RT Journal Article
T1 Rapid and multiband variability of the TeV bright active nucleus of the galaxy IC 310
A1 Antoranz Canales, Pedro
A1 Barrio Uña, Juan Abel
A1 Contreras González, José Luis
A1 Fonseca González, María Victoria
A1 López Moya, Marcos
A1 Miranda Pantoja, José Miguel
A1 Satalecka, Konstanzja
A1 Scapin, Valeria
AB Context. The radio galaxy IC 310 has recently been identified as a gamma-ray emitter based on observations at GeV energies with Fermi-LAT and at very high energies (VHE, E > 100 GeV) with the MAGIC telescopes. Originally classified as a head-tail radio galaxy, the nature of this object is subject of controversy since its nucleus shows blazar-like behavior. Aims. To understand the nature of IC310 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 gamma-ray regime. Methods. The light curve of IC310 above 300GeV has been measured with the MAGIC telescopes from 2009 October to 2010 February. Contemporaneous Fermi-LAT data (2008-2011) in the 10-500 GeV energy range were also analyzed. In the X-ray regime, archival observations from 2003 to 2007 with XMM-Newton, Chandra, and Swift-XRT in the 0.5-10 keV band were studied. Results. The VHE light curve reveals several high-amplitude and short-duration flares. Day-to-day flux variability is clearly present (>5 sigma). The photon index between 120 GeV and 8 TeV remains at the value Gamma similar to 2.0 during both low and high flux states. The VHE spectral shape does not show significant variability, whereas the flux at 1 TeV changes by a factor of similar to 7. Fermi-LAT detected only eight gamma-ray events in the energy range 10 GeV-500 GeV in three years of observation. The measured photon index of Gamma = 1.3 +/- 0.5 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 +/- 0.07 to 2.55 +/- 0.07. Conclusions. The rapid variability measured in gamma-rays and X-rays confirms the blazar-like behavior of IC310. The multi-TeV gamma-ray emission seems to originate from scales of less than 80 Schwarzschild radii (for a black hole mass of 2 x 10(8) M-circle dot) within the compact core of its FR I radio jet with orientation angle 10 degrees-38 degrees. The spectral energy distribution resembles that of an extreme blazar, albeit the luminosity is more than two orders of magnitude lower.
PB EDP Sciencies
SN 0004-6361
YR 2014
FD 2014-03
LK https://hdl.handle.net/20.500.14352/33633
UL https://hdl.handle.net/20.500.14352/33633
NO © ESO, 2014.
NO German BMBF
NO German MPG
NO Italian INFN
NO Swiss National Fund SNF
NO Spanish MICINN
NO CPAN project of the Spanish Consolider-Ingenio  programme
NO MultiDark project of the Spanish Consolider-Ingenio programme
NO Academy of Finland
NO DFG Cluster of Excellence "Origin and Structure of the Universe"
NO DFG Collaborative Research Centers
NO Polish MNiSzW grant
NO Croatian National Science Foundation
NO National Aeronautics and Space Administration
NO ESA Member States
NO NASA
NO INAF in Italy
NO CNES in France
NO Bundesministerium fur Forschung und Technologie under Deutsches Zentrum fur Luft- und Raumfahrt
DS Docta Complutense
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