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| Paper: |
X-ray Echoes of Infrared Flaring in Sgr A* |
| Volume: |
439, The Galactic Center: a Window to the Nuclear Environment of Disk Galaxies |
| Page: |
450 |
| Authors: |
Wardle, M. |
| Abstract: |
Sgr A* exhibits flaring in the infrared several times each day,
occasionally accompanied by flaring in X-rays. The infrared flares
are believed to arise through synchrotron emission from a transient
population of accelerated electrons. The X-ray flaring has been
interpreted as self-synchrotron-compton, inverse compton, or
synchrotron emission associated with the transient electrons.
Here I consider the upscattering of infrared flare photons by
relativistic thermal electrons in the accretion flow around Sgr A*.
Typical profiles of electron density and temperature in the accretion
flow are adopted and the X-ray light curves produced by upscattering
of infrared flare photons by the accretion flow are computed.
Peak X-ray luminosities between 1033 and 1034 erg s-1
are attained for a 10 mJy near-infrared flare, compatible with
observed coincident infrared/X-ray flares from Sgr A*. Even if this process
is not responsible for the observed flares it still presents a serious
constraint on accretion flow models, which must avoid over-producing
X-rays and also predicting observable time lags between flaring in infrared
and in X-rays.
Future high-resolution infrared instrumentation will be able to place the
location of the infrared flare and in coordination with the X-ray
would severely constrain the disc geometry and the radial profiles of
electron density and temperature in the accretion flow. |
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