The 3 Ms Chandra campaign on Sgr A*: a census of X-ray flaring activity from the Galactic center

Abstract Over the last decade, X-ray observations of Sgr A* have revealed a black hole in a deep sleep, punctuated roughly once per day by brief flares. The extreme X-ray faintness of this supermassive black hole has been a long-standing puzzle in black hole accretion. To study the accretion processes in the Galactic center, Chandra (in concert with numerous ground- and space-based observatories) undertook a 3 Ms campaign on Sgr A* in 2012. With its excellent observing cadence, sensitivity, and spectral resolution, this Chandra X-ray Visionary Project (XVP) provides an unprecedented opportunity to study the behavior of the closest supermassive black hole. We present a progress report from our ongoing study of X-ray flares, including the brightest flare ever seen from Sgr A*. Focusing on the statistics of the flares and the quiescent emission, we discuss the physical implications of X-ray variability in the Galactic center.

[1]  J. Cuadra,et al.  Dissecting X-ray–Emitting Gas Around the Center of Our Galaxy , 2013, Science.

[2]  S. Nayakshin,et al.  A CHANDRA/HETGS CENSUS OF X-RAY VARIABILITY FROM Sgr A* DURING 2012 , 2013, 1307.5843.

[3]  N. Gehrels,et al.  THE X-RAY FLARING PROPERTIES OF Sgr A* DURING SIX YEARS OF MONITORING WITH SWIFT , 2012, 1210.7237.

[4]  C. Lawrence,et al.  AAS/High Energy Astrophysics Division , 2013 .

[5]  H. Falcke,et al.  CHANDRA/HETGS OBSERVATIONS OF THE BRIGHTEST FLARE SEEN FROM Sgr A* , 2012, 1209.6354.

[6]  R. Lenzen,et al.  SOURCE-INTRINSIC NEAR-INFRARED PROPERTIES OF SGR A*: TOTAL INTENSITY MEASUREMENTS , 2012, 1208.5836.

[7]  N. Crosby.  Frequency distributions: from the sun to the earth , 2011 .

[8]  S. Anderson,et al.  Using the Fundamental Plane of black hole activity to distinguish X-ray processes from weakly accreting black holes , 2011, 1105.3211.

[9]  A. Goldwurm,et al.  THE TWO STATES OF Sgr A* IN THE NEAR-INFRARED: BRIGHT EPISODIC FLARES ON TOP OF LOW-LEVEL CONTINUOUS VARIABILITY , 2010, 1008.1984.

[10]  R. Genzel,et al.  The galactic center massive black hole and nuclear star cluster , 2010, 1006.0064.

[11]  S. Markoff.  Revelations in our own backyard: Chandra’s unique Galactic Center discoveries , 2010, Proceedings of the National Academy of Sciences.

[12]  F. Baganoff,et al.  INFLOW–OUTFLOW MODEL WITH CONDUCTION AND SELF-CONSISTENT FEEDING FOR Sgr A* , 2010, 1004.0702.

[13]  T. Paumard,et al.  EVIDENCE FOR X-RAY SYNCHROTRON EMISSION FROM SIMULTANEOUS MID-INFRARED TO X-RAY OBSERVATIONS OF A STRONG Sgr A* FLARE , 2009, 0903.3416.

[14]  J. M. Moran,et al.  An X-Ray, Infrared, and Submillimeter Flare of Sagittarius A* , 2007, 0712.2877.

[15]  H. Marshall,et al.  High-Resolution X-Ray Spectroscopy of a Low-Luminosity Active Galactic Nucleus: The Structure and Dynamics of M81* , 2007 .

[16]  R. Narayan,et al.  Thermal X-Ray Iron Line Emission from the Galactic Center Black Hole Sagittarius A* , 2005, astro-ph/0511590.

[17]  Sera Markoff,et al.  Sagittarius A* in Context: Daily Flares as a Probe of the Fundamental X-Ray Emission Process in Accreting Black Holes , 2004, astro-ph/0412140.

[18]  H. Falcke,et al.  A scheme to unify low-power accreting black holes Jet-dominated accretion flows and the radio/X-ray correlation , 2003, astro-ph/0305335.

[19]  T. D. Matteo,et al.  A Fundamental plane of black hole activity , 2003, astro-ph/0305261.

[20]  Caltech,et al.  Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre , 2001, Nature.

[21]  Peter L. Biermann,et al.  The Nature of the 10 kilosecond X-ray flare in Sgr A* , 2001 .

[22]  UCLA,et al.  Chandra X-Ray Spectroscopic Imaging of Sagittarius A* and the Central Parsec of the Galaxy , 2001, astro-ph/0102151.