A Decade of Multiwavelength Observations of the TeV Blazar 1ES 1215+303: Extreme Shift of the Synchrotron Peak Frequency and Long-term Optical-Gamma-Ray Flux Increase
: Valverde J, Horan D, Bernard D, Fegan S, Abeysekara AU, Archer A, Benbow W, Bird R, Brill A, Brose R, Buchovecky M, Buckley JH, Christiansen JL, Cui W, Falcone A, Feng Q, Finley JP, Fortson L, Furniss A, Gent A, Gillanders GH, Giuri C, Gueta O, Hanna D, Hassan T, Hervet O, Holder J, Hughes G, Humensky TB, Kaaret P, Kelley-Hoskins N, Kertzman M, Kieda D, Krause M, Krennrich F, Lang MJ, Maier G, Moriarty P, Mukherjee R, Nieto D, Nievas-Rosillo M, O'Brien S, Ong RA, Otte AN, Park N, Petrashyk A, Pfrang K, Pichel A, Pohl M, Prado RR, Pueschel E, Quinn J, Ragan K, Reynolds PT, Ribeiro D, Richards GT, Roache E, Sadeh I, Santander M, Scott SS, Sembroski GH, Shahinyan K, Shang R, Sushch I, Vassiliev VV, Weinstein A, Wells RM, Wilcox P, Wilhelm A, Williams DA, Williamson TJ, Noto G, Edwards PG, Piner BG, Ramazani VF, Hovatta T, Jormanainen J, Lindfors E, Nilsson K, Takalo L, Kovalev YY, Lister ML, Pushkarev AB, Savolainen T, Kiehlmann S, Max-Moerbeck W, Readhead ACS, Lahteenmaki A, Tornikoski M
Publisher: IOP PUBLISHING LTD
: 2020
: Astrophysical Journal
: ASTROPHYSICAL JOURNAL
: ASTROPHYS J
: ARTN 170
: 891
: 2
: 25
: 0004-637X
: 1538-4357
DOI: https://doi.org/10.3847/1538-4357/ab765d
: https://research.utu.fi/converis/portal/detail/Publication/47052301
Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales, especially during flares. With a decade of observations from the Fermi-LAT and VERITAS, we present an extensive study of the long-term multiwavelength radio-to-gamma-ray flux-density variability, with the addition of a couple of short-time radio-structure and optical polarization observations of the blazar 1ES 1215+303 (z = 0.130), with a focus on its gamma-ray emission from 100 MeV to 30 TeV. Multiple strong GeV gamma-ray flares, a long-term increase in the gamma-ray and optical flux baseline, and a linear correlation between these two bands are observed over the ten-year period. Typical HBL behaviors are identified in the radio morphology and broadband spectrum of the source. Three stationary features in the innermost jet are resolved by Very Long Baseline Array at 43.1, 22.2, and 15.3 GHz. We employ a two-component synchrotron self-Compton model to describe different flux states of the source, including the epoch during which an extreme shift in energy of the synchrotron peak frequency from infrared to soft X-rays is observed.
