Fermi Gamma-ray Space Telescope

Enhancing the value of Fermi LAT catalogs with dedicated radio counterpart searches

Frank Schinzel
(G.B. Taylor, L. Petrov on behalf of the Fermi-LAT collaboration)


Understanding the nature of Fermi gamma-ray sources largely relies upon identifications at other wavebands. Besides Active Galactic Nuclei (AGN), the second largest group among detected gamma-ray sources are objects that have no known electromagnetic counterpart and are called "unassociated". The physical origin of these objects is unknown. In 2013, we started a radio survey of all unassociated objects to date. A new survey has been underway over the past year targeting over 1800 new unassociated objects found in the 8 year catalog, and also includes associations with poor astrometric localization. Observational evidence establishing the connection between known radio-loud AGN and the gamma-ray sky led us to develop a statistical framework that allows to obtain reliable associations of radio-loud AGN with unassociated gamma-ray objects. With this we discovered over 200 new gamma-ray loud AGN and improved astrometric positions of radio counterparts to known gamma-ray objects. We also indirectly provide candidates for Pulsar counterpart searches and candidates for Galactic objects and searches for exotic objects. I will present a summary of our efforts and provide a status update on ongoing work in the context of the 8 year Fermi catalog.