LONG TERM OBSERVATIONS OF B2 1215+30 WITH VERITAS

• Published in: The Astrophysical journal Vol. 779; no. 2; pp. 1 - 9
• Main Authors: Aliu, E, Archambault, S, Arlen, T, Aune, T, BEILICKE, M, Benbow, W, Bird, R, Bouvier, A, Buckley, J H, Bugaev, V
• Format: Journal Article
• Language: English
• Published: United States 20.12.2013
• Subjects: Astroparticle Physics; Astropartikelfysik; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BL LACERTAE OBJECTS; BL Lacertae objects: general; BL Lacertae objects: individual: B2 1215+30 (VER J1217+301); Blazars; COMPARATIVE EVALUATIONS; EMISSION; ENERGY SPECTRA; Flux; GAMMA RADIATION; GEV RANGE; Integrals; PHOTONS; Spectra; Spectral energy distribution; WAVELENGTHS; X RADIATION; X-rays
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.1088/0004-637X/779/2/92

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 (VHEs; E > 100 GeV) by VERITAS with a significance of 8.9[sigma] and showed clear variability on timescales 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 + or - 0.4 sub(stat) + or - 0.3 sub(syst) with an integral flux above 200 GeV of (8.0 + or - 0.9 sub(stat) + or - 3.2 sub(syst)) x 10 super(-12) cm super(-2) s super(-1). No short term variability could be detected during the bright state in 2011. Multi-wavelength data were obtained contemporaneously 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 reproduced well with model parameters typical for VHE-detected BL Lac objects.