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
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).