A Statistical Approach to Recognizing Source Classes for Unassociated Sources in the First Fermi-LAT Catalog

TL;DR

This paper uses statistical analysis of gamma-ray properties to classify unassociated sources in the Fermi-LAT catalog as likely AGN or pulsar types, aiding future follow-up studies.

Contribution

It introduces a statistical method to classify unassociated gamma-ray sources in the 1FGL catalog, improving source identification accuracy.

Findings

Classified 221 AGN-like sources

Classified 134 pulsar-like sources

Achieved ~80% accuracy in source class predictions

Abstract

The Fermi Large Area Telescope First Source Catalog (1FGL) provided spatial, spectral, and temporal properties for a large number of gamma-ray sources using a uniform analysis method. After correlating with the most-complete catalogs of source types known to emit gamma rays, 630 of these sources are "unassociated" (i.e. have no obvious counterparts at other wavelengths). Here, we employ two statistical analyses of the primary gamma-ray characteristics for these unassociated sources in an effort to correlate their gamma-ray properties with the AGN and pulsar populations in 1FGL. Based on the correlation results, we classify 221 AGN-like and 134 pulsar-like sources in the 1FGL unassociated sources. The results of these source "classifications" appear to match the expected source distributions, especially at high Galactic latitudes. While useful for planning future multiwavelength follow-up observations, these analyses use limited inputs, and their predictions should not be considered equivalent to "probable source classes" for these sources. We discuss multiwavelength results and catalog cross-correlations to date, and provide new source associations for 229 Fermi-LAT sources that had no association listed in the 1FGL catalog. By validating the source classifications against these new associations, we find that the new association matches the predicted source class in ~80% of the sources.