A LEPTONIC MODEL OF STEADY HIGH-ENERGY GAMMA-RAY EMISSION FROM Sgr A

Recent observations of Sgr A* by Fermi and HEss have detected steady gamma -ray emission in the GeV and TeV bands. We present a new model to explain the GeV gamma -ray emission by inverse Compton scattering by nonthermal electrons supplied by the NIR/X-ray flares of Sgr A*. The escaping electrons fr...

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Bibliographic Details
Published in:The Astrophysical journal 2012-03, Vol.748 (1), p.1-5
Main Authors: KUSUNOSE, Masaaki, TAKAHARA, Fumio
Format: Article
Language:English
Subjects:
Astronomy
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
BLACK HOLES
COMPTON EFFECT
COSMIC ELECTRONS
DUSTS
Earth, ocean, space
Elastic scattering
Emission
ENERGY DENSITY
Exact sciences and technology
Fittings
Flares
GALAXIES
GAMMA RADIATION
Inverse
MAGNETIC FIELDS
NEBULAE
PHOTON EMISSION
Photons
PLASMA
PULSARS
SPECTRA
STARS
TEV RANGE
ULTRAVIOLET RADIATION
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Summary:Recent observations of Sgr A* by Fermi and HEss have detected steady gamma -ray emission in the GeV and TeV bands. We present a new model to explain the GeV gamma -ray emission by inverse Compton scattering by nonthermal electrons supplied by the NIR/X-ray flares of Sgr A*. The escaping electrons from the flare regions accumulate in a region with a size of ~10 super(18) cm and magnetic fields of [< ~]10 super(-4) G. Those electrons produce gamma -rays by inverse Compton scattering off soft photons emitted by stars and dust around the central black hole. By fitting the GeV spectrum, we find constraints on the magnetic field and the energy density of optical-UV radiation in the central 1 pc region around the supermassive black hole. While the GeV spectrum is well fitted by our model, the TeV gamma -rays, whose spectral index is different from that of the GeV emission, may be from different sources such as pulsar wind nebulae.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637x/748/1/34