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From: Dan Marrone  dmarrone@oddjob.uchicago.edu 
To: gcnews@aoc.nrao.edu
Subject: submit sgra-flare.tex ApJ, submitted

%astro-ph/0712.2877
\documentclass[preprint,12pt]{aastex}

\begin{document}

\title{An X-ray, IR, and Submillimeter Flare of Sagittarius A*}
\author{D.~P. Marrone\altaffilmark{1,2},
F.~K. Baganoff\altaffilmark{3}, M. Morris\altaffilmark{4},
J.~M. Moran\altaffilmark{5}, A.~M. Ghez\altaffilmark{4,6},
S.~D. Hornstein\altaffilmark{7}, C.~D. Dowell\altaffilmark{8},
D.~J. Mu\~{n}oz\altaffilmark{5}, M.~W. Bautz\altaffilmark{3},
G.~R. Ricker\altaffilmark{3}, W.~N. Brandt\altaffilmark{9},
G.~P. Garmire\altaffilmark{9}, J.~R. Lu\altaffilmark{4},
K. Matthews\altaffilmark{10}, J.-H. Zhao\altaffilmark{5},
R. Rao\altaffilmark{11}, and G. C. Bower\altaffilmark{12}}
\altaffiltext{1}{Jansky Postdoctoral Fellow, National Radio Astronomy
Observatory}
\altaffiltext{2}{Kavli Institute for Cosmological Physics, University
of Chicago, 5640 South Ellis Avenue, Chicago, IL, 60637, {\it
dmarrone@uchicago.edu}}
\altaffiltext{3}{Kavli Institute for Astrophysics and Space Research,
Massachusetts Institute of Technology, Cambridge, MA 02139-4307}
\altaffiltext{4}{Department of Physics and Astronomy, University of
California, Los Angeles, CA 90095-1547}
\altaffiltext{5}{Harvard-Smithsonian Center for Astrophysics,
60 Garden Street, Cambridge, MA 02138}
\altaffiltext{6}{Institute for Geophysics and Planetary Physics,
University of California, Los Angeles, CA 90095-1565}
\altaffiltext{7}{Center for Astrophysics and Space Astronomy,
Department of Astrophysical and Planetary Sciences, University of
Colorado, Boulder, CO 80309}
\altaffiltext{8}{Department of Physics, California Institute of
Technology, Pasadena, CA 91125}
\altaffiltext{9}{Department of Astronomy and Astrophysics,
Pennsylvania State University, University Park, PA 16802-6305}
\altaffiltext{10}{Caltech Optical Observatories, California Institute
of Technology, MS 320-47, Pasadena, CA 91125}
\altaffiltext{11}{Institute of Astronomy and Astrophysics, Academia
Sinica, P.O. Box 23-141, Taipei 10617, Taiwan}
\altaffiltext{12}{Department of Astronomy and Radio Astronomy
Laboratory, University of California at Berkeley, Campbell Hall,
Berkeley, CA 94720}

\begin{abstract}
Energetic flares are observed in the Galactic supermassive black hole
Sagittarius A* from radio to X-ray wavelengths. On a few occasions,
simultaneous flares have been detected in IR and X-ray observations,
but clear counterparts at longer wavelengths have not been seen. We
present a flare observed over several hours on July 17, 2006 with the
Chandra X-ray Observatory, the Keck II telescope, the Caltech
Submillimeter Observatory, and the Submillimeter Array. All telescopes
observed strong flare events, but the submillimeter peak is found to
occur nearly 100 minutes after the X-ray peak. Submillimeter
polarization data show a polarization signature in the excess flare
emission, increasing from 9\% to 17\% fractional polarization as the
flare passes through its peak, consistent with a transition from
optically thick to thin synchrotron emission. The temporal and
spectral behavior of the flare requires that the energetic electrons
responsible for the emission cool faster than expected from their
radiative output. This is consistent with adiabatic cooling in an
expanding emission region, with X-rays produced through self-Compton
scattering. We also present the submillimeter detection of an IR flare
on July 31, 2005, which showed a larger peak IR flux and similar
submillimeter flux but did not have measurable X-ray emission. This
flare also shows a delay between the IR peak and submillimeter peak,
although it is significantly shorter. The submillimeter lag and the
variable ratio of IR and X-ray luminosities are related through a
synchrotron and self-Compton model.
\end{abstract}


\end{document}