful spatial resolution of Chandra to accurately measure small displacements. We present our first results and show how they can be used to constrain the origin, distance and evolutionary status of these objects.

Elena Nokhrina
Title: On the surface current in a neutron star polar cap
Abstract: The surface current structure in a polar cap of a neutron star may pose some restrictions on both the magnetosphere structure of a pulsar and its evolution and energy losses. The detailed analysis of the surface current shows that the energy losses for an orthogonal rotator are much smaller than for an aligned one. Also, it seems that the structure of a magnetosphere itself may depend crucially on the boundary conditions at the star surface, in particular, on the magnitude of a current that can be provided by the inner gap.

Elena Nokhrina
Title: Acceleration of plasma outflows from compact astrophysical sources
Abstract: The problem of the efficiency of particle acceleration for paraboloidal poloidal magnetic field is considered within the approach of steady axisymmetric MHD flow. For the large Michel magnetization parameter σ it is possible to linearize the stream equation nearthe force-free solution and to solve the problem self-consistently. It is shown that on the fast magnetosonic surface the particle Lorentz factor γ does not exceed the standard value σ^1/3. On the other hand, in the supersonic region the Lorentz factor grows with the distance z from the equatorial plane as γ ≈ (z/R_L)^1/2 up to the distance z ≈σ² R_L, where R_L=c/Ω_F is the radius of the light cylinder. Thus, the maximal Lorentz factor is γ_max ≈σ, which corresponds to almost the full conversion of the Poynting energy flux into the particle kinetic one.

Hakki B Ogelman
Title: X-ray observations of pulsars during Chandra-Newton era
Abstract: With its soft X-ray response ROSAT has revealed a soft X-ray picture of neutron stars; now with the sensitive new satellites CHANDRA and NEWTON we are emphasizing the hard X-ray emission revealing magnetospheric and nebular emission from pulsars. These new results will be summarized and discussed

Dany P. Page
Title: Thermal Evolution of Neutron Stars with Strong Magnetic Fields
Abstract: I will describe how strong magnetic fields can modify the cooling of isolated neutron stars, with particular emphasis on the effects of the presence of strong toroidal components. These field structures, beside possibly contributing as heating source, also have very efficient blanketing effects and strongly modify the late evolution during the photon cooling stage. Comparison with the XDINs and AXPs will be presented.

Qiu-he Peng
Title: The Origin of the superstrong magnetic field of neutron stars and magnetars
Abstract: We estimate the strength of the induced magnetic field due to the total magnetic moment of the anisotropic (3PF2) neutron superfluid interior of neutron stars. The induced magnetic field of the neutron stars will increase gradually in their late evolutionary stage. A magnetar will appear if the mass of the 3PF2 neutron superfluid is more than 10^-2 solar mass.

Adriana Pires
Title: TBA
Abstract: TBA

Jose Pons
Title: The anisotropic thermal emission of magnetized neutron stars
Abstract: The thermal emission from isolated neutron stars is not yet well understood. The X-ray spectrum is very close to a blackbody but there is a systematic optical excess flux with respect to the extrapolation to low energy of the best blackbody fit. This fact, in combination with the observed periodicity in the X-ray flux, can be explained by anisotropies in the surface temperature distribution.We study the thermal emission from neutron stars with strong magnetic fields in order to explain the origin of the anisotropy, by constructing stationary solutions in axial symmetry of the radiative transfer equations in the neutron star crust and the condensed envelope. The presence of magnetic fields of the expected strength leads to anisotropy in the surface temperature. Models with toroidal components similar or larger to the poloidal field reproduce qualitatively the observed spectral properties and variability of isolated neutron stars. Our models also predict spectral features at energies between 0.2 and 0.6 keV.

Sergey B. Popov
Title: Neutron star masses: dwarfs, giants and neighbours
Abstract: In my talk I discuss the variety of neutron star masses. At first the possibility of the formation of low-massive (∼ 0.5 M_sun) compact objects due to fragmentation of a rapidly rotating protoneutron star is discussed (astro-ph/0403710). Then I discuss the opposite case of very massive neutron stars which gain their masses due to accretion in binaries (A&A 434, 649 (2005)). Mass distribution for such objects is presented. Finally, I concentrate on the mass spectrum of near-by compact objects. It is shown that the mass spectrum used in our population models (astro-ph/0411618) with the abrupt cutoff at ∼ 1.4 - 1.5 M_sun has significant observational support in masses determined for secondary companions of double neutron star binaries. The important consequence, summarized in the mass constraint, is that close-by cooling neutron stars have to be explained with cooling curves which correspond to masses M ≤ 1.5 M_sun. This constraint has to be taken into account in discussing different models of the thermal evolution of neutron stars.

Bettina Posselt
Title: XDINSs as soft X-ray sources
Abstract: The Magnificient Seven have all been discovered by their exceptional soft X-ray spectra. However, they are all probably nearby sources. Dealing with larger distances and thus larger interstellar absorption may result in harder X-ray counterparts. We will discuss this effect and the importance of considering hardness ratios to find new XDINSs. Furthermore we will present our results on the search for new XDINS candidates using ROSAT PSPC / HRI and XMM pointings in combination with the relatively deep optical Sloan Digital Sky Survey.

Alexander Y Potekhin
Title: The effects of strong magnetic fields on neutron-star thermal radiation
Abstract: Strong (B » 10⁹ G) and superstrong (B ≥ 10¹⁴ G) magnetic fields profoundly affect many thermodynamic and kinetic characteristics of matter in neutron star envelopes. In particular they affect thermal conductivity tensor in the crust and the equation of state and radiative opacities in the atmosphere, which are major ingredients of the cooling theory and spectral atmosphere models. As a result, both the thermal luminosity and the spectrum of a neutron star can be modified by the magnetic field. I review these effects, putting emphasis on the considerable progress in their understanding, achieved in recent years, and on some qualitative differences brought about by the superstrong fields. Using modern theoretical models, I demonstrate the influence of the strength and configuration of the magnetic field on the thermal emission of an isolated neutron star, and show under which conditions this influence should be important for interpretation of observations of such emission.

Nanda Rea
Title: Our distorted view of the magnetars
Abstract: Recent theoretical works showed the possibility that our X-ray spectral view of magnetars might be distorted by a resonant cyclotron scattering of the surface radiation in the magnetospheres of these highly magnetic neutron stars. I will report on the observational evidence of this effect in the Chandra and XMM-Newton magnetars’ spectra.

Nanda Rea
Title: Foresee magnetars' variability
Abstract: The long term X-ray monitoring of the AXP 1RXS J1708-4009, revealed a clear intensity-hardness correlation in its emission. More interestingly, the source was caught with the highest flux (hardest spectrum) in coincidence with its glitching activity, and possibly with bursts. A recent Swift observation of this source confirms the intensity-hardness correlation and revealed an increase of the source flux. Through a detailed modelling of this correlation, we try to predict the epoch of the next glitching, and maybe bursting, activity of this source.

Sanjay K Reddy
Title: Strange Stars: A Crust with Nuggets
Abstract: If strange quark matter is the true ground state of matter then a new class of compact objects called strange stars are a possibility. Contrary to earlier studies we will show that such stars could have a solid crust. The heterogenous crust consists of strange nuggets embedded in a degenerate electron background. Deeper within it is likely that the crust is characterized by voids of hadronic vacuum embedded in quark matter background. We discuss how such a crust would affect observable aspects of compact stars.

Andreas Reisenegger
Title: Internal heating and thermal emission from old neutron stars: constraints on dense-matter and gravitational physics
Abstract: The equilibrium composition of neutron star matter is achieved through weak interactions (direct and inverse beta decays), which proceed on relatively long time scales. If the density of a matter element is perturbed, it will relax to the new chemical equilibrium through non-equilibrium reactions, which produce entropy that is partly released through neutrino emission, while a similar fraction heats the matter and is eventually radiated as thermal photons (Reisenegger 1995). We examined two possible causes of such density perturbations: 1) the reduction in centrifugal force caused by spin-down (particularly in millisecond pulsars), leading to rotochemical heating T (Fernadez & Reisenegger 2005, ApJ), and 2) a hypothetical time-variation of the gravitational constant, as predicted by some theories of gravity and current cosmological models (gravitochemical heating T; Jofr 2005, undergraduate thesis). If only slow weak interactions are allowed in the neutron star (modified Urca reactions, with or without Cooper pairing), ‘rotochemical heating’ can account for the observed ultraviolet emission from the closest millisecond pulsar, PSR J0437-4715 (Kargaltsev et al. 2004, ApJ), which also provides a constraint on |dG/dt| of the same order as the best available in the literature.

Malvin Ruderman
Title: Thermal emission areas of heated neutron star polar caps
Abstract: Pulsar polar caps are heated by the backflow of very energetic electrons or positrons from accelerators on the open magnetic field line bundle between the neutron star’s surface and its light cylinder. The surface area of the polar caps is proportional to the star’s spin-rate and also to the ratio of its surface dipole field to the local field at the polar cap. By a thousand (or less) years after the neutron star’s birth, its core is expected to have cooled sufficiently for the formation of a twisted array of quantized proton-superconductor flux tubes threaded by a nearly uniform lattice of neutron-superfluid vortex lines. Thereafter, interaction between the two couple the star's spin with its magnetic dipole moment and its polar cap surface field. A variety of evidence will be presented for this with emphasis on understanding why polar cap areas are expected (and observed) to be so small on spun-up millisecond pulsars and also on very many spinning-down neutron stars. Cyclotron resonant scattering by electron-positron flows of the thermal x-ray emission from a polar cap (or of cooling emission from the entire stellar surface) during passage through the inner magnetosphere may also cause surface areas inferred from observations to be very much smaller than actual ones.

Motoyuki Saijo
Title: Viscosity driven instability in rotating relativistic stars
Abstract: We investigate the criterion of viscosity driven instability in rotating relativistic star by means of an iterative evolution approach of an equilibrium star (Bonazzola, Frieben, Gourgoulhon 1996; 1998). We focus on a polytropic rotating equilibrium star and put an m=2 perturbation in the lapse function, which corresponds to gravitational potential in the Newtonian limit. We vary both the stiffness of the equation of state and the compaction of the star whether these two parameters do significantly depend on the critical value. For a rigidly rotating star, the criterion T/W, where T is the rotational kinetic energy and W is the gravitational binding energy, mainly depends on the compaction of the star and takes its value around 0.13 ∼ 0.16, which varies from that of Newtonian incompressible stars (∼ 0.14). For a differentially rotating star, the critical value takes around 0.18 ∼ 0.25, which is significantly larger than the rigidly rotating case with the same compaction of the star. Finally we discuss a condition when our finding takes place in an astrophysical scenario, such as accreting neutron stars.

Lars Samuelsson
Title: Oscillations in the Neutron Star Crust
Abstract: It has been suggested that the quasi periodic oscillations detected in aftermath of giant flares are associated with torsional oscillations of the neutron star crust. In this talk I will present a simple model for such oscillations in general relativity and discuss the difficulties that have to be overcome in order to extract useful information about, for example, the equation of state of dense matter.

Axel Schwope (A. Schwope (AIP), V. Hambaryan (AIP), F. Haberl (MPE))
Title: A second absorption feature in the X-ray spectrum of RBS1223
Abstract: We present preliminary results of a deep X-ray spectrum of the X-ray dim isolated neutron star RBS1223. The data set consists of 4 new XMM-Newton EPIC pn monitoring observations combined with already published data obtained between 2003 and 2006. The net exposure time is 113 ksec, the mean spectrum contains about 290000 EPIC pn X-ray photons. Spectral analysis of the spin-phase averaged spectrum shows, that the previous accpeted model with two spectral components (blackbody plus Gaussian absorption line) cannot reflect the overall spectral shape. A successful fit was achieved by including a second Gaussian absorption line at energy E₂ = 2 × E₁ lending strong support to the cyclotron interpretation of the absorption features in a field of ∼4 × 10¹³ G. The results of spin-phase resolved spectroscopy will be presented elsewhere.

Tatiana Victorovna Shabanova
Title: Slow glitches in the pulsar B1822-09
Abstract: Three slow glitches in the spin rate of the pulsar B1822-09 have been detected at the Pushchino Observatory over the 1995-2004 interval. Characteristic feature of the slow glitches is a gradual increase in the rotation frequency with a long time-scale of 200-300 days. This is accompanied by a rapid decrease in the magnitude of the frequency derivative by 1-2 per cent of the initial value and a subsequent exponential increase back to its initial value with the same time-scale. An obvious relaxation in frequency after a slow glitch is not observed. The size of a slow glitch after a span of a few years is moderate, with a fractional increase of 20×10^-9. It seems more likely that slow glitches in the rotation frequency of the pulsar may be caused by changes in magnetosphere structure. The Pushchino timing observations of this pulsar are continued till now.

Luigi Stella
Title: Gravitational Radiation from Newborn Magnetars
Abstract: We show here that the enormous energy liberated in the 2004 December 27 giant flare from SGR 1806-20 (∼ 5 × 10⁴⁶ erg), together with the likely recurrence time of such events, requires an internal field strength of ≥ 10¹⁶ G. Toroidal magnetic fields of this strength are within an order of magnitude of the maximum fields that can be generated in the core of differentially-rotating neutron stars immediately after their formation, if their initial spin period is of a few milliseconds. A substantial deformation of the neutron star is induced by these magnetic fields and, provided the deformation axis is offset from the spin axis, a newborn fast-spinning magnetar would radiate for a few weeks a strong gravitational wave signal the frequency of which (∼ 0.5-2 kHz range) decreases in time. The signal from a newborn magnetar with internal field > 10^16.5 G could be detected with Advanced LIGO-class detectors up to the distance of the Virgo cluster (characteristic amplitude h_c ∼ 10^-21). Magnetars are expected to form in Virgo at a rate > 1 yr^-1. If a fraction of these have sufficiently high internal magnetic field, then newborn magnetars constitute a promising new class of gravitational wave emitters.

Valery F. Suleimanov, K. Werner
Title: Importance of Compton scattering to radiation spectra of isolated neutron stars
Abstract: Model atmospheres of isolated neutron stars with low magnetic field are calculated with Compton scattering taking into account. Radiation spectra computed with Compton scattering are softer than computed with Thomson scattering at high energies (E > 5 kev) for hot (T_eff > 10⁶ K) atmospheres with hydrogen-helium composition. Compton scattering is more significant to models with low surface gravity, This fact gives a new tool to the measurement of neutron star compactness. Compton scattering is less important to models with solar abundance of heavy elements and is not changing the spectra of iron model atmospheres.

Cindy Tam
Title: Chandra Monitoring of the Candidate Anomalous X-ray Pulsar AX J1845-0258
Abstract: The population of clearly identified anomalous X-ray pulsars has recently grown to seven, however, one candidate AXP still eludes confirmation. Here, we present a set of seven Chandra/ACIS-S observations of the transient 7-s pulsar AX J1845-0258, obtained during 2003. The goal of our analysis is to characterise the quiescent spectral and timing properties of this elusive AXP candidate, which was originally discovered in 1993 ASCA observations, but whose pulsed signal has not been detected since. The latest Chandra observations reveal a faint X-ray point source within the ASCA error circle, which we tentatively identify as the quiescent AXP. Its spectrum is well-described by an absorbed single-component blackbody (kT ∼ 2.0 keV) or power law (Gamma ∼ 1.0) that is steady in flux on timescales of at least months, but fainter than AX J1845-0258 was during its 1993 period of X-ray enhancement by at least a factor of 16. Compared to the outburst spectrum of AX J1845-0258 (kT ∼ 0.6 keV), the Chandra source is considerably harder: if truly the counterpart, then its spectral behaviour is contrary to that seen in the other confirmed transient AXP XTE J1810-197, which softened in quiescence from kT ∼ 0.6 keV to ∼ 0.18 keV. This unexpected result prompts us to discuss the likelihood that we have observed an unrelated source and that the quiescent AXP is even fainter in flux.

Andrea Tiengo
Title: Long term spectral variability in the Soft Gamma-ray Repeater SGR 1900+14
Abstract: We present a systematic analysis of all the BeppoSAX data of SGR1900+14. The seven observations spanning 5 years show that the source was brighter than usual on two occasions: ∼20 days after the August 1998 giant flare and during the 10⁵ s long X-afterglow following the April 2001 intermediate flare. In the latter case, we explore the possibility of describing the observed short term spectral evolution only with a change of the temperature of the blackbody component. In the only BeppoSAX observation performed before the giant flare, the spectrum of the SGR1900+14 persistent emission was significantly harder and was possibly detected for the first time above 10 keV. In the last BeppoSAX observation (April 2002) the flux was at least a factor 1.2 below the historical level, suggesting that the source was entering the long quiescent period observed up to date.

Andrey Timokhin
Title: Could we see oscillations of the neutron star after the glitch in pulsar?
Abstract: Pulsar “standard model” of rotating magnetized conducting sphere surrounded by plasma is generalized in its essential parts for the case of oscillating star. Goldreich-Julian charge density, electromagnetic energy losses as well as polar cap scenario of particle accelerations are considered. The main attention in this work is drawn to distortion of pulsar magnetosphere by neutron star oscillations. The changes in the Goldreich-Julian charge density due to star pulsations for oscillation modes with high harmonic numbers (l,m) could be substantially large and will lead to significant distortion of accelerating electric field in pulsar polar cap. This results in remarkable changes of individual pulse profiles of radiopulsars. It is shown, that for moderately optimistic scenario of NS oscillations excitation by the glitch, such changes in pulsar radiation could be detected by contemporary radiotelescopes. This formalism can be applied to the magnetosphere of magnetar as well.

Andrey Timokhin
Title: Force-free magnetosphere of aligned rotator
Abstract: Review in details properties of stationary force-free magnetosphere of aligned rotator assuming the last closed field line lying in equatorial plane at large distances from pulsar. There is a set of solutions with different sizes of the closed magnetic field line zone. I discuss the role of electron-positron cascades in supporting of the force-free magnetosphere and argue that the closed field line zone should grow with time slower than the light cylinder. This yield the pulsar breaking index less than 3. However, models of aligned rotator magnetosphere with widely accepted configuration of magnetic field have serious difficulties. A solutions of this problem is suggested. I argue that in any case pulsar energy losses should evolve with time differently than predicted by the magnetodipolar formula.

Brigitte Tome
Title: Detectability of gravitational waves from the r-mode instability in newly-born neutron stars: The role of differential rotation
Abstract: Recently, it was shown that differential rotation is an unavoidable feature of r-modes. We investigate the influence of this differential rotation on the detectability of gravitational waves emitted by a newly born, hot, rapidly-rotating neutron star, as it spins down due to the r-mode instability. We conclude that gravitational radiation could be detected by advanced laser interferometer detectors if the amount of differential rotation at the time the r-mode instability becomes active is not too high.

Aldo Treves (A. Treves, S. Campana, M. Chieregato, T. Nelson and M. Orio)
Title: Are Transient Blank Field Sources the Hiccups of Middle Aged Neutron Stars?
Abstract: The analysis of the ROSAT HRI Wavelet Catalogue, yielded four sources without optical counterparts (Blank Field Sources, Chieregato et al 2005). The significance of the sources is > 4 sigma, and the lower limit of f_X/f_opt is 40. Three of the sources are transient and one is steady. We present new optical limits on two of the transient sources based on WIYN 3.5 m telescope observations. Further optical and X-ray observations are in progress. Supposing that the three transients are real, we evaluate the total number of such sources in the Galaxy per year, and suggest that they may be related to neutron stars in a post pulsar phase, and specifically with the recently reported transient pulsars (McLaughin et al 2005).

Alexander Turbiner
Title: Molecular systems in a strong magnetic field
Abstract: Overview of one-two electron molecular systems made out of protons and/or α-particles in a strong magnetic field B > 10⁹ G is presented. A particlar emphasis is given to the one-electron exotic ions H₃⁺⁺ (pppe), He₂³⁺ (ααe) and to two-electron ions H₃⁺ (pppee), He₂⁺⁺ (ααee). Quantitative studies in a strong magnetic field are very complicated technically. Novel approach to the few-electron Coulomb systems in magnetic field, which provides very accurate results, based on variational calculus with physically relevant trial functions is briefly described.

Marten H van Kerkwijk
Title: Spectra of isolated neutron stars
Abstract: Over the last year, photospheric absorption features - likely due to hydrogen in strongly magnetized atmospheres - have been found in X-ray spectra taken with XMM and Chandra for three nearby neutron stars. I will describe what we have learned from those observations, in particular from our large, 300 ks Chandra programme, will compare inferred magnetic field strengths with those determined from timing observations, and will discuss what constraints we find on the atmospheres and interiors of these neutron stars.

Joseph E. Ventura
Title: Thermal History of Magnetars
Abstract: Soft Gamma Repeaters (SGR), and Anomalous X-ray Pulsars (AXP) are currently thought to be magnetars. Their persistant X-ray luminosity of ∼ 10³⁵ erg, well exceeds their spin-down energy release. They occasionally exhibit episodes of intense bursting activity as well as transient changes in their persistent emission. We examine the energetics of these transient events which allow us to draw conclusions on the long term heating of the neutron star.

Juan C Lopez Vieyra
Title: The exotic ion H₃⁺⁺ in strong magnetic fields
Abstract: It is shown that the exotic system H₃⁺⁺, which does not exist without magnetic field, can exist in linear configuration aligned with a magnetic field B › 10¹⁰ G. It is also shown that the excited electronic states of positive z-parity 1σ_g, 1π_u, 1δ_g are bound states while the states with negative z-parity 1σ_u, 1π_g, 1δ_u, are repulsive. At B › 10¹³ G the ion H₃⁺⁺ is the one-electron proton-made stable system with the lowest total energy.

Juan C Lopez Vieyra
Title: Two-electron molecules H₂ and H₃⁺ in a strong magnetic field
Abstract: The lowest electronic states of two-electron molecular systems H₂ and H₃⁺ in linear parallel configuration in a strong magnetic field > 10⁹ G are investigated. Evolution of the ground state with a magnetic field increase is studied. It is shown that both systems are stable and for B > 10¹¹ G their ground state is 3 π.

Jacco Vink
Title: Magnetars in supernova remnants and magnetar formation scenarios
Abstract: It is now generally accepted that Anomalous X-ray Pulsars (AXPs) and Soft Gamma-ray Repeaters (SGRs) are magnetars, i.e. neutron stars with surface magnetic fields of 10¹⁴-10¹⁵ G. The origin of this magnetic field is uncertain, but one of the hypotheses is that magnetars are born with an initial spin period close to the break-up limit (< 1 ms), which results in a powerful dynamo action, greatly amplifying the seed magnetic field. A neutron star spinning at such a rate has a rotational energy in excess of 10⁵² erg, and part of that energy will power the supernova through rapid magnetic breaking. In other words it is expected that if magnetars are born with periods of ∼1 ms their supernova remnants should be very energetic. However, we have investigated two supernova remnants which contain magnetars, Kes 73 (1E 1841-045) and N49 (SGR 0526-66), and they appear to be the results of explosions with the canonical supernova explosion energy of 10⁵¹ erg. The energy of third one, CTB109 (1E2259+586), recently appeared in the literature and was also ∼ 10⁵¹ erg. Converting the energy to an initial rotation period suggests that the initial period was longer than ∼6 ms. This suggests, therefore, that at least the magnetars in those supernova remnants are likely to have been formed from progenitors with a high magnetic field, rather than with a high angular momentum.

Jacco Vink
Title: The peculiar spectral evolution of RX J0720.4-3125
Abstract: RX J720.4-3125 is one of the brightest radio quiet, isolated neutron stars, whose optical and X-ray emission is dominated by thermal radiation from the neutron star surface. The archetypal neutron star of this class is RX J1856.5-3754, which has a featureless black body spectrum in X-rays. Several others, however, are now known to have broad absorption line features in their X-ray spectra. Early observations of RX J0720.4-3125 indicated a feature less X-ray spectrum, similar to RX J1856.5-3754. However, XMM-Newton observations taken in the course of the last five years indicate that the spectrum is slowly changing: from 2000 to 2004 the black-body temperature increased from kT∼85 eV to ∼95 eV, and simultaneously a broad absorption line feature around 300 eV became apparent, increasing its equivalent width with time (in hindsight it was also, weakly, present in 2000). So it now resembles more a source like RX J1605.3+3249, which has a broad line absorption feature. Some properties of the neutron star must be changing, resulting in spectral changes. The tight correlation between black-body temperature and absorption line depth suggests, in fact, that it is one single property, which perhaps also determines why RX J1605 has and RX J1856 does not have an absorption feature. However, it is not yet known which property that is, and what is the physical mechanism behind it. It may be that the magnetic field is evolving, but it may also be that as a result of precession our viewing angle toward the putative hot spot is changing. In that light it is interesting that the last two XMM-Newton observations indicate that the spectral is slowly evolving back: temperature and absorption line depth are decreasing. I will present the latest results, including the new XMM-Newton DDT observation of November 2005.

Stefanie Wachter
Title: Spitzer Observations of SGR and AXP Environments
Abstract: Both Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) are thought to be manifestations of magnetars. However, the specific physical characteristics that differentiate the two classes of objects remain unclear. There is some evidence that the progenitors of these sources and/or the environment in which they form might influence the type of phenomena the resulting magnetar displays. Several of the AXPs appear to be associated with supernova remnants, while embedded clusters of massive stars have been found in the immediate vicinity of some SGRs. Since both AXPs and SGRs are distributed close to the Galactic plane, high extinction makes studies in the optical difficult. We will present results from our Spitzer program aimed at probing the environmental factors that might contribute to the difference in the observed characteristics between AXPs and SGRs.

Frederick M Walter (F. M. Walter, J. Faherty, G. Pavlov, J. Lattimer)
Title: The Trigonometric Parallax of Geminga. II. Consequences.
Abstract: The radiation radius of neutron stars is a fundamental observational property that constrains not only the astrophysical properties (e.g., luminosity), but also the interior equation of state and the physics of condensed matter. As the closest of the gamma ray pulsars, Geminga is of considerable astrophysical interest. Geminga is the prototype of the isolated multiwavelength pulsars. It has a 237 msec pulse period from the gamma rays to (perhaps) MHz radio frequencies. Geminga is thought to have been born in the Orion OB1a association some 340,000 years ago. The distance is estimated at a few hundred pc; Caraveo et al (1996) published a 157⁺⁵⁹_-34 pc distance that has yet to be confirmed. We obtained four images of Geminga using the Advanced Camera for Surveys Wide Field Camera on the Hubble Space Telescope, over the 18 months from October 2003 through March 2005, near the times of maximum parallactic shift. We observed in the F555W filter to optimize the number of background stars and the brightness of the pulsar. In the first paper in this series (Faherty et al), we lay out the techniques for doing astrometry with the ACS/WFC. Here we will use the parallax measurement to estimate the radiation radius of the neutron stars. We will discuss its three dimensional space motion, and its true luminosity.

Anna L. Watts
Title: High frequency oscillations during magnetar flares: evidence for neutron star vibrations
Abstract: The recent discovery of high frequency oscillations during giant flares from SGR 1806-20 and SGR 1900+14 may be the first direct detection of vibrations in a neutron star crust. If this interpretation is correct it offers a novel means of testing the neutron star equation of state, crustal breaking strain, and magnetic field configuration. I will present the results of timing analysis of the SGR 1806-20 flare using data from RHESSI, and report the progress of theoretical efforts to understand the vibrations.

Martin C. Weisskopf
Title: Chandra Observations of Isolated Neutron Stars
Abstract: We present a review of the first six years of Chandra X-ray Observatory observations of isolated neutron stars. The outstanding spatial and spectral resolution of this great observatory have allowed for observations of unprecedented clarity and accuracy. Many of these observations have provided new insights into neutron star physics. We present a (biased) overview of six years of these observations, highlighting new discoveries made possible by the Observatory’s unique capabilities.

Klaus Werner
Title: Non-LTE modeling of Supernova Fallback Disks
Abstract: Fallback disks are expected to form around young neutron stars after a supernova explosion. Such disks have been invoked around AXPs and central compact objects in SNRs. A fallback disk model has been proposed for SGRs, too. However, the existence of these disks has never been confirmed observationally. This might have been caused by inadequate disk models. It is our aim to model the emission spectra of fallback disks more realistically. We assume an (irradiated) alpha-disk that is divided in concentric rings. For each ring we solve the radiation transfer equation under non-LTE conditions in order to achieve a self-consistent vertical disk structure. Our model code is able to deal with arbitrary chemical compositions. The models shall be compared to observations.

Peter M Woods
Title: Evidence for a Binary Companion to the Enigmatic Compact Central Object 1E 1207.4-5209
Abstract: Located in the supernova remnant G296.5+10.0, 1E 1207.4-5209 is a 0.424 s period X-ray pulsar that exhibits strong absorption lines in its energy spectrum. The physical origin of the spectral features in 1E1207.4-5209 and more generally, the absence of similar features in other radio-quiet neutron stars remains a mystery. Another, possibly related, anomalous property of 1E 1207.4-5209 is its non-monotonic spin frequency evolution. Zavlin, Pavlov & Sanwal (2004) proposed that the irregular spin-down was caused by either (i) frequent, recurrent glitches, (ii) the presence of a fall-back disk or (iii) a binary companion. Here, we report on a sequence of seven XMM-Newton observations of 1E 1207.4-5209 performed during a 40 day window between 2005 June 22 and July 31. Due to unanticipated phase noise, we identified three statistically-acceptable phase-coherent timing solutions with frequency time derivatives of +0.9, -2.6, and +1.6 × 10^-12 Hz/s (listed in descending order of significance). We concluded that the local frequency derivative during our XMM-Newton observing campaign differs from the long-term spin-down rate by more than an order of magnitude. This measurement strongly supports the binary interpretation for the observed spin irregularities in 1E 1207.4-5209. We identified a family of orbital solutions that are consistent with our phase-connected solution as well as all archival data. We will discuss possible orbital solutions, prospects for constraining binary parameters with future observations, and consequences for the nature of 1E 1207.4-5209.

Kinwah Wu
Title: QCD phase transition in neutron stars and gamma-ray bursts
Abstract: The quantum chromodynamics phase diagram shows the phase transitions which can take place in matter at different temperatures and densities. In this work we discuss the possibility that gamma-ray bursts might result from a phase change in the interior of a neutron star and calculate the energy released in the conversion of a metastable star into a stable star. We consider several different initial and several different final configurations. Initial metastable stars are taken as hadronic, hybrid and quark stars with unpaired quarks and possible stable stars are hybrid and quark stars, both with unpaired and paired phase in order to study the deconfinement phase transition and normal quark matter -superconducting quark matter phase transition within a large number of relativistic models used to describe compact stars. The models used for the hadron matter are the non-linear Walecka model (NLWM) and the quark-meson coupling model (QMC) with and without hyperons. For the quark matter we have used the MIT bag model, the bag model with paired quarks to which we refer as the CFL phase model and the Nambu-Jona-Lasinio (NJL) model. Within this mechanism we obtain energies of the order of 10⁵⁰-10⁵³ erg, accounting for both long and short gamma ray bursts.

Silvia Zane
Title: Neutron star surface emission: beyond the dipole model
Abstract: Recent Chandra and XMM-Newton observations of a number of X-ray “dim” pulsating neutron stars revealed quite unexpected features in the emission from these sources. Their soft thermal spectrum, believed to originate directly from the star surface, shows evidence for a phase-varying absorption line at some hundred eVs. The pulse modulation is relatively large (pulsed fractions in the range ∼ 12%-35%), the pulse shape is often non-sinusoidal, and the hard X-ray color appears to be anti-correlated in phase with the total emission. Moreover, the prototype of this class, RX J0720.4-3125, has been found to undergo rather sensible changes both in its spectral and timing properties over a timescale of a few years. All these new findings are difficult to reconcile with the standard picture of a cooling neutron star endowed with a purely dipolar magnetic field. The currently proposed one-dimensional magnetic atmosphere models represent a substantial improvement with respect to a simple blackbody representation, inasmuch they include most of the relevant physics, but a large amount of work remains to be done before they can be claimed to be fully satisfactory. In fact, models available so far only account for a single temperature and a single value of the magnetic field strength and inclination. The radiative transfer computations are basically plane-parallel and refer to a single patch of surface with fixed B,T; the star surface is then assumed to be made of patches all equal to each other. Here we present more realistic models, where the effects of different NS thermal and magnetic surface distributions on the observed spectra and lightcurves are accounted for. We show how a dipolar+quadrupolar star-centered field influences the properties of the observed lightcurves and we present results that account self-consistently for more realistic toroidal and poloidal crustal field configurations.

Vyacheslav Zavlin
Title: X-ray emission from millisecond pulsars
Abstract: Isolated (solitary or non-accreting) millisecond pulsars with observed X-ray emission can be divided in two distinct groups: those emitting nonthermal (magnetospheric) radiation and pulsars with the bulk of X-rays of a thermal origin, presumably emitted from small hot spots around the magnetic poles on the neutron star surface (polar caps). I will discuss properties of X-ray emission detected with Chandra and XMM-Newton from a number of millisecond pulsars, with emphasis on those of the thermal component, and compare them with predictions of radio pulsar models.

Sergey V. Zharikov
Title: The optical spectrum of the middle-age pulsar PSR B0656+14
Abstract: We obtained an optical spectrum of the isolated middle-age pulsar PSR B0656+14 with S/N > ∼3 for the continuum in the range from 4300Å to about 9000Å using FORS2 instrument at the ESO VLT/UT1 telescope. We will present the analysis of the obtained data together with our and available UV-optical-IR photometry. The evolution of the optical radiation efficiency with the pulsar dynamical age will be discussed.