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# RX J0042.3+4115: A stellar mass black hole binary identified in M 31

journal contribution
posted on 24.10.2012, 09:21 by R. Barnard, J. P. Osborne, U. Kolb, K. N. Borozdin
Four XMM-Newton X-ray observations of the central region of the Andromeda Galaxy (M 31) have revealed an X-ray source that varies in luminosity over ~ $1{-}3\times 10^{38}$ erg s -1 between observations and also displays significant variability over time-scales of a few hundred seconds. The power density spectra of lightcurves obtained in the 0.3-10 keV energy band from the three EPIC instruments on board XMM-Newton are typical of disc-accreting X-ray binaries at low accretion rates, observed in neutron star binaries only at much lower luminosities (~ 1036 erg s -1). However X-ray binaries with massive black hole primaries have exhibited such power spectra for luminosities >10 38 erg s -1. We discuss alternative possibilities where RX J0042.3+4115 may be a background AGN or foreground object in the field of view, but conclude that it is located within M 31 and hence use the observed power spectra and X-ray luminosities to identify the primary as a black hole candidate.

## Citation

Astronomy & Astrophysics, 2003, 405 (2), pp. 505-511

## Version

VoR (Version of Record)

## Published in

Astronomy & Astrophysics

## Publisher

EDP Sciences for European Southern Observatory (ESO)

0004-6361

2003

24/10/2012

## Publisher version

http://www.aanda.org/articles/aa/abs/2003/26/aah4296/aah4296.html

## Notes

Erratum available at doi: 10.1051/0004-6361:20035661e

English