A revised catalogue of EGRET sources

by Jean-Marc Casandjian and Isabelle Grenier


accepted for publication in A&A

Aim: we present a catalog of point γ-ray sources detected by the EGRET detector aboard the Compton Gamma Ray Observatory. We have used the whole γ-ray dataset of reprocessed photons at energies above 100 MeV together with new Galactic interstellar emission models based on recent CO, HI, dark gas, and interstellar radiation field data. Two different assumptions have been used for the cosmic-ray distribution in the Galaxy to explore the resulting systematic uncertainties in source detection and characterization.

Method: we have used the same 2-dimensional maximum-likelihood detection method as for the 3rd EGRET catalogue.

Results: the revised catalogue lists 188 sources, 14 of which are marked as confused, compared to the 271 entries of the 3rd EGRET (3EG) catalogue. 107 former sources have not been confirmed because of the additional structure in the interstellar background. The vast majority of them were unidentified and marked as possibly extended or confused in the 3EG catalogue. In particular, we do not confirm most of the 3EG sources associated with the local clouds of the Gould Belt. Alternatively, we find 30 new sources with no 3EG counterpart. The new error circles for the confirmed 3EG sources largely overlap the previous ones, but several counterparts of particular interest that had been discussed in the litterature, such as Sgr A*, radiogalaxies and several microquasars are now found outside the error circles. We have cross-correlated the source positions with a large number of radio pulsars, pulsar wind nebulae, supernova remnants, OB associations, blazars and flat radiosources and we find a surprising large number of sources (87) at all latitudes with no counterpart among the potential γ-ray emitters.

The counterparts found in the error boxes are colour coded in the next image:

known objects in yellow (the Sun, the Large Magellanic cloud, the LSI +61 303 X-ray binary) and in red (the Vela, Crab, and Geminga pulsars as well as PSR J1709-4429, PSR J1057-5226, and possibly PSR J1048-5832), other ATNF pulsars in pink, supernova remnants from the Green catalogue in cyan, ASDC and CGRaBS blazar candidates in blue, other flat-spectrum radio sources from CRATES in purple.

click on the links to download

the catalogue in ascii format:    EGR_catalogue.txt

the article in pdf:                       EGR_article.pdf