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Chandra and Hubble Study of a New Transient X-ray Source in M31

Benjamin F. Williams·Michael R. Garcia·Jeffrey E. McClintock·Frank A. Primini·Stephen S. Murray
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Abstract

We present X-ray and optical observations of a new transient X-ray source in M31 first detected 23-May-2004 at R.A.=00:43:09.940 +/- 0.65'', Dec.=41:23:32.49 +/- 0.66''. The X-ray lightcurve shows two peaks separated by several months, reminiscent of many Galactic X-ray novae. The location and X-ray spectrum of the source suggest it is a low mass X-ray binary (LMXB). Follow-up HST ACS observations of the location both during and after the outburst provide a high-confidence detection of variability for one star within the X-ray position error ellipse. This star has $Δ$B ~ 1 mag, and there is only a ~1% chance of finding such a variable in the error ellipse. We consider this star a good candidate for the optical counterpart of the X-ray source. The luminosity of this candidate provides a prediction for the orbital period of the system of 2.3$^{+3.7}_{-1.2}$ days.

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Benjamin F. Williams, Michael R. Garcia, Jeffrey E. McClintock, Frank A. Primini, Stephen S. Murray. 2005-09-07. Chandra and Hubble Study of a New Transient X-ray Source in M31. https://doi.org/10.1086/444369

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