Abstract:
We investigate two-temperature accretion flows onto strongly magnetized compact stars. Matter is accreted in the form of an
accretion disc upto the disc radius (rd), where, the magnetic pressure exceeds both the gas and ram pressure and thereafter the
matter is channelled along the field lines onto the poles. We solve the equations of motion self-consistently along the field lines,
incorporating radiative processes like bremsstrahlung, synchrotron, and inverse-comptonization. For a given set of constants of
motion, the equations of motion do not produce unique transonic solution. Following the second law of thermodynamics, the
solution with the highest entropy is selected and thereby eliminating the degeneracy in solution. We study the properties of these
solutions and obtain corresponding spectra as a function of the magnetic field (B∗), spin period (P) and accretion rate of the star
(M˙ ). A primary shock is always formed just near the surface. The enhanced radiative processes in this post-shock region slows
down the matter and it finally settles on the surface of the star. This post-shock region contributes to 99.99 per cent of the
total luminosity obtained from the accretion flow. It is still important to study the full accretion flow because secondary shocks
may be present for some combination of B∗, P, and M˙ in addition to primary shocks. We find that secondary shocks, if present,
produce an extended emission at higher energies in the spectra.
