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|a Gammie, C.
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|a MIT Kavli Institute for Astrophysics and Space Research
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|a Neilsen, Joseph M. G.
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|a Nowak, Michael A.
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|a Houck, John C.
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|a Dexter, J.
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|a Markoff, Sera B.
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|a Haggard, D.
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|a Nayakshin, S.
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|a Wang, Q. D.
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|a Grosso, N.
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|a Porquet, D.
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|a Tomsick, J. A.
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|a Degenaar, N.
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|a Fragile, P. C.
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|a Wijnands, R.
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|a Miller, J. M.
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|a Baganoff, Frederick K.
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|a Neilsen, Joseph M. G.
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|a Nowak, Michael A.
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|a Houck, John C.
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|a A CHANDRA /HETGS CENSUS OF X-RAY VARIABILITY FROM Sgr A* DURING 2012
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|b IOP Publishing,
|c 2015-02-03T19:46:51Z.
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|z Get fulltext
|u http://hdl.handle.net/1721.1/93746
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|a We present the first systematic analysis of the X-ray variability of Sgr A* during the Chandra X-ray Observatory's 2012 Sgr A* X-ray Visionary Project. With 38 High Energy Transmission Grating Spectrometer observations spaced an average of 7 days apart, this unprecedented campaign enables detailed study of the X-ray emission from this supermassive black hole at high spatial, spectral and timing resolution. In 3 Ms of observations, we detect 39 X-ray flares from Sgr A*, lasting from a few hundred seconds to approximately 8 ks, and ranging in 2-10 keV luminosity from ~10[superscript 34] erg s[superscript -1] to 2 × 10[superscript 35] erg s[superscript -1]. Despite tentative evidence for a gap in the distribution of flare peak count rates, there is no evidence for X-ray color differences between faint and bright flares. Our preliminary X-ray flare luminosity distribution dN/dL is consistent with a power law with index -1.9[+0.3 over -0.4]; this is similar to some estimates of Sgr A*'s near-IR flux distribution. The observed flares contribute one-third of the total X-ray output of Sgr A* during the campaign, and as much as 10% of the quiescent X-ray emission could be comprised of weak, undetected flares, which may also contribute high-frequency variability. We argue that flares may be the only source of X-ray emission from the inner accretion flow.
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|a United States. National Aeronautics and Space Administration (Einstein Postdoctoral Fellowship Grant PF2-130097)
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|a en_US
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|a Article
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|t The Astrophysical Journal
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