Journal article
HESS J1943+213: An Extreme Blazar Shining through the Galactic Plane
The Astrophysical journal, Vol.862(1), p.41
07/20/2018
DOI: 10.3847/1538-4357/aacbd0
Abstract
HESS J1943+213 is a very high energy (VHE; >100 GeV) γ-ray source in the direction of the Galactic plane. Studies exploring the classification of the source are converging toward its identification as an extreme synchrotron BL Lac object. Here we present 38 hr of VERITAS observations of HESS J1943+213 taken over 2 yr. The source is detected with a significance of ∼20 standard deviations, showing a remarkably stable flux and spectrum in VHE γ-rays. Multifrequency Very Long Baseline Array (VLBA) observations of the source confirm the extended, jet-like structure previously found in the 1.6 GHz band with the European VLBI Network and detect this component in the 4.6 and 7.3 GHz bands. The radio spectral indices of the core and the jet and the level of polarization derived from the VLBA observations are in a range typical for blazars. Data from VERITAS, Fermi-LAT, Swift-XRT, the FLWO 48″ telescope, and archival infrared and hard X-ray observations are used to construct and model the spectral energy distribution (SED) of the source with a synchrotron self-Compton model. The well-measured γ-ray peak of the SED with VERITAS and Fermi-LAT provides constraining upper limits on the source redshift. Possible contribution of secondary γ-rays from ultra-high-energy cosmic-ray-initiated electromagnetic cascades to the γ-ray emission is explored, finding that only a segment of the VHE spectrum can be accommodated with this process. A variability search is performed across X-ray and γ-ray bands. No statistically significant flux or spectral variability is detected.
Details
- Title: Subtitle
- HESS J1943+213: An Extreme Blazar Shining through the Galactic Plane
- Creators
- A Archer - Washington University in St. LouisW Benbow - Harvard UniversityR Bird - University of California, Los AngelesR Brose - University of PotsdamM Buchovecky - University of California, Los AngelesV Bugaev - Washington University in St. LouisW Cui - Purdue University West LafayetteM. K Daniel - Harvard UniversityA Falcone - Pennsylvania State UniversityQ Feng - McGill UniversityJ. P Finley - Purdue University West LafayetteA Flinders - University of UtahL Fortson - University of MinnesotaA Furniss - California State University, East BayG. H Gillanders - Ollscoil na Gaillimhe – University of GalwayM Hütten - DESY, Platanenallee 6, D-15738 Zeuthen, GermanyD Hanna - McGill UniversityO Hervet - University of California, Santa CruzJ Holder - University of DelawareG Hughes - Harvard UniversityT. B Humensky - Columbia UniversityC. A Johnson - University of California, Santa CruzP Kaaret - University of IowaP Kar - University of UtahN Kelley-Hoskins - DESY, Platanenallee 6, D-15738 Zeuthen, GermanyD Kieda - University of UtahM Krause - DESY, Platanenallee 6, D-15738 Zeuthen, GermanyF Krennrich - Iowa State UniversityS Kumar - University of DelawareM. J Lang - Ollscoil na Gaillimhe – University of GalwayT. T. Y Lin - McGill UniversityS McArthur - Purdue University West LafayetteP Moriarty - Ollscoil na Gaillimhe – University of GalwayR Mukherjee - Columbia UniversityD Nieto - Columbia UniversityS O'Brien - University College DublinR. A Ong - University of California, Los AngelesA. N Otte - Georgia Institute of TechnologyN Park - University of ChicagoA Petrashyk - Columbia UniversityM Pohl - University of PotsdamA Popkow - University of California, Los AngelesE Pueschel - DESY, Platanenallee 6, D-15738 Zeuthen, GermanyJ Quinn - University College DublinK Ragan - McGill UniversityP. T Reynolds - Cork Institute of TechnologyG. T Richards - Georgia Institute of TechnologyE Roache - Harvard UniversityC Rulten - University of MinnesotaI Sadeh - DESY, Platanenallee 6, D-15738 Zeuthen, GermanyG. H Sembroski - Purdue University West LafayetteK Shahinyan - University of MinnesotaJ Tyler - McGill UniversityS. P Wakely - University of ChicagoO. M Weiner - Columbia UniversityA Weinstein - Iowa State UniversityR. M Wells - Iowa State UniversityP Wilcox - University of IowaA Wilhelm - University of PotsdamD. A Williams - University of California, Santa CruzW. F BriskenP Pontrelli - University of California, Santa CruzVERITAS Collaboration
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.862(1), p.41
- DOI
- 10.3847/1538-4357/aacbd0
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Publisher
- Institute of Physics (IOP)
- Number of pages
- 15
- Language
- English
- Date published
- 07/20/2018
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984200027202771
Metrics
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