出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：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 F210keV 1–21011 erg cm2 s1 (unabsorbed), corresponding to luminosities of a few 1033 to a few 1034 erg s1. Finally, the duty-cycle of inactivity ranges between 19 and 55 %.
