Structure of steady state accretion shocks with several cooling functions: Closed integral-form solution

Abstract

We present, for the first time, a closed integral-form solution to the accretion shock structures for the case where the cooling is due to optically thin bremsstrahlung emission and a series of power-law cooling functions of density and temperature. Our results can provide useful checks on numerical calculations and simple accurate estimates for valuable parameters such as the shock height. For the case where the cooling rate j = (2/3)Arho<SUP>2</SUP>(P/rho)<SUP>1/2</SUP>(1 + epsilon <SUB>s</SUB>(P/P<SUB>s</SUB><SUP>alpha</SUP>(rho<SUB>s</SUB>/rho)<SUP>beta</SUP>), we find that a substantial amount of the accretion energy is released at the base of the accretion shock in the form of bremsstrahlung radiation. This implies that for a cyclotron-dominated shock (qualitatively given by alpha = 2.0, beta = 3.85, and epsilon<SUB>s</SUB> is much greater than 1), bremsstrahlung cooling still plays a crucial role in determining the shock structure. Our results are shown to be consistent with detailed numerical calculations.