2013/05/08 by Fabio Pintore, Pintore, Fabio, Paolo Esposito +8
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Stellar, planetary, and galactic studies #astro-ph.CO #astro-ph.HE
paper · pdf · doi:10.48550/arxiv.1305.1862
2 pages, 1 figure. Proceeding of the conference "X-ray Astronomy: towards the next 50 years!" (Milano, 1-5 October 2012), to be published on Memorie della Società Astronomica Italiana
arxiv created 2013/05/08 · openalex publication_date 2013/05/08 · arxiv updated 2013/05/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a multi-wavelenght study of the recently discovered Ultraluminous X-ray transient XMMUJ004243.6+412519 (ULX2 hereafter) in M31, based on Swift data and the 1.8-m Copernico Telescope in Asiago (Italy). Undetected until January 2012, the source suddenly showed a powerful X-ray emission with a luminosity of 1e38 erg/s (assuming a distance of 780 kpc). In the following weeks, its luminosity overcame 1e39 erg/s, remaining fairly constant for at least 40 days and fading below 1e38 erg/s in the next 200 days. The spectrum can be well described by a single multi-color disk blackbody model which progressively softened during the decay (from kT=0.9 keV to 0.4 keV). No emission from ULX2 was detected down to 22 mag in the optical band and to 23-24 mag in the near ultraviolet. We compare its properties with those of other known ULXs and Galactic black hole transients, finding more similarities with the latter.