208 research outputs found
Suzaku Observations of the Great Annihilator and the Surrounding Diffuse Emissions
We report the Suzaku observation of 1E 1740.7-2942, a black hole candidate
called the "Great Annihilator" (GA). The high-quality spectrum of Suzaku
provides the severest constraints on the parameters of the GA. Two clumpy
structures are found around the GA in the line images of FeI Kalpha at 6.4 keV
and SXV Kalpha at 2.45 keV. One clump named M359.23-0.04 exhibits the 6.4-keV
line with an equivalent width of ~ 1.2 keV, and is associated with a molecular
cloud in the radio CS(J=1-0) map. Thus the 6.4-keV line from M359.23-0.04 is
likely due to X-ray fluorescence irradiated by an external X-ray source. The
irradiating X-rays would be either the past flare of Sagittarius A* or the
bright nearby source, the GA. The other clump named G359.12-0.05 is associated
with the radio supernova remnant candidate G359.07-0.02. We therefore propose
that G359.12-0.05 is an X-ray counterpart of G359.07-0.02. G359.12-0.05 has a
thin thermal plasma spectrum with a temperature of kT ~ 0.9 keV. The plasma
parameters of G359.12-0.05 are consistent with those of a single supernova
remnant in the Galactic center region.Comment: 10 pages, 8 figures, accepted for publication in PASJ (Vol.62, No.4
Nearly Gorenstein local rings defined by maximal minors of a matrix
We investigate the nearly Gorenstein property of a local ring defined by the
maximal minors of a specific matrix with entries in the formal
power series ring over a field . Our findings
allow us to present numerous concrete examples, such as nearly Gorenstein rings
that are not almost Gorenstein and vice versa
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