Query : 2011A&A...526A..50B

2011A&A...526A..50B - Astronomy and Astrophysics, volume 526A, 50-50 (2011/2-1)

Observations of the recurrent M 31 transient XMMU J004215.8+411924 with Swift, Chandra, HST, and EINSTEIN.


Abstract (from CDS):

The transient X-ray source XMMU J004215.8+411924 within M31 was found to be in outburst again in the 2010 May 27 Chandra observation. We present results from our four Chandra and seven Swift observations that covered this outburst. X-ray transient behaviour is generally caused by one of two things: mass accretion from a high mass companion during some restricted phase range in the orbital cycle, or disc instability in a low mass system. We aim to exploit Einstein, HST, Chandra and Swift observations to determine the nature of XMMU J004215.8+411924. We model the 2010 May spectrum, and use the results to convert from intensity to counts in the fainter Chandra observations, as well as the Swift observations; these data are used to create a lightcurve. We also estimate the flux in the 1979 January 13 Einstein observation. Additionally, we search for an optical counterpart in HST data. Our best X-ray positions from the 2006 and 2010 outbursts are 0.3'' apart, and 1.6'' from the Einstein source; these outbursts are likely to come from the same star system. We see no evidence for an optical counterpart with mB≲25.5; this new limit is 3.5mag fainter than the existing one. Furthermore, we see no V band counterpart with mV≲26. The local absorption is ∼7 times higher than the Galactic line-of-sight, and provides ∼2mag of extinction in the V band. Hence MV>-0.5. Fits to the X-ray emission spectrum suggest a black hole primary. We find that XMMU J004215.8+411924 is most likely to be a transient LMXB, rather than a HMXB as originaly proposed. The nature of the primary is unclear, although we argue that a black hole is likely.

Abstract Copyright:

Journal keyword(s): X-rays: general - X-rays: binaries - galaxies: individual: M31

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 XMMU J004215.8+411924 X 00 42 15.88 +41 19 24.4           ~ 8 0
2 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 12169 1
3 CXOM31 J004253.1+411422 ULX 00 42 53.15 +41 14 22.9           ~ 24 0
4 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10599 1

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