{
  "id": "1209.6354",
  "version": "v1",
  "published": "2012-09-27T19:59:59.000Z",
  "updated": "2012-09-27T19:59:59.000Z",
  "title": "Chandra-HETGS Observations of the Brightest Flare Seen from Sgr A*",
  "authors": [
    "M. A. Nowak",
    "J. Neilsen",
    "S. B. Markoff",
    "F. K. Baganoff",
    "D. Porquet",
    "N. Grosso",
    "Y. Levin",
    "J. Houck",
    "A. Eckart",
    "H. Falcke",
    "L. Ji",
    "J. M. Miller",
    "Q. D. Wang"
  ],
  "comment": "To be published in the Astrophysical Journal. Animated GIF of the flare image available at: www.sgra-star.com",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Starting in 2012, we began an unprecedented observational program focused on the supermassive black hole in the center of our Galaxy, Sgr A*, utilizing the High Energy Transmission Gratings Spectrometer (HETGS) instrument on the Chandra X-ray Observatory. These observations will allow us to measure the quiescent X-ray spectra of Sgr A* for the first time at both high spatial and spectral resolution. The X-ray emission of Sgr A*, however, is known to flare roughly daily by factors of a few to ten times over quiescent emission levels, with rarer flares extending to factors of greater than 100 times quiescence. Here were report an observation performed on 2012 February 9 wherein we detected what is the highest peak flux and fluence flare ever observed from Sgr A*. The flare, which lasted for 5.6 ks and had a decidedly asymmetric profile with a faster decline than rise, achieved a mean absorbed 2-8 keV flux of (8.5+/-0.9)X10^{-12} erg cm^{-2} s^{-1}. The peak flux was 2.5 times higher, and the total 2-10 keV emission of the event was approximately 10^{39} erg. Only one other flare of comparable magnitude, but shorter duration, has been observed in Sgr A* by XMM-Newton in 2002 October. We perform spectral fits of this Chandra observed flare, and compare our results to the two brightest flares ever observed with XMM-Newton. We find good agreement among the fitted spectral slopes (Gamma~2) and X-ray absorbing columns (N_H~15X10^{22} cm^{-2}) for all three of these events, resolving prior differences (which are most likely due to the combined effects of pileup and spectral modeling) among Chandra and XMM-Newton observations of Sgr A* flares. We also discuss fits to the quiescent spectra of Sgr A*.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2012-09-27T19:59:59.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "brightest flare",
      "chandra-hetgs observations",
      "high energy transmission gratings spectrometer",
      "peak flux",
      "quiescent x-ray spectra"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/0004-637X/759/2/95",
      "journal": "The Astrophysical Journal",
      "year": 2012,
      "month": "Nov",
      "volume": 759,
      "number": 2,
      "pages": 95
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1188272,
      "adsabs": "2012ApJ...759...95N"
    }
  }
}