Constraining the Spectrum of HLX-1 in Outburst
Abstract
HLX-1 currently provides the strongest evidence for the existence of intermediate mass black holes. Previous observations with XMM and an ongoing monitoring campaign with Swift have shown that it undergoes similar spectral state transitions to stellar mass black hole binaries, with large-scale flux variability by a factor of ~100 over timescales of weeks to months. Our most recent Swift observation on August 29th found that it has re-brightened and is currently at Lx~1.3E42 erg/s, compared to Lx~3E40 erg/s only 3 weeks prior to this. The spectrum also appears to be dominated by a soft thermal component. We propose to observe this source with Chandra so as to constrain the spectrum and luminosity and to search for variability that has been detected in other states. We will thus be able to test for the presence of a hard tail in the current spectrum, whether HLX-1 follows the same Lx-Tin relationship as other ULXs, and whether the nH is variable (related to outflows).
- Publication:
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Chandra Proposal
- Pub Date:
- September 2009
- Bibcode:
- 2009cxo..prop.3231F