Chandra and FUSE Detections of the WHIM: locally and at z > 0
The Local Group WHIM (Nicastro et al., 2002, ApJ, 573, 157; Nicastro et al., 2003, Nature, 421, 719) | ||
The “Truly” Intervening WHIM | ||
Mkn 421 (Nicastro et al., 2003, in preparation) | ||
Future prospects (Pharos) |
Chandra and FUSE Spectra of PKS 2155-304
Equivalent Width Ratios Diagnostics
All absorption Lines fall in the linear branch of the Curves of Growth (CoG) | |
č EW µ Ion Column Density : | |
EW ratios µ Ionization Balance: | |
Assuming a transverse size of 1´[H/O]0.3 Mpc |
OVI Velocity Distribution in the LSR
HV-OVI Absorbers are at rest in the LGSR | |
logT = 5.8; d = 20-30 | |
[Ne/O] = 2.5 [Ne/O] | |
Total Mass = | |
(0.6-2)´1012 [H/O]0.3M | |
Not in Milky Way Halo | |
Fits Predictions for Warm-Hot IGM | |
Dusty IGM? | |
Can Bind the Local Group |
Detecting z > 0 WHIM filaments is harder because of random orientation: lines of sight to background sources cross only a portion of the filament. | |
Until very recently, only 3 tentative detections have been claimed, along 2 different lines of sight (Fang et al., 2002, Mathur et al., 2002). | |
Exceptionally high quality X-ray spectra of background AGN are needed, implying exposures of Ms on the brightest blazars in their normal state. |
Mkn 421: Chandra 1st Order Dispersed Spectrum
Chandra and Newton-XMM detection of the Local Group WHIM Filament | |
Kinematics of the HV-OVI unambiguously locates them in the Local Group | |
Chandra ToO of Mkn 421 probes unprecedented NOVII and detects 1-2 trees in the “X-ray Forest”. | |
Based on that detection: dNOVII/dz = 75 (cf. dNOVI/dz = 20, Tripp & Savage, 2000): the majority of baryons at z < 2. |
Next 2-4 years: collect data from 12 sightlines towards blazars in outburst: up to z = 0.5: č dNWHIM/dz, Wb, TWHIM(z<0.5), dTWHIM/dz, dZ/dz | |
Long Term: mapping the WHIM up to z=2: needs high throughput and spextral resolution in X-ray: Constellation-X (R > 1000, A = 2000 cm2), and XEUS (R > 400, A = 30 m2) | |
Pharos: (Elvis, Fiore & the CWE team, 2002 SPIE, astro-ph/0303444), Midex concept (CfA, Obs. Rome, JHU): R > 5000, A = 1000 cm2, Coverage: 12-150 Ĺ. Slew on source in < 2-3 min.: about 20 Soft-GRB per year with F = 10-5 erg cm-2 (> 10 Ms on the brightest QSOs at z = 1-2). | |