Daily Image
11-07-2008
e-EVN detection of the candidate radio counterpart of a gamma-ray source
| Submitter: | Alfonso Trejo and Zsolt Paragi |
| Description: | On the 25th of June 2008 the e-EVN observed the candidate radio counterpart to a mysterious variable gamma-ray source detected by AGILE in the Cygnus region. The origin of many of these variable gamma-ray sources is unknown. Finding counterparts at other wavelengths may help to reveal their nature. It was proposed that the recently detected variable gamma-ray source in Cygnus might be in fact related to 3EG J2020+4017, a long-time unidentified object first discovered by the EGRET satellite. There is only one hard X-ray source known in the region, for which accurate coordinates were measured by INTEGRAL and especially SWIFT. This allowed a search in the radio regime and indeed a source was detected by the VLA, in positional agreement with the X-ray source and an IR object known as 2MASX J20183871+4041003. All this multi-wavelength information supports the idea of an obscured accreting object for 3EG J2020+4017, likely an AGN at z<0.1, but X-ray binary nature is still a possibility. Both of these interpretations require that the radio source is compact on milliarcsecond scales. Indeed a compact, partially resolved source is detected in the e-EVN observations, which provide superior resolution compared to the other instruments. The figure shows the optical image with a prominent supernova remnant in the middle. The circles show 95% confidence levels in position for the gamma- and X--ray detections, the + indicates the IR/VLA position, and the inset shows the e-EVN image. Further observations in all wavelengths are required to fully establish or reject the relationship of these sources. For more details about the e-EVN observations see the Astronomer's Telegram #1597. Large scale colour figure courtesy of Gloria Dubner. |
| Copyright: | JIVE |
| Tweet |  |