2011/03/30 by P. Romano, S. Vercellone, Romano, P. +19
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE) #astro-ph.HE
paper · pdf · doi:10.48550/arxiv.1103.6036
Proceedings of the 25th Texas Symposium on Relativistic Astrophysics, December 6-10, 2010, Heidelberg, Germany
arxiv created 2011/03/30 · openalex publication_date 2011/03/30 · arxiv updated 2011/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present an overview of our Supergiant Fast X-ray Transients (SFXT) project, that started in 2007, by highlighting the unique observational contribution Swift is giving to this exciting new field. By means of outburst detection with Swift/BAT and follow-up with Swift/XRT, we demonstrated that while the brightest phase of the outburst only lasts a few hours, further significant activity is observed at lower fluxes for a considerably longer (weeks) time. After intense monitoring with Swift/XRT, we now have a firm estimate of the time SFXTs spend in each phase. The 4 SFXTs we monitored for 1-2 years spend between 3 and 5 % of the time in bright outbursts. The most most probable flux level at which a random observation will find these sources, when detected, is F(2-10 keV) ~ 1-2E-11 erg cm-2 s-1 (unabsorbed), corresponding to luminosities of a few 1033 to a few 1034 erg s-1. Finally, the duty-cycle of inactivity ranges between 19 and 55 %.