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

J. Neilsen, , A. Nowak, M. (1) , C. Gammie, , J. Dexter, , S. Markoff, , D. Haggard, , S. Nayakshin, , D. Wang, Q. , N. Grosso, (2) , D. Porquet, (2) , A. Tomsick, J. , N. Degenaar, , C. Fragile, P. , C. Houck, J. , R. Wijnands, , M. Miller, J. , K. Baganoff, F.

1 MIT Kavli Institute for Astrophysics and Space Research
2 ObAS - Observatoire astronomique de Strasbourg

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.

Mots clés: accretion; accretion disks; black hole physics; radiation mechanisms: nonthermal

Domaines: Planète et Univers [physics]; Astrophysique [astro-ph]; Astrophysique galactique [astro-ph.GA]; Phénomènes cosmiques de haute energie [astro-ph.HE]

J. Neilsen,, A. Nowak, M., C. Gammie,, J. Dexter,, S. Markoff,, et al.. The 3 Ms Chandra campaign on Sgr A*: a census of X-ray flaring activity from the Galactic center. Proceedings of the International Astronomical Union, 2013, 9 (S303), pp.374-378. ⟨10.1017/S1743921314000945⟩. ⟨hal-02327542⟩