Description
Supergiant fast X-ray transients (SFXTs) are a new class of high-mass X-ray binaries (HMXBs) discovered thanks to the monitoring of the Galactic plane performed with the INTEGRAL satellite in the last 5 years. To characterize the properties of these sources on timescales of months, we are performing a monitoring campaign with Swift of four SFXTs (IGR J16479-4514, XTE J1739-302, IGR J17544-2619, and AX J1841.0-0536/IGR J18410-0535). We report on the first 4 months of Swift observations, which started on 2007 October 26. We detect low-level X-ray activity in all four SFXTs, which demonstrates that these transient sources accrete matter even outside their outbursts. The X-ray spectra are typically hard, with an average 2-10keV luminosity during this monitoring of about 10^33^-10^34^erg/s. We detected pulsations from the pulsar AX J1841.0-0536/IGR J18410-0535, with a period of 4.7008+/-0.0004s.
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