VERITAS Discovery of VHE Emission from RGB J2056+496
ATel #9721; Reshmi Mukherjee (Barnard College) for the VERITAS Collaboration
on 6 Nov 2016; 20:55 UT
Credential Certification: Reshmi Mukherjee (muk@astro.columbia.edu)
Subjects: Gamma Ray, >GeV, TeV, VHE, AGN, Blazar
We report the first detection of VHE emission from RGB J2056+496. This blazar, of unknown redshift, was targeted by VERITAS due to its favorable properties above 50 GeV, as described in the Fermi-LAT 2FHL catalog (M. Ackermann, et al., ApJS, Vol. 222, No. 1 (2016). The blazar is also an XMM-Newton source and a Swift-BAT source. It was observed for 4.2 h of good-quality live time between October 10, 2016 and November 6, 2016. A preliminary analysis of these observations yields an excess of 70 events above the background at the position of the blazar, corresponding to a statistical significance of 5.2
standard deviations. We interpret this excess as the discovery of VHE gamma-ray emission from the blazar. The corresponding flux observed above 200 GeV is (9.4 +/- 2.2) x10^-12 cm^-2 s^-1, or 4.0% of the Crab Nebula flux above the same threshold. We note that the blazar is 13 arc-seconds distant from the micro-quasar candidate LS III +49 13, and the two objects are effectively co-located for VERITAS.
VERITAS will continue to observe RGB J2056+496 and multi-wavelength observations are encouraged. Questions regarding the VERITAS observations should be directed to Reshmi Mukherjee (muk@astro.columbia.edu). Contemporaneous target-of-opportunity observations with the Swift satellite have also been scheduled. VERITAS (Very Energetic Radiation Imaging Telescope Array System) is located at the Fred Lawrence Whipple Observatory in southern Arizona, USA, and is most sensitive to gamma rays between ~85 GeV and ~30 TeV (http://veritas.sao.arizona.edu).
