HESS J1943+213 is a very high energy (VHE; >100 GeV) γ-ray source in the direction of the Galactic plane. 38 hours of deep VERITAS observations taken over two seasons detect the source with ∼20 σ significance. Monitoring observations of HESS J1943+213 show a remarkably stable flux and spectrum in VHE γ-rays. Studies exploring the classification of HESS J1943+213 are converging towards accepting the source as an extreme synchrotron BL Lac object. Specifically, overall SED characteristics of the source, the detection of a potential host galaxy in near-IR imaging, and VLBI observations of the HESS J1943+213 radio counterpart showing extended jet-like emission at milliarcsecond scale and core flux density variability establish the source as a blazar. Recent Very Long Baseline Array (VLBA) observations of the source (shown here for the first time) confirm the extended structure found in the 1.6 GHz band and detect the jet-like component in the 4.6 GHz and the 7.3 GHz bands. The spectral indices of the core and the jet-like components derived from the VLBA observations are in a range typical for blazars. HESS J1943+213 fits the extreme HBL description; however, with variability detected only at milliarcseconds scales in radio, it appears to be an abnormally stable VHE γ-ray blazar.
|Original language||English (US)|
|Title of host publication||High Energy Gamma-Ray Astronomy|
|Subtitle of host publication||6th International Meeting on High Energy Gamma-Ray Astronomy|
|Editors||Felix A. Aharonian, Felix A. Aharonian, Frank M. Rieger, Werner Hofmann|
|Publisher||American Institute of Physics Inc.|
|State||Published - Jan 4 2017|
|Event||6th International Symposium on High Energy Gamma-Ray Astronomy - Heidelberg, Germany|
Duration: Jul 11 2016 → Jul 15 2016
|Name||AIP Conference Proceedings|
|Other||6th International Symposium on High Energy Gamma-Ray Astronomy|
|Period||7/11/16 → 7/15/16|
Bibliographical notePublisher Copyright:
© 2017 Author(s).