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

Journal Article · Thu Sep 01 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/738/1/25· OSTI ID:21582901

Acciari, V A; Benbow, W ^[1]; Aliu, E ^[2]; Arlen, T ^[3]; Aune, T ^[4]; Beilicke, M; Buckley, J H; Bugaev, V; Dickherber, R ^[5]; Boltuch, D ^[6]; Bradbury, S M ^[7]; Byrum, K ^[8]; Cannon, A ^[9]; Cesarini, A ^[10]; Ciupik, L ^[11]; Cui, W; Finley, J P ^[12]; Duke, C ^[13]; Falcone, A ^[14]; Finnegan, G ^[15]

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1. Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States)
2. Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States)
3. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
4. Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States)
5. Department of Physics, Washington University, St. Louis, MO 63130 (United States)
6. Department of Physics and Astronomy and Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States)
7. School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)
8. Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)
9. School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)
10. School of Physics, National University of Ireland Galway, University Road, Galway (Ireland)
11. Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States)
12. Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)
13. Department of Physics, Grinnell College, Grinnell, IA 50112-1690 (United States)
14. Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States)
15. Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States)

We report on TeV {gamma}-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 {gamma}-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 {gamma}-ray energy spectra as a function of time and for different flux levels. On 2008 May 2 and 3, bright TeV {gamma}-ray flares were detected with fluxes reaching the level of 10 Crab. The TeV {gamma}-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 {gamma}-rays. Contemporaneous spectral energy distributions were generated for 18 nights, each of which are reasonably described by a one-zone synchrotron self-Compton model.

• OSTI ID: 21582901
• Journal Information: Astrophysical Journal, Vol. 738, Issue 1; Other Information: DOI: 10.1088/0004-637X/738/1/25; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BL LACERTAE OBJECTS
ENERGY SPECTRA
GALAXIES
GALAXY NUCLEI
GAMMA RADIATION
TIME DEPENDENCE
X RADIATION
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
RADIATIONS
SPECTRA