Slide 38 of 48
Notes:
First we are going to calculate the electron energies required to produce X-rays. To do this, we first assume an equipartition of energy between starlight, cosmic rays and magnetic fields - ie all three have the same energy density in the Galaxy.
Energy density in starlight in the galaxy, U_ph = 10^6 eV /m^3
Thus B = 6 x 10^-10 Tesla.
To produce X-rays, gamma_s^2 = (3 x 10^7) / B
So substituting for B, in X-rays ie for nu_max = 10^18 Hz,
In comparison, we take the case of
1. a supernova remnant has B~1e-7 Tesla, so gamma_s^2 ~ 3e14
2. A neutron star surface has B~1e8 Tesla, so gamma_s^2 ~ 0.3
