Article Dans Une Revue The Astrophysical Journal Année : 2013

A CHANDRA /HETGS CENSUS OF X-RAY VARIABILITY FROM Sgr A* DURING 2012

Résumé

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 ~1034 erg s-1 to 2 × 1035 erg s-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}_{-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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hal-02326976 , version 1 (24-01-2025)

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J. Neilsen,, A. Nowak, M., C. Gammie,, J. Dexter,, S. Markoff,, et al.. A CHANDRA /HETGS CENSUS OF X-RAY VARIABILITY FROM Sgr A* DURING 2012. The Astrophysical Journal, 2013, 774 (1), pp.42. ⟨10.1088/0004-637X/774/1/42⟩. ⟨hal-02326976⟩
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