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Variable very high energy gamma-ray emission from Markarian 501

(MAGIC Collaboration) Albert, J.; Aliu, E.; Anderhub, H.; Antoranz, P.; Armada, A.; Baixeras, C.; Barrio, J. A.; Bartko, H.; Bastieri, D.; Becker, J. K.; Bednarek, W.; Berger, K.; Bigongiari, C.; Biland, A.; Bock, R. K.; Bordas, P.; Bosch-Ramon, V.; Bretz, T.; Britvitch, I.; Camara, M.; Carmona, E.; Chilingarian, A.; Coarasa, J. A.; Commichau, S.; Contreras, J. L.; Cortina, J.; Costado, M. T.; Curtef, V.; Danielyan, V.; Dazzi, F.; De Angelis, A.; Delgado, C.; de los Reyes, R.; De Lotto, B.; Domingo-Santamaria, E.; Dorner, D.; Doro, M.; Errando, M.; Fagiolini, M.; Ferenc, D.; Fernandez, E.; Firpo, R.; Flix, J.; Fonseca, M. V.; Font, L.; Fuchs, M.; Galante, N.; Garcia-Lopez, R. J.; Garczarczyk, M.; Gaug, M.; Giller, M.; Goebel, F.; Hakobyan, D.; Hayashida, M.; Hengstebeck, T.; Herrero, A.; Hoehne, D.; Hose, J.; Hrupec, D.; Hsu, C. C.; Jacon, P.; Jogler, T.; Kosyra, R.; Kranich, D.; Kritzer, R.; Laille, A.; Lindfors, E.; Lombardi, S.; Longo, F.; Lopez, J.; Lopez, M.; Lorenz, E.; Majumdar, P.; Maneva, G.; Mannheim, K.; Mansutti, O.; Mariotti, M.; Martinez, M.; Mazin, D.; Merck, C.; Meucci, M.; Meyer, M.; Miranda, J. M.; Mirzoyan, R.; Mizobuchi, S.; Moralejo, A.; Nieto, D.; Nilsson, K.; Ninkovic, J.; Ona-Wilhelmi, E.; Otte, N.; Oya, I.; Paneque, D.; Panniello, M.; Paoletti, R.; Paredes, J. M.; Pasanen, M.; Pascoli, D.; Pauss, F.; Pegna, R.; Persic, M.; Peruzzo, L.; Piccioli, A.; Prandini, E.; Puchades, N.; Raymers, A.; Rhode, W.; Ribo, M.; Rico, J.; Rissi, M.; Robert, A.; Ruegamer, S.; Saggion, A.; Saito, T.; Sanchez, A.; Sartori, P.; Scalzotto, V.; Scapin, V.; Schmitt, R.; Schweizer, T.; Shayduk, M.; Shinozaki, K.; Shore, S. N.; Sidro, N.; Sillanpaa, A.; Sobczynska, D.; Stamerra, A.; Stark, L. S.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Tescaro, D.; Teshima, M.; Torres, D. F.; Turini, N.; Vankov, H.; Vitale, V.; Wagner, R. M.; Wibig, T.; Wittek, W.; Zandanel, F.; Zanin, R.; Zapatero, J. (2007) Variable very high energy gamma-ray emission from Markarian 501. The Astrophysical Journal, 669 . pp. 862-883. ISSN 0004-637X

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Abstract

The blazar Markarian 501 (Mrk 501) was observed at energies above 0.10 TeV with the MAGIC telescope from May through July 2005. The high sensitivity of the instrument enabled the determination of the flux and spectrum of the source on a night-by-night basis. Throughout our observational campaign, the flux from Mrk 501 was found to vary by an order of magnitude. Intra-night flux variability with flux-doubling times down to 2 minutes was observed during the two most active nights, namely June 30 and July 9. These are the fastest flux variations ever observed in Mrk 501. The ~20-minute long flare of July 9 showed an indication of a 4 +/- 1 min time delay between the peaks of F(<0.25 TeV) and F(>1.2 TeV), which may indicate a progressive acceleration of electrons in the emitting plasma blob. The flux variability was quantified for several energy ranges, and found to increase with the energy of the gamma-ray photons. The spectra hardened significantly with increasing flux, and during the two most active nights, a spectral peak was clearly detected at 0.43 +/- 0.06 TeV and 0.25 +/- 0.07 TeV, respectively for June 30 and July 9. There is no evidence of such spectral feature for the other nights at energies down to 0.10 TeV, thus suggesting that the spectral peak is correlated with the source luminosity. These observed characteristics could be accommodated in a Synchrotron-Self-Compton (SSC) framework in which the increase in gamma-ray flux is produced by a freshly injected (high energy) electron population.

Item Type: Article
Uncontrolled Keywords: Markarian 50; BL Lac; AGN; VHE gamma-ray; imaging air Cherenkov telescope; MAGIC
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Divisions: Division of Experimental Physics
Projects:
Project titleProject leaderProject codeProject type
Foton-atom međudjelovanje i korelacije[118624] Tihomir Surić098-0982931-2875MZOS
Depositing User: Dario Hrupec
Date Deposited: 09 Jun 2014 13:26
Last Modified: 24 Jan 2017 12:23
URI: http://fulir.irb.hr/id/eprint/1362
DOI: 10.1086/521382

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