Speaker
Description
I will present the results of our ongoing Swift monitoring of Be/X-ray transients that we started almost ten years ago. We have followed up more than ten galactic systems (i.e., GRO J1008-57, SAX J2103.5+4545, GX 304-1, GRO J1750-27, KS 1947+300) during and after their outbursts. The aim of our monitoring campaigns was to study the process of low-level accretion onto magnetized (10^12-10^13 G) neutron stars, and to determine if neutron-star crust cooling emission could be detected, similar to what was seen for the weak-field accreting neutron stars. What we have found is that these sources show a wide variety of behaviors when they transit to quiescence after their outburst activities: some sources directly transit to quiescence (e.g., GRO J1750-27), others decrease slowly in time (e.g., SAX J2103.5+4545), some of them stay in an intermediate level of 10^34-10^35 erg/s (e.g., GRO J1008-57, GX 304-1), others also show a reflaring activity before turning to quiescence (e.g., KS 1947+300), and one of them show a recurrent decaying low X-ray luminosity (4U 0115+63). We will show our results of the monitoring campaigns and introduce the physics behind these variable behaviors at low X-ray luminosities.
