Rapid Response Galactic X-ray Transient Follow-up with Swift
Abstract
Understanding the variety of Galactic X-ray transients requires the ability to perform rapid response observations, to catch both the rapid rises, and fast decay of these objects. Swift, although primarily designed for the discovery and follow-up of Gamma-ray bursts, has proven to be very effective at discovery, localization and rapid and long term follow-up of Galactic X-ray Transients. Here we present two different examples of "hard to catch” events where Swift's unique rapid response, low-overhead and broadband sensitive observing capabilities have shed new light on both the rise and fall of X-ray transients events. Mill-second pulsars: Swift has monitored the rapid decline to quiescence of accreting millisecond pulsars, such as SAX J1808.4-3658, one of the only millisecond pulsars observed transitioning into quiescence with a sensitive focused X-ray telescope. As these outbursts often end abruptly, only regular monitoring in outburst of the sources will allow us to catch these elusive events, and in the post-RXTE era, only Swift is capable of this task. Stellar mass black-hole binaries: The triggering capabilities of Swift/BAT have allowed us to track the evolution of bright X-ray outbursts from stellar mass black-hole binaries in our galaxy, with example of MAXI J1659-152 shown here, from the beginning of the outburst with new fidelity. Modeling of the X-ray spectrum allows us to track the evolution of the accretion disk in these systems from earlier than previously possible, due to the faster response time to the outburst, and the low energy sensitivity of Swift's X-ray telescope allowing for more sensitive measurements of cooler (inner disk kT<0.5 keV) accretion disks than RXTE. In addition, Swift monitoring of the decay into quiescence of these black hole binaries, can help solve the contentious issue of the nature of the accretion disk in the low/hard state.
- Publication:
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American Astronomical Society Meeting Abstracts #219
- Pub Date:
- January 2012
- Bibcode:
- 2012AAS...21915321K