RX J0042.3+4115: a stellar mass black hole binary identified in M 31, and other papers

Abstract

In this work we have previously identified low mass X-ray binaries (LMXBs) in XMM-Newton observations of M 31 from their characteristic power density spectra (PDS). These PDS were characterised by a broken power law, with the spectral index changing from ∼0 to ∼1 at a break frequency in the range 0.01−1 Hz, and signify LMXBs in their low accretion-rate state (van der Klis 1994, ApJ, 92, 511). However, the observed PDS were false positives resulting from the improper treatment of non-simultaneous lightcurves; the corrected PDS are featureless (see Barnard et al. 2007, A&A, 469, 875, for details). As a result, there is no evidence for black hole primaries in the subjects of these papers.