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Discovery Of New SNR Candidates in the Galactic Center Region with ASCA and Chandra
Author(s) -
Senda Atsushi,
Murakami Hiroshi,
Koyama Katsuji
Publication year - 2003
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200385029
Subject(s) - physics , astrophysics , galactic center , spectral line , line (geometry) , x ray , plasma , emission spectrum , center (category theory) , line width , astronomy , galaxy , optics , crystallography , chemistry , geometry , mathematics , quantum mechanics
We report the discovery of diffuse X‐ray features which are possible SNR candidates near the Galactic Center (GC) observed with ACSA and Chandra G0.570–0.018 has extremely small (20″ diameter) shell‐like morphology. Its X‐ray spectrum exhibits strong Fe‐K line emission and is well fitted by an NEI model with a temperature of about 6 keV. These characteristics suggest that G0.570–0.018 is a quite young ( t ∼ 100 year) SNR. Diffuse hard X‐rays were also detected from G359.92–0.09. Its X‐ray spectrum also exhibits strong Fe‐K line emission. The X‐ray excess coincides with the shell‐type feature observed in the radio continuum (e.g., Ho et al. 1985), which is attributable to a new SNR. In addition, we have discovered several soft X‐ray clumps. Their X‐ray spectra are thermal ( kT ∼ 1 keV) and clearly show atomic line features such as Si, S, Ar and Ca. The origin of the diffuse X‐ray emission from the GC region has been an unresolved issue for over a decade. Hard clumps such as G0.570–0.018 are likely to be young/middle‐aged SNRs, and could produce the hot component of the GC plasma, while relatively soft (∼1 keV) clumps, which also may be SNRs, could contribute to the cool component of the GC plasma.