Astronomy and Astrophysics – Astrophysics – High Energy Astrophysical Phenomena
Scientific paper
2010-04-07
Astronomy and Astrophysics
Astrophysics
High Energy Astrophysical Phenomena
8 pages, 9 figures, accepted for publication in A&A
Scientific paper
Context: Part of the very high energy $\gamma$-ray radiation coming from extragalactic sources is absorbed through the pair production process on the extragalactic background light photons. Extragalactic magnetic fields alter the trajectories of these cascade pairs and, in turn, convert cosmic background photons to gamma-ray energies by inverse Compton scattering. These secondary photons can form an extended halo around bright VHE sources. Aims: We searched for an extended emission around the bright blazars Mrk 421 and Mrk 501 using the MAGIC telescope data. Methods: If extended emission is present, the angular distribution of reconstructed gamma-ray arrival directions around the source is broader than for a point-like source. In the analysis of a few tens of hours of observational data taken from Mrk 421 and Mrk 501 we used a newly developed method that provides better angular resolution. This method is based on the usage of multidimensional decision trees. Comparing the measured shapes of angular distributions with those expected from a point-like source one can detect or constrain possible extended emission around the source. We also studied the influence of different types of systematic errors on the shape of the distribution of reconstructed gamma-ray arrival directions for a point source. Results: We present upper limits for an extended emission calculated for both sources for various source extensions and emission profiles. We discuss possible constraints on the extragalactic magnetic fields strength. We obtain upper limits on the extended emission around the Mrk~421 (Mrk~501) on the level of < 5% (< 4%) of the Crab Nebula flux above the energy threshold of 300 GeV. Using these results we discuss possible constraints on the extragalactic magnetic fields strength around a few times $10^{-15}$~G.
Aleksić J.
Angelis Alessando de
Antonelli Lucio Angelo
Antoranz P.
Backes Michael
No associations
LandOfFree
Search for an extended VHE gamma-ray emission from Mrk 421 and Mrk 501 with the MAGIC Telescope does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Search for an extended VHE gamma-ray emission from Mrk 421 and Mrk 501 with the MAGIC Telescope, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Search for an extended VHE gamma-ray emission from Mrk 421 and Mrk 501 with the MAGIC Telescope will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-397327