On the nature of the discrete gamma-ray sources in the vicinity of the supernova remnant G312.4-0.4

Citation
G. Case et D. Bhattacharya, On the nature of the discrete gamma-ray sources in the vicinity of the supernova remnant G312.4-0.4, ASTROPHYS J, 521(1), 1999, pp. 246-254
Citations number
40
Categorie Soggetti
Space Sciences
Journal title
ASTROPHYSICAL JOURNAL
ISSN journal
0004637X → ACNP
Volume
521
Issue
1
Year of publication
1999
Part
1
Pages
246 - 254
Database
ISI
SICI code
0004-637X(19990810)521:1<246:OTNOTD>2.0.ZU;2-K
Abstract
We discuss the excess gamma-ray emission seen from point sources in the vic inity of the supernova remnant (SNR) G312.4-0.4 with the EGRET instrument o n board the Compton Gamma Ray Observatory in the energy range of 100 MeV to 10 GeV. Two gamma-ray sources have been significantly detected. The best-f it position for the source 2EG J1412-6211, which was originally discovered by COS B (catalog name 2CG 311-01), is located approximately 17' southwest of the center of the supernova remnant G312.4-0.4. We find the gamma-ray fl ux level of this source to be relatively constant over a period of 4 yr. Th e origin of the gamma-ray emission with respect to a SNR-pulsar source is d iscussed. The best-fit position for the other source, 2EGS J1418-6049, lies 1.degrees 3 northeast of the center of G312.4-0.4 It has a variable flux l evel, with a spectrum extending up to a few GeV. We argue that 2EGS J1418-6 049 is transient in nature and that its variability makes it unlikely to be associated. with G312.4-0.4 or any other SNR or isolated pulsar. We sugges t that this source may belong to a new class of unidentified Galactic sourc es which includes the EGRET source 2EG J0241 + 6119 (2CG 135+01).