HEAD Division Meeting 1999, April 1999
Session 21. Other
Poster, Tuesday, April 13, 1999, 8:30am-6:02pm, Gold Room

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[21.02] Radio Fields Around Unidentified EGRET Sources

J.A. Combi, G.E. Romero, P. Benaglia, I.N. Azc\'{a}rate (Instituto Argentino de Radioastronom\'{\i}a)

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\circ, and 40 at \mid b \mid < 10\circ.

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± 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.

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