Radio detections towards unidentified variable EGRET sources
arXiv:0803.0721 · doi:10.1051/0004-6361:20078299
Abstract
Context. A considerable fraction of the gamma-ray sources discovered with the Energetic Gamma-Ray Experiment Telescope (EGRET) remain unidentified. The EGRET sources that have been properly identified are either pulsars or variable sources at both radio and gamma-ray wavelengths. Most of the variable sources are strong radio blazars.However, some low galactic-latitude EGRET sources, with highly variable gamma-ray emission, lack any evident counterpart according to the radio data available until now. Aims. The primary goal of this paper is to identify and characterise the potential radio counterparts of four highly variable gamma-ray sources in the galactic plane through mapping the radio surroundings of the EGRET confidence contours and determining the variable radio sources in the field whenever possible. Methods. We have carried out a radio exploration of the fields of the selected EGRET sources using the Giant Metrewave Radio Telescope (GMRT) interferometer at 21 cm wavelength, with pointings being separated by months. Results. We detected a total of 151 radio sources. Among them, we identified a few radio sources whose flux density has apparently changed on timescales of months. Despite the limitations of our search, their possible variability makes these objects a top-priority target for multiwavelength studies of the potential counterparts of highly variable, unidentified gamma-ray sources.
7 printed pages with 4 figures, 4 pages of online material with 1 figure. Accepted for publication in Astronomy and Astrophysics
References in corpus (17)
- Variable Very High Energy Gamma-ray Emission from the Microquasar LS I +61 303
- Discovery of very high energy gamma-rays associated with an X-ray binary
- Discovery of a High-Energy Gamma-Ray-Emitting Persistent Microquasar
- Hadronic gamma-ray emission from windy microquasars
- Variability of EGRET Gamma-Ray Sources
- A broadband leptonic model for gamma-ray emitting microquasars
- Accretion vs colliding wind models for the gamma-ray binary LS I +61 303: an assessment
- A variability analysis of low-latitude unidentified gamma-ray sources
- Precessing microblazars and unidentified gamma-ray sources
- Blazar Counterparts for 3EG Sources at -40 < decl. < 0: Pushing South Through the Bulge
- High-mass microquasars and low-latitude gamma-ray sources
- Leptonic secondary emission in a hadronic microquasar model
- Optical Properties of faint FIRST Variable Radio Sources
- Discovery of a new radio galaxy within the error box of the unidentified gamma-ray source 3EG J1735-1500
- On the time variability of gamma-ray sources: A numerical analysis of variability indices
- A microquasar model applied to unidentified gamma-ray sources
- Identifying variable gamma-ray sources through radio observations