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TeV AND MULTI-WAVELENGTH OBSERVATIONS OF Mrk 421 IN 2006-2008
Journal article   Open access   Peer reviewed

TeV AND MULTI-WAVELENGTH OBSERVATIONS OF Mrk 421 IN 2006-2008

V. A Acciari, E Aliu, K Byrum, A Cannon, A Cesarini, L Ciupik, W Cui, R Dickherber, C Duke, A Falcone, …
The Astrophysical journal, Vol.738(1), p.25
2011
DOI: 10.1088/0004-637X/738/1/25
url
https://doi.org/10.1088/0004-637X/738/1/25View
Published (Version of record) Open Access

Abstract

We report on TeV γ-ray observations of the blazar Mrk 421 (redshift of 0.031) with the VERITAS observatory and the Whipple 10 m Cherenkov telescope. The excellent sensitivity of VERITAS allowed us to sample the TeV γ-ray fluxes and energy spectra with unprecedented accuracy where Mrk 421 was detected in each of the pointings. A total of 47.3 hr of VERITAS and 96 hr of Whipple 10 m data were acquired between 2006 January and 2008 June. We present the results of a study of the TeV γ-ray energy spectra as a function of time and for different flux levels. On 2008 May 2 and 3, bright TeV γ-ray flares were detected with fluxes reaching the level of 10 Crab. The TeV γ-ray data were complemented with radio, optical, and X-ray observations, with flux variability found in all bands except for the radio wave band. The combination of the Rossi X-ray Timing Explorer and Swift X-ray data reveal spectral hardening with increasing flux levels, often correlated with an increase of the source activity in TeV γ-rays. Contemporaneous spectral energy distributions were generated for 18 nights, each of which are reasonably described by a one-zone synchrotron self-Compton model.
Astronomy Earth, ocean, space Exact sciences and technology

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