Thermal emission from the stellar-mass black hole binary XTE J1118+480 in the low/hard state

Abstract

We report on the detection of a thermal-disk component from the stellar-mass black hole binary XTE J1118+480 in the canonical low/hard state. The presence of a thermal component with a temperature of approximately 0.21keV in the Chandra spectra of XTE J1118+480 is found at more than the 14 sigma confidence level. Based on this evidence we argue that the accretion disk in XTE J1118+480 is not truncated far from the central black hole in contrast with previous claims.