Long term observations of B2 1215+30 with VERITAS

Abstract

We report on VERITAS observations of the BL Lac object B2 1215+30 between 2008 and 2012. During this period, the source was detected at very high energies (VHE; E > 100 GeV) by VERITAS with a significance of $8.9\sigma$ and showed clear variability on time scales larger than months. In 2011, the source was found to be in a relatively bright state and a power-law fit to the differential photon spectrum yields a spectral index of $3.6\pm 0.4_{\mathrm{stat}}\pm 0.3_{\mathrm{syst}}$ with an integral flux above 200 GeV of $(8.0\pm 0.9_{\mathrm{stat}}\pm 3.2_{\mathrm{syst}})\times 10^{-12}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$. No short term variability could be detected during the bright state in 2011. Multi-wavelength data were obtained contemporaneous with the VERITAS observations in 2011 and cover optical (Super-LOTIS, MDM, Swift-UVOT), X-ray (Swift-XRT), and gamma-ray (Fermi-LAT) frequencies. These were used to construct the spectral energy distribution (SED) of B2 1215+30. A one-zone leptonic model is used to model the blazar emission and the results are compared to those of MAGIC from early 2011 and other VERITAS-detected blazars. The SED can be well reproduced with model parameters typical for VHE-detected BL Lacs.

34 pages, 5 figures, accepted for publication in ApJ

References in corpus (12)

• Fermi Large Area Telescope Bright Gamma-ray Source List
• MAGIC discovery of VHE Emission from the FSRQ PKS 1222+21
• Background Modelling in Very-High-Energy gamma-ray Astronomy
• Paper II: Calibration of the Swift ultraviolet/optical telescope
• VERITAS Observations of the gamma-Ray Binary LS I +61 303
• Host galaxy subtraction of TeV candidate BL Lacertae objects
• Rapid TeV Gamma-Ray Flaring of BL Lacertae
• Discovery of VHE gamma-rays from the blazar 1ES 1215+303 with the MAGIC Telescopes and simultaneous multi-wavelength observations
• Discovery of a new TeV gamma-ray source: VER J0521+211
• Models for the Spectral Energy Distributions and Variability of Blazars
• Multiwavelength observations and modeling of 1ES 1959+650 in a low flux state
• On the Redshift of the Very High Energy Blazar 3C 66A

Cited by in corpus (16)

• The extragalactic background light, the Hubble constant, and anomalies: conclusions from 20 years of TeV gamma-ray observations
• Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013
• Leptonic and Hadronic Radiative Processes in Supermassive-Black-Hole Jets
• First NuSTAR Observations of Mrk 501 within a Radio to TeV Multi-Instrument Campaign
• A decade of multi-wavelength observations of the TeV blazar 1ES 1215+303: Extreme shift of the synchrotron peak frequency and long-term optical-gamma-ray flux increase
• A luminous and isolated gamma-ray flare from the blazar B2 1215+30
• A survey of active galaxies at TeV photon energies with the HAWC gamma-ray observatory
• Prospects for a Multi-TeV Gamma-ray Sky Survey with the LHAASO Water Cherenkov Detector Array
• From Radio to TeV: The surprising Spectral Energy Distribution of AP Librae
• Model-independent Redshift Estimation of BL Lac Objects through VHE Observations
• Infrared emission from dust and the spectral features of extragalactic gamma-ray sources
• Hamburger Sternwarte plate archives: Historic long-term variability study of active galaxies based on digitized photographic plates
• H.E.S.S. discovery of very-high-energy gamma-ray emission of PKS 1440-389
• Prospects of additional contribution at Optical-NIR band of EBL in the light of VHE spectra
• Revisiting the evidences for spectral anomalies in distant blazars: new data on the photon-ALP mixing
• Simultaneously unveiling the EBL and intrinsic spectral parameters of gamma-ray sources with Hamiltonian Monte Carlo