Rapid and multi-band variability of the TeV-bright active nucleus of the galaxy IC 310

(MAGIC Collaboration) Aleksie, J.; Antonelli, L. A.; Antoranz, P.; Babic, A.; de Almeida, U. Barres; Barrio, J. A.; Becerra Gonzalez, J.; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnefoy, S.; Bonnoli, G.; Tridon, D. Borla; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Carreto Fidalgo, D.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; Delgado Mendez, C.; De Lotto, B.; Doert, M.; Dominguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Eisenacher, D.; Elsaesser, D.; Farina, E.; Ferenc, D.; Fonseca, M. V.; Font, L.; Fruck, C.; Garcia Lopez, R. J.; Garczarczyk, M.; Terrats, D. Garrido; Gaug, M.; Giavitto, G.; Godinovic, N.; Gonzalez Munoz, A.; Gozzini, S. R.; Hadamek, A.; Hadasch, D.; Haefner, D.; Herrero, A.; Hose, J.; Hrupec, D.; Idec, W.; Kadenius, V.; Knoetig, M. L.; Kraehenbuehl, T.; Krause, J.; Kushida, J.; La Barbera, A.; Lelas, D.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; Lopez-Coto, R.; Lopez, M.; Lopez-Oramas, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martinez, M.; Masbou, J.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moldon, J.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Niedzwiecki, A.; Nilsson, K.; Nowak, N.; Orito, R.; Overkemping, A.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Partini, S.; Persic, M.; Prada, F.; PradaMoroni, P. G.; Prandini, E.; Preziuso, S.; Puljak, I.; Reichardt, I.; Reinthal, R.; Rhode, W.; Ribo, M.; Rico, J.; Ruegamer, S.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpaeae, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamatescu, V.; Stamerra, A.; Steinke, B.; Storz, J.; Sun, S.; Suric, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzic, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Uellenbeck, M.; Vogler, P.; Wagner, R. M.; Weitzel, Q.; Zandanel, F.; Zanin, R.; Dauser, T.; Fortin, P.; Kadler, M.; Krauss, F.; Wilbert, S.; Wilms, J.; (2014) Rapid and multi-band variability of the TeV-bright active nucleus of the galaxy IC 310. Astronomy and Astrophysics, 563 . A91-1. ISSN 0004-6361

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Abstract

The galaxy IC 310 has recently been identified as a $\gamma$-ray emitter by the Fermi-LAT and at very high energies by the MAGIC telescopes. Originally classified as a head-tail radio galaxy, the nature of this object is subject of controversy because its nucleus shows blazar-like behavior. In order to understand the nature of IC 310 and the origin of the VHE emission we studied the spectral and flux variability of IC 310 from the X-ray band to the VHE regime. The daily light curve of IC 310 above 300 GeV has been measured with MAGIC from 2009 October to 2010 February. Contemporaneous Fermi-LAT data (2008-2011) in the 10-500 GeV energy range were also analyzed. In X-ray, archival observations from 2003 to 2007 with XMM-Newton, Chandra, and Swift-XRT in the 0.5-10 keV band were studied. Several flares with similar amplitude can be seen in the MAGIC light curve. Day to day flux variability is clearly present. The photon index between 120 GeV and 8 TeV is measured to be $\Gamma=2.0$ during both low and high flux states. It does not show variability, whereas the flux at 1 TeV changes by a factor of 7. Fermi-LAT detected only eight $\gamma$ rays in the energy range 10 GeV-500 GeV in three years of observation. The measured photon index of $\Gamma=1.3\pm0.5$ in the Fermi-LAT range is very hard. The X-ray measurements show strong variability in both flux and photon index. The latter varied from 1.76 to 2.55. The rapid variability measured in $\gamma$ rays and X-rays confirms the blazar-like behavior of the source. The spectral behavior measured in both energy bands suggest IC 310 could be linked to extreme HBL objects. The apparent luminosity of IC 310 is a few orders of magnitude lower than other extreme HBLs however and, atypical for an HBL, it harbors a kiloparsec-scale radio structure. Thus, IC 310 could be a peculiar type of a HBL.

Item Type:	Article
Uncontrolled Keywords:	Galaxies: active; Galaxies: individual: IC 310; Gamma rays: galaxies, X-rays: galaxies
Subjects:	NATURAL SCIENCES > Physics NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Divisions:	Division of Experimental Physics
Depositing User:	Dario Hrupec
Date Deposited:	22 Jan 2015 13:20
URI:	http://fulir.irb.hr/id/eprint/1662
DOI:	10.1051/0004-6361/201321938

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