The june 2008 flare of Markarian 421 from optical to TeV energies

© The American Astronomical Society. AGILE is a mission of ASI, with co-participation of INAF and INFN. This work was partially supported by ASI grants I/R/045/04, I/089/06/0, I/011/07/0 and by the Italian Ministry of University and Research (PRIN 2005025417), (ASDC) I/024/05/1. The MAGIC collaboration thanks the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de Los Muchachos in La Palma and support by the German BMBF and MPG, the Italian INFN and Spanish MCINN is acknowledged. This work was supported by ETH Research Grant TH 34/043, by the Polish MNiSzW Grant N N203 390834, the YIP of the Helmholtz Gemeinschaft, the grant of Georgian National Science Foundation GNSF/ST07/4180. E. K. acknowledges financial support from the NCS grant No. 96-2811-M-008-058. The VERITAS collaboration is supported by grants from the U.S. Department of Energy, the National Science Foundation, and the Smithsonian Institution, by NSERC in Canada, Science Foundation Ireland, and PPARC in the UK. We acknowledge the technical support staff at the FLWO. We also acknowledge the Swift Team for carrying out the ToO observation.
We present optical, X-ray, high-energy ((sic) 30 GeV) and very high energy ((sic) 100 GeV; VHE) observations of the high-frequency peaked blazar Mrk 421 taken between 2008 May 24 and June 23. A high-energy gamma-ray signal was detected by AGILE with root TS = 4.5 between June 9 and 15, with F(E > 100 MeV) = 42(-12)(+14) x 10(-8) photons cm(-2) s(-1). This flaring state is brighter than the average flux observed by EGRET by a factor of similar to 3, but still consistent with the highest EGRET flux. In hard X-rays (20-60 keV) SuperAGILE resolved a five-day flare (June 9-15) peaking at similar to 55 mCrab. SuperAGILE, RXTE/ASM and Swift/BAT data show a correlated flaring structure between soft and hard X-rays. Hints of the same flaring behavior are also detected in the simultaneous optical data provided by the GASP-WEBT. A Swift/XRT observation near the flaring maximum revealed the highest 2-10 keV flux ever observed from this source, of 2.6 x 10(-9) erg cm(-2) s(-1) (i.e. > 100 mCrab). A peak synchrotron energy of similar to 3 keV was derived, higher than typical values of similar to 0.5-1 keV. VHE observations with MAGIC and VERITAS between June 6 and 8 showed the flux peaking in a bright state, well correlated with the X-rays. This extraordinary set of simultaneous data, covering a 12-decade spectral range, allowed for a deep analysis of the spectral energy distribution as well as of correlated light curves. The gamma-ray flare can be interpreted within the framework of the synchrotron self-Compton model in terms of a rapid acceleration of leptons in the jet.
ASI
Italian Ministry of University and Research
ASDC
ETH Research
Polish MNiSzW
Helmholtz Gemeinschaft
Georgian National Science Foundation
NCS
U.S. Department of Energy
National Science Foundation
Smithsonian Institution
NSERC in Canada
Science Foundation Ireland
PPARC in the UK
Depto. de Estructura de la Materia, Física Térmica y Electrónica
Fac. de Ciencias Físicas
TRUE
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