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Rapid and multiband variability of the TeV bright active nucleus of the galaxy IC 310

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Antoranz Canales, Pedro and Barrio Uña, Juan Abel and Contreras González, José Luis and Fonseca González, Mª Victoria and López Moya, Marcos and Miranda Pantoja, José Miguel and Satalecka, Konstanzja and Scapin, Valeria (2014) Rapid and multiband variability of the TeV bright active nucleus of the galaxy IC 310. Astronomy & Astrophysics, 563 . ISSN 0004-6361

Official URL: http://dx.doi.org/10.1051/0004-6361/201321938


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Abstract

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.


Item Type:Article
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© ESO, 2014.

Uncontrolled Keywords:Gamma-Ray Emission, Large-Area Telescope, Extragalactic Background Light, Perseus Cluster, Magic Telescopes, Galactic Nuclei, Radio Galaxies, M87, Catalog, Blazars.
Subjects:Sciences > Physics > Electricity
Sciences > Physics > Electronics
Sciences > Physics > Nuclear physics
ID Code:26629
Deposited On:11 Sep 2014 07:49
Last Modified:10 Dec 2018 14:58

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