The transient neutron star X-ray binary KS 1741–293 in outburst and quiescence

Abstract

AbstractKS 1741–293 is a transient neutron star low-mass X-ray binary that is located at an angular distance of ≃20′ from the Galactic center. We map out the historic activity of the source since its discovery in 1989, characterize its most recent X-ray outbursts observed with Swift (2007, 2008, 2010, and 2011), and discuss its quiescent X-ray properties using archival Chandra data. KS 1741–293 is frequently active, exhibiting outbursts that typically reach a 2–10 keV luminosity of LX ≃ 1036 (D/6.2 kpc)2 erg s−1 and last for several weeks–months. However, Swift also captured a very short and weak accretion outburst that had a duration of ≲4 days and did not reach above LX ≃ 5×1034 (D/6.2 kpc)2 erg s−1. The source is detected in quiescence with Chandra at a 2–10 keV luminosity of LX ≃ 2.5×1032 (D/6.2 kpc)2 erg s−1.