X-ray emission from dwarf novae

Abstract

The conditions under which the boundary layer between an accretion disk and a white dwarf can emit hard X-rays is examined with particular application to the observations of X-rays from dwarf novae. It is argued that for low accretion rates (no more than about 10 to the 16th g/s) hard X-ray emission is possible with temperatures up to about 200 million K. For higher accretion rates, hard X-ray emission is suppressed, and most of the radiation is emitted as soft X-rays with a temperature of about 200,000 to 500,000.