The second EGRET catalog and its supplement (Thompson et al. 1995, 1996) contain 157 point sources detected at energies between 30 MeV and 20 GeV. Just about 40 % of these sources have been identified with objects also detected at lower energy bands, like pulsars and blazars. Of the unidentified sources, 56 are located at galactic latitudes mid b mid > 10(deg) , and 40 at mid b mid < 10(deg) . We present here the results of 1.42-GHz continuum and HI-line observations of the environs of the unidentified EGRET sources 2EG J0720-4746, 2EGS J0724-5157, and 2EG J1648-5042, obtained with single dish telescopes at IAR. From these observations we have found that the most likely radio counterparts of 2EG J0720-4746 and 2EG J1648-5042 are extragalactic sources, namely J0721-4744 and J1650-5044. On the other hand, a galactic origin seems feasible for 2EGS J0724-5157: it is supported by the detection of a nonthermal source positionally coincident with a minimum in the HI maps at a velocity of -3+/-2 km s(-1) . The possibility of a SNR interacting with a nearby cloud, in a similar case to that disclosed by Combi et al (1998), should be explored in the future. References: Combi J.A., et al. 1998, A&A 333, L91; Thompson D.J., et al. 1995, ApJS 101, 259; Thompson D.J., et al. 1996, ApJS 107, 227.
AAS/High Energy Astrophysics Division #4
- Pub Date:
- April 1999