Paper: astro-ph/0506242
Date: Fri, 10 Jun 2005 18:22:49 GMT (193kb)

Title: The Sgr B2 X-ray Echo of the Galactic Center Supernova Explosion that
Produced Sgr A East

Authors: C. L. Fryer, G. Rockefeller, A. Hungerford, F. Melia
Comments: 27 pages (including 9 figures), submitted to ApJ, for hi-res/color
figures, see http://qso.lanl.gov/~clf
Report-no: LA-UR-05-4218
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The possible impact Sgr A East is having on the Galactic center has fueled
speculation concerning its age and the energetics of the supernova explosion
that produced it. We have carried out the first in-depth analysis of the
remnant's evolution and its various interactions: with the stellar winds
flowing out from the inner ~2 pc, with the supermassive black hole, Sgr A*, and
with the 50 km/s molecular cloud behind and to the East of the nucleus. We have
found that a rather "standard" supernova explosion with energy ~1.5e51 ergs is
sufficient to create the remnant we see today, and that the latter is probably
only ~1,700 years old. The X-ray Ridge between ~9" and 15" to the NE of Sgr A*
appears to be the product of the current interaction between the remaining
supernova ejecta and the outflowing winds. Perhaps surprisingly, we have also
found that the passage of the remnant across the black hole would have enhanced
the accretion rate onto the central object by less than a factor 2. Such a
small increase cannot explain the current Fe fluorescence observed from the
molecular cloud Sgr B2; this fluorescence would have required an increase in
Sgr A*'s luminosity by 6 orders of magnitude several hundred years ago.
Instead, we have uncovered what appears to be a more plausible scenario for
this transient irradiation--the interaction between the expanding remnant and
the 50 km/s molecular cloud. The first impact would have occurred about 1,200
years after the explosion, producing a 2-200 keV luminosity of ~1e39 ergs/s.
During the intervening 300-400 years, the dissipation of kinetic energy
subsided considerably, leading to the much lower luminosity (~1e36 ergs/s at
2-10 keV) we see today.

\\ ( http://arXiv.org/abs/astro-ph/0506242 , 193kb)

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Paper: astro-ph/0506244
Date: Fri, 10 Jun 2005 19:33:16 GMT (489kb)

Title: The X-ray Ridge Surrounding Sgr A* at the Galactic Center

Authors: Gabriel Rockefeller, Christopher L. Fryer, Frederick K. Baganoff, and
Fulvio Melia
Comments: 10 pages, 3 figures, submitted to ApJL
Report-no: LA-UR-05-3459
\\
We present the first detailed simulation of the interaction between the
supernova explosion that produced Sgr A East and the wind-swept inner ~ 2-pc
region at the Galactic center. The passage of the supernova ejecta through this
medium produces an X-ray ridge ~ 9'' to 15'' to the NE of the supermassive
black hole Sagittarius A* (Sgr A*). We show that the morphology and X-ray
intensity of this feature match very well with recently obtained Chandra
images, and we infer a supernova remnant age of less than 2,000 years. This
young age--a factor 3--4 lower than previous estimates--arises from our
inclusion of stellar wind effects in the initial (pre-explosion) conditions in
the medium. The supernova does not clear out the central ~ 0.2-pc region around
Sgr~A* and does not significantly alter the accretion rate onto the central
black hole upon passage through the Galactic center.

\\ ( http://arXiv.org/abs/astro-ph/0506244 , 489kb)