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Recent observations by H.E.S.S. and MAGIC strongly suggest that the Universe is more transparent to very-high-energy gamma rays than previously thought. We show that this fact can be reconciled with standard blazar emission models provided…

High Energy Astrophysical Phenomena · Physics 2015-05-18 Marco Roncadelli , Alessandro De Angelis , Oriana Mansutti

Recent detection of blazar 3C279 by MAGIC has confirmed previous indications by H.E.S.S. that the Universe is more transparent to very-high-energy gamma rays than currently thought. This circumstance can be reconciled with observations of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Marco Roncadelli , Alessandro De Angelis , Oriana Mansutti

The recent detection of blazar 3C279 by MAGIC has confirmed previous indications by H.E.S.S. that the Universe is more transparent to very-high-energy gamma rays than previously thought. We show that this fact can be reconciled with…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-06 Marco Roncadelli , Alessandro De Angelis , Oriana Mansutti

An anomalously large transparency of the Universe to gamma rays has recently been discovered by the Imaging Atmospheric Cherenkov Telescopes (IACTs) H.E.S.S. and MAGIC. We show that observations can be reconciled with standard blazar…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-30 Marco Roncadelli , Alessandro De Angelis , Oriana Mansutti

Observations with the Imaging Atmospheric Cherenkov Telescopes H.E.S.S., MAGIC, CANGAROO III and VERITAS have shown that the Universe is more transparent than expected to gamma rays above 100GeV. As a natural explanation, the DARMA scenario…

High Energy Astrophysical Phenomena · Physics 2011-02-08 Marco Roncadelli , Alessandro De Angelis , Giorgio Galanti , Massimo Persic

Recent findings by Imaging Atmospheric Cherenkov Telescopes indicate a large transparency of the Universe to gamma rays, which can be hardly explained within the current models of extragalactic background light. We show that the observed…

Astrophysics · Physics 2008-11-26 Alessandro De Angelis , Marco Roncadelli , Oriana Mansutti

Recent findings by gamma-ray Cherenkov telescopes suggest a higher transparency of the Universe to very-high-energy (VHE) photons than expected from current models of the Extragalactic Background Light. It has been shown that such…

Astrophysics · Physics 2009-12-10 A. De Angelis , O. Mansutti , M. Persic , M. Roncadelli

The MAGIC collaboration has recently reported the detection of the strong gamma-ray blazar 3C279 during a 1-2 day flare. They have used their spectral observations to draw conclusions regarding upper limits on the opacity of the Universe to…

Astrophysics · Physics 2009-11-13 Floyd W. Stecker , Sean T. Scully

The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at a distance…

Astrophysics · Physics 2009-02-23 MAGIC Collaboration , J. Albert

In the last couple of years the Magic air Cherenkov telescope has made significant contributions to very high energy $\gamma$-ray astronomy. These include the detection of the galactic binary system LSI +61 303 and the observation of pulsed…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-13 D. Kranich

High energy gamma-ray astronomy is a newly emerging and very successful branch of astronomy and astrophysics. Exciting results have been obtained by the current generation Cherenkov telescope systems such as H.E.S.S., MAGIC, VERITAS and…

Astrophysics · Physics 2019-08-14 G. Hermann , W. Hofmann , T. Schweizer , M. Teshima

3C 279 is one of the best studied flat spectrum radio quasars located at a comparatively large redshift of z = 0.536. Observations in the very high energy band of such distant sources were impossible until recently due to the expected steep…

High Energy Astrophysical Phenomena · Physics 2019-08-13 M. Errando , R. Bock , D. Kranich , E. Lorenz , P. Majumdar , M. Mariotti , D. Mazin , E. Prandini , F. Tavecchio , M. Teshima , R. Wagner

The flat-spectrum radio-quasar 3C279 (z=0.536) is the most distant object detected at very high energy (VHE) gamma-rays. It is thus an important beacon for the study of the interaction of the VHE gamma-rays with the Extra-galactic…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Karsten Berger , Pratik Majumdar , Elina Lindfors , Fabrizio Tavecchio , Masahiro Teshima

We have recently proposed a simplified scenario for blazars in which these sources are classified as flat-spectrum radio quasars or BL Lacs according to the prescriptions of unified schemes, and to a varying combination of Doppler boosted…

High Energy Astrophysical Phenomena · Physics 2015-06-23 P. Padovani , P. Giommi

The quasar 3C 279 is one of the best-studied flat spectrum radio quasars. It is located at a comparatively large redshift of z=0.536: E>100 GeV observations of such distant sources were until recently impossible both due to the expected…

Many extensions of the Standard Model predict the existence of ALPs, which are very light spin-zero bosons with a two-photon coupling. Photon-ALP oscillations occur in the presence of an external magnetic field, and ALPs can lead to…

High Energy Astrophysical Phenomena · Physics 2015-03-19 Alessandro De Angelis , Giorgio Galanti , Marco Roncadelli

Background radiation fields pervade the Universe, and above a certain energy any $\gamma$-ray flux emitted by an extragalactic source should be attenuated due to $e^+e^-$ pair production. The opacity could be alleviated if photons…

High Energy Astrophysical Phenomena · Physics 2014-09-05 Manuel Meyer , Daniele Montanino , Jan Conrad

The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the first stars, which may have formed before…

Astrophysics · Physics 2012-08-27 H. E. S. S. Collaboration , : , F. Aharonian

High-energy photons are a powerful probe for astrophysics and for fundamental physics under extreme conditions. During the recent years, our knowledge of the most violent phenomena in the Universe has impressively progressed thanks to the…

Astrophysics · Physics 2009-09-29 Alessandro De Angelis , Oriana Mansutti , Massimo Persic

Magic Telescope may observe and reveal at horizons lights from air-shower Cherenkov reflections. The ground, the sea, the cloudy sky (below the mountain) may reflect PeVs-EeV UHECR Cherenkov lights observable by MAGIC telescopes. Even…

Astrophysics · Physics 2008-11-26 D. Fargion , M. Gaug , P. Oliva
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