VERITAS and VLBA observations of HESS J1943+213

Karlen Shahinyan

doi:10.1063/1.4968940

VERITAS and VLBA observations of HESS J1943+213

Karlen Shahinyan

Physics and Astronomy (Twin Cities)

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

2 Scopus citations

Abstract

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.
ISBN (Electronic)	9780735414563
DOIs	https://doi.org/10.1063/1.4968940
State	Published - Jan 4 2017
Event	6th International Symposium on High Energy Gamma-Ray Astronomy - Heidelberg, Germany Duration: Jul 11 2016 → Jul 15 2016

Publication series

Name	AIP Conference Proceedings
Volume	1792
ISSN (Print)	0094-243X
ISSN (Electronic)	1551-7616

Other

Other	6th International Symposium on High Energy Gamma-Ray Astronomy
Country/Territory	Germany
City	Heidelberg
Period	7/11/16 → 7/15/16

Bibliographical note

Publisher Copyright:
© 2017 Author(s).

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10.1063/1.4968940

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VERITAS and VLBA observations of HESS J1943+213. / Shahinyan, Karlen.
High Energy Gamma-Ray Astronomy: 6th International Meeting on High Energy Gamma-Ray Astronomy. ed. / Felix A. Aharonian; Felix A. Aharonian; Frank M. Rieger; Werner Hofmann. American Institute of Physics Inc., 2017. 040036 (AIP Conference Proceedings; Vol. 1792).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Shahinyan, K 2017, VERITAS and VLBA observations of HESS J1943+213. in FA Aharonian, FA Aharonian, FM Rieger & W Hofmann (eds), High Energy Gamma-Ray Astronomy: 6th International Meeting on High Energy Gamma-Ray Astronomy., 040036, AIP Conference Proceedings, vol. 1792, American Institute of Physics Inc., 6th International Symposium on High Energy Gamma-Ray Astronomy, Heidelberg, Germany, 7/11/16. https://doi.org/10.1063/1.4968940

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AB - 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.

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VERITAS and VLBA observations of HESS J1943+213

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