Chandra detection of outburst from M31 binary CXOM31 J004321.1+411751
ATel #2294; N. Nooraee (Dublin Institute for Advanced Studies, University College Cork), P. Callanan (UCC), M. Garcia (SAO)
on 13 Nov 2009; 17:56 UT
Credential Certification: Michael R. Garcia (garcia@cfa.harvard.edu)
Subjects: X-ray, Binary, Black Hole, Neutron Star, Transient
Based on a 5ks Chandra ACIS-I observation of M31 on Nov 11 2009,
we report a dramatic brightening of CXOM31 J004321.1+411751,
[aka r3-7 (Kong et al. 2002 ApJ 577, 738),
source 437 (Pietsch, Freyberg, and Haberl 2005 A&A 434, 483),
RX J0043.3+4117 (Supper et al. 2001 A&A 373, 63)].
The spectrum on Nov 11 can be well fit with a power law with
photon index 2.1 +/- 0.2 and Nh consistent with the Galactic
value of 7E20 cm^-2. The observed luminosity over 0.5-10.0 keV
assuming a 780 kpc to M31 is 2.6E37 ergs/sec.
Observations on Sept 18, Sept 25, and Oct 22 2009
found the source ~20x fainter at luminosity of 1.3E36 ergs/sec,
assuming the same spectral shape.
This source has previously been known as variable, but the high level of variability
found here may suggest an eclipse or a true transient outburst. The average luminosity
seen in earlier Chandra observations was 3.7E36 ergs/sec (Kong et al. 2002).