VERITAS discovery of {gt} 200 GeV gamma-ray emission from the Intermediate-frequency-peaked BL lac object W Comae.

Journal Article · Mon Sep 01 00:00:00 EDT 2008 · Astrophys. J. Lett.

DOI:https://doi.org/10.1086/592244· OSTI ID:1008272

Acciari, V A; Aliu, E; Beilicke, M; Benbow, W; Bottcher, M; Hays, E; Horan, D; Smith, A W; Wagner, R ^[1]

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1. High Energy Physics

We report the detection of very high energy {gamma}-ray emission from the intermediate-frequency-peaked BL Lacertae object W Comae (z = 0.102) by VERITAS. The source was observed between 2008 January and April. A strong outburst of {gamma}-ray emission was measured in the middle of March, lasting for only 4 days. The energy spectrum measured during the two highest flare nights is fit by a power law and is found to be very steep, with a differential photon spectral index of {Gamma} = 3.81 {+-} 0.35{sub stat} {+-} 0.34{sub syst}. The integral photon flux above 200 GeV during those two nights corresponds to roughly 9% of the flux from the Crab Nebula. Quasi-simultaneous Swift observations at X-ray energies were triggered by the VERITAS observations. The spectral energy distribution of the flare data can be described by synchrotron self-Compton (SSC) or external Compton (EC) leptonic jet models.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: National Science Foundation (NSF); Smithsonian Inst.; NSERC-Canada; Science Foundation Ireland; PPARC
• DOE Contract Number: DE-AC02-06CH11357
• OSTI ID: 1008272
• Report Number(s): ANL-HEP-PR-09-8; TRN: US1101361
• Journal Information: Astrophys. J. Lett., Vol. 684, Issue 2 ; Sep. 2008
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

43 PARTICLE ACCELERATORS
BL LACERTAE OBJECTS
CRAB NEBULA
DETECTION
ENERGY SPECTRA
JET MODEL
PHOTONS
SUPERCONDUCTING SUPER COLLIDER
SYNCHROTRONS