AAS 201st Meeting, January, 2003
Session 11. Seyfert Galaxies and AGNs
Poster, Monday, January 6, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[11.18] The Blazar Content of the Northern Gamma-Ray Sky

D. Sowards-Emmerd, R. W. Romani, P. F. Michelson (Stanford University)

Using survey data, we have evaluated the correlation of flat-spectrum radio sources with EGRET blazars in the Northern sky. A likelihood analysis incorporating the radio and X-ray properties and the Gamma-ray source localization is used to gauge the reliability of associations and to search for counterparts of previously unidentified EGRET sources. Above |b|=10 the survey is complete, where we find that 70% of the Northern EGRET sources have counterparts similar to the bright EGRET blazars. For several of these we identify known Blazars counterparts more likely than earlier proposed 3EG association; for ~20 of these we have new identifications. Spectroscopic confirmation of these candidates is in progress and we have found flat-spectrum radio quasars and BL Lac counterparts with redshifts as high as 4. We also find strong evidence for a set of 25 objects with NO possible counterpart like the known EGRET Blazars. These thus represent either a new extragalactic population or a population of Galactic objects (such as spin powered pulsars) with a large scale height. The survey has been extended into the plane, where we again, find several new blazar candidates; the bulk of the sources are, however, Galactic.

Looking ahead to the GLAST era we predict that several of the present 3EG sources are composite and that higher resolution data will break these into multiple Blazar IDs. Our survey is also identifying AGN outside of the EGRET error ellipses that will be counterparts for some of the 2000-3000 fainter blazars expected with GLAST.

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