SETI public: A Candidate Neutron Star Associated with Galactic Center Supernova Remnant Sagittarius A East

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Paper: astro-ph/0506168
Date: Wed, 8 Jun 2005 13:45:44 GMT (757kb)

Title: A Candidate Neutron Star Associated with Galactic Center Supernova
  Remnant Sagittarius A East

Authors: Sangwook Park (Penn State), Michael P. Muno (UCLA), Frederick K.
  Baganoff (MIT), Yoshitomo Maeda (ISAS), Mark Morris (UCLA), George Chartas
  (Penn State), Divas Sanwal (Penn State), David N. Burrows (Penn State),
and
  Gordon P. Garmire (Penn State)
Comments: ApJ preprint style 28 pages, 1 color fig (fig1), Accepted by ApJ
\\
  We present imaging and spectral studies of the supernova remnant (SNR)
Sagittarius (Sgr) A East from deep observations with the {\it Chandra X-Ray
Observatory}. The spatially-resolved spectral analysis of Sgr A East reveals
the presence of a two-temperature thermal plasma ($kT$ $\sim$ 1 keV and 5
keV)
near the center of the SNR. The central region is dominated by emission from
highly-ionized Fe-rich ejecta. We estimate a conservative upper limit on the
total Fe ejecta mass of the SNR, M$_{Fe}$ $<$ 0.27 M$_{\odot}$. Comparisons
with standard SN nucleosynthesis models suggest that this Fe mass limit is
consistent with a Type II SN explosion for the origin of Sgr A East. On the
other hand, the soft X-ray emission extending toward the north of the SNR
can
be described by a single-temperature ($kT$ $\sim$ 1.3 keV) thermal plasma
with
normal chemical composition. This portion of the SNR is thus X-ray emission
from the heated interstellar medium rather than the metal-rich stellar
ejecta.
We point out that a hard pointlike source CXOGC J174545.5$-$285829 (the
so-called ``cannonball'') at the northern edge of the SNR shows unusual
X-ray
characteristics among other Galactic center sources. The morphological,
spectral, and temporal characteristics of this source suggest an
identification
as a high-velocity neutron star. Based on the suggested Type II origin for
the
SNR Sgr A East and the proximity between the two, we propose that CXOGC
J174545.5$-$285829 is a high-velocity neutron star candidate, born from the
core-collapse SN which also created the SNR Sgr A East.

\\ ( http://arXiv.org/abs/astro-ph/0506168 , 757kb)

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