A Seyfert-2-like Spectrum in the High-mass X-Ray Binary Microquasar V4641 Sgr
Abstract
We present an analysis of three archival Chandra observations of the black hole V4641 Sgr, performed during a decline into quiescence. The last two observations in the sequence can be modeled with a simple power law. The first spectrum, however, is remarkably similar to spectra observed in Seyfert-2 active galactic nuclei, which arise through a combination of obscuration and reflection from distant material. This spectrum of V4641 Sgr can be fit extremely well with a model including partial-covering absorption and distant reflection. This model recovers a Γ ~= 2.0 power-law incident spectrum, typical of black holes at low Eddington fractions. The implied geometry is plausible in a high-mass X-ray binary like V4641 Sgr, and may be as compelling as explanations invoking Doppler-split line pairs in a jet, and/or unusual Comptonization. We discuss potential implications and means of testing these models.
- Publication:
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The Astrophysical Journal
- Pub Date:
- May 2014
- DOI:
- 10.1088/2041-8205/786/2/L20
- arXiv:
- arXiv:1402.6665
- Bibcode:
- 2014ApJ...786L..20M
- Keywords:
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- accretion;
- accretion disks;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted for publication in ApJ Letters