The June 2008 Flare of Markarian 421 from Optical to TeV Energies

Donnarumma, I.; Vittorini, V.; Vercellone, S.; del Monte, E.; Feroci, M.; D'Ammando, F.; Pacciani, L.; Chen, A. W.; Tavani, M.; Bulgarelli, A.; Giuliani, A.; Longo, F.; Pucella, G.; Argan, A.; Barbiellini, G.; Boffelli, F.; Caraveo, P.; Cattaneo, P. W.; Cocco, V.; Costa, E.; DeParis, G.; Di Cocco, G.; Evangelista, Y.; Fiorini, M.; Froysland, T.; Frutti, M.; Fuschino, F.; Galli, M.; Gianotti, F.; Labanti, C.; Lapshov, I.; Lazzarotto, F.; Lipari, P.; Marisaldi, M.; Mastropietro, M.; Mereghetti, S.; Morelli, E.; Morselli, A.; Pellizzoni, A.; Perotti, F.; Picozza, P.; Porrovecchio, G.; Prest, M.; Rapisarda, M.; Rappoldi, A.; Rubini, A.; Soffitta, P.; Trifoglio, M.; Trois, A.; Vallazza, E.; Zambra, A.; Zanello, D.; Pittori, C.; Santolamazza, P.; Verrecchia, F.; Giommi, P.; Colafrancesco, S.; Salotti, L.; Villata, M.; Raiteri, C. M.; Chen, W. P.; Efimova, N. V.; Jordan, B.; Konstantinova, T. S.; Koptelova, E.; Kurtanidze, O. M.; Larionov, V. M.; Ros, J. A.; Sadun, A. C.; Anderhub, H.; Antonelli, L. A.; Antoranz, P.; Backes, M.; Baixeras, C.; Balestra, S.; Barrio, J. A.; Bartko, H.; Bastieri, D.; González, J. Becerra; Becker, J. K.; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Bock, R. K.; Bonnoli, G.; Bordas, P.; Tridon, D. Borla; Bosch-Ramon, V.; Bretz, T.; Britvitch, I.; Camara, M.; Carmona, E.; Chilingarian, A.; Commichau, S.; Contreras, J. L.; Cortina, J.; Costado, M. T.; Covino, S.; Curtef, V. et al.
Bibliographical reference

The Astrophysical Journal Letters, Volume 691, Issue 1, pp. L13-L19 (2009).

Advertised on:
1
2009
Number of authors
295
IAC number of authors
6
Citations
109
Refereed citations
83
Description
We present optical, X-ray, high-energy (lap30 GeV) and very high energy (gap100 GeV; VHE) observations of the high-frequency peaked blazar Mrk 421 taken between 2008 May 24 and June 23. A high-energy γ-ray signal was detected by AGILE with √{TS}=4.5 between June 9 and 15, with F(E>100 MeV) = 42+14 -12 × 10-8 photons cm-2 s-1. This flaring state is brighter than the average flux observed by EGRET by a factor of ~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 ~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 × 10-9 erg cm-2 s-1 (i.e. >100 mCrab). A peak synchrotron energy of ~3 keV was derived, higher than typical values of ~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 γ-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.
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The MAGIC Collaboration is integrated by 20 research institutes and university departments from Armenia, Bulgaria, Finland, Germany, Italy, Poland, Spain, Switzerland and USA. The collaboration comprises two 17m diameter telescopes, located at the Roque de los Muchachos Observatory, designed to measure the Cherenkov radiation associated with

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