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

被引：155

作者：

Neilsen, J. ^{[1
,2
]}

Nowak, M. A. ^{[2
]}

Gammie, C. ^{[3
,4
]}

Dexter, J. ^{[5
,6
]}

Markoff, S. ^{[7
]}

Haggard, D. ^{[8
]}

Nayakshin, S. ^{[9
]}

Wang, Q. D. ^{[10
]}

Grosso, N. ^{[11
]}

Porquet, D. ^{[11
]}

Tomsick, J. A. ^{[12
]}

Degenaar, N. ^{[13
]}

Fragile, P. C. ^{[14
]}

Houck, J. C. ^{[2
]}

Wijnands, R. ^{[7
]}

Miller, J. M. ^{[13
]}

Baganoff, F. K. ^{[2
]}

机构：

[1] Boston Univ, Dept Astron, Boston, MA 02215 USA

[2] MIT Kavli Inst Astrophys & Space Res, Cambridge, MA 02139 USA

[3] Univ Illinois, Dept Astron, Urbana, IL 61801 USA

[4] Univ Illinois, Dept Phys, Urbana, IL 61801 USA

[5] Univ Calif Berkeley, Theoret Astrophys Ctr, Berkeley, CA 94720 USA

[6] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

[7] Univ Amsterdam, Astron Inst, Anton Pannekoek, NL-1090 GE Amsterdam, Netherlands

[8] Northwestern Univ, Dept Phys & Astron, Ctr Interdisciplinary Explorat & Res Astrophys, Evanston, IL 60208 USA

[9] Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England

[10] Univ Massachusetts, Dept Astron, Amherst, MA 01002 USA

[11] Univ Strasbourg, CNRS, UMR 7550, Observ Astronom Strasbourg, F-67000 Strasbourg, France

[12] Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA

[13] Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA

[14] Coll Charleston, Dept Phys & Astron, Charleston, SC 29424 USA

来源：

ASTROPHYSICAL JOURNAL | 2013年 / 774卷 / 01期

关键词：

accretion; accretion disks; black hole physics; radiation mechanisms: non-thermal; SUPERMASSIVE BLACK-HOLE; SOFT GAMMA-RAY; SAGITTARIUS-A; GALACTIC-CENTER; FUNDAMENTAL PLANE; XMM-NEWTON; FREQUENCY-DISTRIBUTIONS; GRMHD SIMULATIONS; MOLECULAR CLOUDS; FLARE STATISTICS;

D O I：

10.1088/0004-637X/774/1/42

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

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 similar to 10(34) erg s(-1) to 2 x 10(35) 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(-0.4)(+0.3); 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.

引用

页数：14

共 101 条

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