@article {2012A\&A...544A..96A, title = {{MAGIC observations of the giant radio galaxy M 87 in a low-emission state between 2005 and 2007}}, journal = {Astronomy and Astrophysics}, volume = {544}, year = {2012}, month = {aug}, pages = {A96}, abstract = {Context. We present the results of a long M 87 monitoring campaign in very high energy {$\gamma$}-rays with the MAGIC-I Cherenkov telescope.
Aims: We aim to model the persistent non-thermal jet emission by monitoring and characterizing the very high energy {$\gamma$}-ray emission of M 87 during a low state.
Methods: A total of 150 h of data were taken between 2005 and 2007 with the single MAGIC-I telescope, out of which 128.6 h survived the data quality selection. We also collected data in the X-ray and Fermi-LAT bands from the literature (partially contemporaneous).
Results: No flaring activity was found during the campaign. The source was found to be in a persistent low-emission state, which was at a confidence level of 7{$\sigma$}. We present the spectrum between 100 GeV and 2 TeV, which is consistent with a simple power law with a photon index {$\Gamma$} = 2.21 {\plusmn} 0.21 and a flux normalization at 300 GeV of (7.7 {\plusmn} 1.3) {\times} 10$^{-8}$ TeV$^{-1}$ s$^{-1}$ m$^{-2}$. The extrapolation of the MAGIC spectrum into the GeV energy range matches the previously published Fermi-LAT spectrum well, covering a combined energy range of four orders of magnitude with the same spectral index. We model the broad band energy spectrum with a spine layer model, which can satisfactorily describe our data.}, keywords = {galaxies: individual: M 87, gamma rays: galaxies}, doi = {10.1051/0004-6361/201117827}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...544A..96A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Caneva, G. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Gaug, M. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Kellermann, H. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and L{\'o}pez-Oramas, A. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamatescu, V. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Uellenbeck, M. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and Ghisellini, G.} } @article {2012A\&A...542A.100A, title = {{Mrk 421 active state in 2008: the MAGIC view, simultaneous multi-wavelength observations and SSC model constrained}}, journal = {Astronomy and Astrophysics}, volume = {542}, year = {2012}, month = {jun}, pages = {A100}, abstract = {Context. The blazar Markarian 421 is one of the brightest TeV gamma-ray sources of the northern sky. From December 2007 until June 2008 it was intensively observed in the very high energy (VHE, E {\gt} 100 GeV) band by the single-dish Major Atmospheric Gamma-ray Imaging Cherenkov telescope (MAGIC-I).
Aims: We aimed to measure the physical parameters of the emitting region of the blazar jet during active states.
Methods: We performed a dense monitoring of the source in VHE with MAGIC-I, and also collected complementary data in soft X-rays and optical-UV bands; then, we modeled the spectral energy distributions (SED) derived from simultaneous multi-wavelength data within the synchrotron self-Compton (SSC) framework.
Results: The source showed intense and prolonged {$\gamma$}-ray activity during the whole period, with integral fluxes (E {\gt} 200 GeV) seldom below the level of the Crab Nebula, and up to 3.6 times this value. Eight datasets of simultaneous optical-UV (KVA, Swift/UVOT), soft X-ray (Swift/XRT) and MAGIC-I VHE data were obtained during different outburst phases. The data constrain the physical parameters of the jet, once the spectral energy distributions obtained are interpreted within the framework of a single-zone SSC leptonic model.
Conclusions: The main outcome of the study is that within the homogeneous model high Doppler factors (40 {\l}e} {$δ$} {\l}e} 80) are needed to reproduce the observed SED; but this model cannot explain the observed short time-scale variability, while it can be argued that inhomogeneous models could allow for less extreme Doppler factors, more intense magnetic fields and shorter electron cooling times compatible with hour or sub-hour scale variability.}, keywords = {BL Lacertae objects: individual: Mrk 421, radiation mechanisms: non-thermal}, doi = {10.1051/0004-6361/201117442}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...542A.100A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Caneva, G. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Kellermann, H. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, A. and L{\'o}pez, M. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Uellenbeck, M. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} } @article {2011ApJ...730L...8A, title = {{MAGIC Discovery of Very High Energy Emission from the FSRQ PKS 1222+21}}, journal = {The Astrophysical Journal Letters}, volume = {730}, year = {2011}, month = {mar}, pages = {L8}, abstract = {{Very high energy (VHE) {$\gamma$}-ray emission from the flat spectrum radio quasar (FSRQ) PKS 1222+21 (4C 21.35}, keywords = {cosmic background radiation, galaxies: active, galaxies: jets, gamma rays: galaxies, quasars: individual: PKS 1222+21}, doi = {10.1088/2041-8205/730/1/L8}, url = {http://adsabs.harvard.edu/abs/2011ApJ...730L...8A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Thom, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and MAGIC Collaboration and Tanaka, Y.~T. and Wood, D.~L. and Buson, S.} } @article {2011A\&A...530A...4A, title = {{MAGIC Observations and multiwavelength properties of the quasar 3C 279 in 2007 and 2009}}, journal = {Astronomy and Astrophysics}, volume = {530}, year = {2011}, month = {jun}, pages = {A4}, abstract = {Context. 3C 279, the first quasar discovered to emit VHE {$\gamma$}-rays by the MAGIC telescope in 2006, was reobserved by MAGIC in January 2007 during a major optical flare and from December 2008 to April 2009 following an alert from the Fermi space telescope on an exceptionally high {$\gamma$}-ray state.
Aims: The January 2007 observations resulted in a detection on January 16 with significance 5.4{$\sigma$}, corresponding to a F ({\gt}150 GeV) (3.8 {\plusmn} 0.8) {\times} 10$^{-11}$ ph cm$^{-2}$ s$^{-1}$ while the overall data sample does not show significant signal. The December 2008-April 2009 observations did not detect the source. We study the multiwavelength behaviour of the source at the epochs of MAGIC observations, collecting quasi-simultaneous data at optical and X-ray frequencies and for 2009 also {$\gamma$}-ray data from Fermi.
Methods: We study the light curves and spectral energy distribution of the source. The spectral energy distributions of three observing epochs (including the February 2006, which has been previously published) are modelled with one-zone inverse Compton models and the emission on January 16, 2007 also with two zone model and with a lepto-hadronic model.
Results: We find that the VHE {$\gamma$}-ray emission detected in 2006 and 2007 challenges standard one-zone model, based on relativistic electrons in a jet scattering broad line region photons, while the other studied models fit the observed spectral energy distribution more satisfactorily.}, keywords = {gamma rays: galaxies, quasars: individual: 3C 279}, doi = {10.1051/0004-6361/201116497}, url = {http://adsabs.harvard.edu/abs/2011A\%26A...530A...4A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and R{\"u}ger, M. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Thom, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} } @article {2010ApJ...721..843A, title = {{Magic Constraints on {$\gamma$}-ray Emission from Cygnus X-3}}, journal = {The Astrophysical Journal}, volume = {721}, year = {2010}, month = {sep}, pages = {843-855}, abstract = {Cygnus X-3 is a microquasar consisting of an accreting compact object orbiting around a Wolf-Rayet star. It has been detected at radio frequencies and up to high-energy {$\gamma$} rays (above 100 MeV). However, many models also predict a very high energy (VHE) emission (above hundreds of GeV) when the source displays relativistic persistent jets or transient ejections. Therefore, detecting such emission would improve the understanding of the jet physics. The imaging atmospheric Cherenkov telescope MAGIC observed Cygnus X-3 for about 70 hr between 2006 March and 2009 August in different X-ray/radio spectral states and also during a period of enhanced {$\gamma$}-ray emission. MAGIC found no evidence for a VHE signal from the direction of the microquasar. An upper limit to the integral flux for energies higher than 250 GeV has been set to 2.2 {\times} 10$^{-12}$ photons cm$^{-2}$ s$^{-1}$ (95\% confidence level). This is the best limit so far to the VHE emission from this source. The non-detection of a VHE signal during the period of activity in the high-energy band sheds light on the location of the possible VHE radiation favoring the emission from the innermost region of the jets, where absorption is significant. The current and future generations of Cherenkov telescopes may detect a signal under precise spectral conditions.}, keywords = {acceleration of particles, binaries: general, gamma rays: general, methods: observational, X-rays: binaries}, doi = {10.1088/0004-637X/721/1/843}, url = {http://adsabs.harvard.edu/abs/2010ApJ...721..843A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Baixeras, C. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Britzger, D. and Camara, M. and Carmona, E. and Carosi, A. and Colin, P. and Contreras, J.~L. and Cortina, J. and Costado, M.~T. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Gaug, M. and Godinovi{\'c}, N. and G{\"o}ebel, F. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Hsu, C.~C. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and La Barbera, A. and Laille, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moles, M. and Moralejo, A. and Nieto, D. and Nilsson, K. and Ninkovic, J. and Orito, R. and Oya, I. and Paiano, S. and Paoletti, R. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pascoli, D. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Prada, F. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Rhode, W. and Rib{\'o}, M. and Rico, J. and Rissi, M. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Vankov, H. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and MAGIC Collaboration} } @article {2010ApJ...710..634A, title = {{MAGIC Gamma-ray Telescope Observation of the Perseus Cluster of Galaxies: Implications for Cosmic Rays, Dark Matter, and NGC 1275}}, journal = {The Astrophysical Journal}, volume = {710}, year = {2010}, month = {feb}, pages = {634-647}, abstract = {The Perseus galaxy cluster was observed by the MAGIC Cherenkov telescope for a total effective time of 24.4 hr during 2008 November and December. The resulting upper limits on the {$\gamma$}-ray emission above 100 GeV are in the range of 4.6-7.5 {\times} 10$^{-12}$ cm$^{-2}$ s$^{-1}$ for spectral indices from -1.5 to -2.5, thereby constraining the emission produced by cosmic rays, dark matter annihilations, and the central radio galaxy NGC 1275. Results are compatible with cosmological cluster simulations for the cosmic-ray-induced {$\gamma$}-ray emission, constraining the average cosmic ray-to-thermal pressure to {\l}t}4\% for the cluster core region ({\l}t}8\% for the entire cluster). Using simplified assumptions adopted in earlier work (a power-law spectrum with an index of -2.1, constant cosmic ray-to-thermal pressure for the peripheral cluster regions while accounting for the adiabatic contraction during the cooling flow formation), we would limit the ratio of cosmic ray-to-thermal energy to E $_{CR}$/E $_{th}$ {\l}t} 3\%. Improving the sensitivity of this observation by a factor of about 7 will enable us to scrutinize the hadronic model for the Perseus radio mini-halo: a non-detection of {$\gamma$}-ray emission at this level implies cosmic ray fluxes that are too small to produce enough electrons through hadronic interactions with the ambient gas protons to explain the observed synchrotron emission. The upper limit also translates into a level of {$\gamma$}-ray emission from possible annihilations of the cluster dark matter (the dominant mass component) that is consistent with boost factors of \~{}10$^{4}$ for the typically expected dark matter annihilation-induced emission. Finally, the upper limits obtained for the {$\gamma$}-ray emission of the central radio galaxy NGC 1275 are consistent with the recent detection by the Fermi-LAT satellite. Due to the extremely large Doppler factors required for the jet, a one-zone synchrotron self-Compton model is implausible in this case. We reproduce the observed spectral energy density by using the structured jet (spine-layer) model which has previously been adopted to explain the high-energy emission of radio galaxies.}, keywords = {galaxies: clusters: individual: Perseus, gamma rays: general}, doi = {10.1088/0004-637X/710/1/634}, url = {http://adsabs.harvard.edu/abs/2010ApJ...710..634A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Baixeras, C. and Balestra, S. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Bock, R.~K. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Britzger, D. and Camara, M. and Carmona, E. and Carosi, A. and Colin, P. and Commichau, S. and Contreras, J.~L. and Cortina, J. and Costado, M.~T. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and de los Reyes, R. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Galante, N. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Gaug, M. and Godinovi{\'c}, N. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Hsu, C.~C. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and La Barbera, A. and Laille, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moles, M. and Moralejo, A. and Nieto, D. and Nilsson, K. and Ninkovic, J. and Orito, R. and Oya, I. and Paiano, S. and Paoletti, R. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pascoli, D. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Prada, F. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Rhode, W. and Rib{\'o}, M. and Rico, J. and Rissi, M. and R{\"u}gamer, S. and Saggion, A. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M.~A. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Vankov, H. and Wagner, R.~M. and Zabalza, V. and Zandanel, F. and Zanin, R. and Zapatero, J. and Pfrommer, C. and Pinzke, A. and En{\ss}lin, T.~A. and Inoue, S. and Ghisellini, G. and MAGIC Collaboration} } @article {2010A\&A...517A...5A, title = {{MAGIC observation of the GRB 080430 afterglow}}, journal = {Astronomy and Astrophysics}, volume = {517}, year = {2010}, month = {jul}, pages = {A5}, abstract = {Context. Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of gamma-ray bursts during the prompt phase, i.e. the initial burst of high-energy radiation, and during the long-lasting afterglows. In spite of many successes in interpreting these phenomena, there are still several open key questions about the fundamental emission processes, their energetics and the environment.
Aims: Independently of specific gamma-ray burst theoretical recipes, spectra in the GeV/TeV range are predicted to be remarkably simple, being satisfactorily modeled with power-laws, and therefore offer a very valuable tool to probe the extragalactic background light distribution. Furthermore, the simple detection of a component at very-high energies, i.e. at \~{}100 GeV, would solve the ambiguity about the importance of various possible emission processes, which provide barely distinguishable scenarios at lower energies.
Methods: We used the results of the MAGIC telescope observation of the moderate resdhift (z \~{} 0.76) GRB 080430 at energies above about 80 GeV, to evaluate the perspective for late-afterglow observations with ground based GeV/TeV telescopes.
Results: We obtained an upper limit of F$_{95\% CL}$ = 5.5 {\times} 10$^{-11}$ erg cm$^{-2}$ s$^{-1}$ for the very-high energy emission of GRB 080430, which cannot set further constraints on the theoretical scenarios proposed for this object also due to the difficulties in modeling the low-energy afterglow. Nonetheless, our observations show that Cherenkov telescopes have already reached the required sensitivity to detect the GeV/TeV emission of GRBs at moderate redshift (z {\l}sim} 0.8), provided the observations are carried out at early times, close to the onset of their afterglow phase.}, keywords = {gamma-ray burst: individual: GRB 080430, radiation mechanisms: non-thermal}, doi = {10.1051/0004-6361/200913461}, url = {http://adsabs.harvard.edu/abs/2010A\%26A...517A...5A}, author = {Aleksi{\'c}, J. and Anderhub, H. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Baixeras, C. and Balestra, S. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Becker, J.~K. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Bock, R.~K. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Britzger, D. and Camara, M. and Carmona, E. and Carosi, A. and Colin, P. and Commichau, S. and Contreras, J.~L. and Cortina, J. and Costado, M.~T. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and de los Reyes, R. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fern{\'a}ndez, E. and Firpo, R. and Fonseca, M.~V. and Font, L. and Galante, N. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Gaug, M. and Godinovi{\'c}, N. and G{\"o}ebel, F. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Hsu, C.~C. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and La Barbera, A. and Laille, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moles, M. and Moralejo, A. and Nieto, D. and Nilsson, K. and Ninkovic, J. and Orito, R. and Oya, I. and Paoletti, R. and Paredes, J.~M. and Pasanen, M. and Pascoli, D. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Prada, F. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Rhode, W. and Rib{\'o}, M. and Rico, J. and Rissi, M. and R{\"u}gamer, S. and Saggion, A. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Strah, N. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Turini, N. and Vankov, H. and Wagner, R.~M. and Zabalza, V. and Zandanel, F. and Zanin, R. and Zapatero, J. and de Ugarte-Postigo, A. and MAGIC Collaboration} } @article {2010A\&A...519A..32A, title = {{MAGIC TeV gamma-ray observations of Markarian 421 during multiwavelength campaigns in 2006}}, journal = {Astronomy and Astrophysics}, volume = {519}, year = {2010}, month = {sep}, pages = {A32}, abstract = {Context. Wide-range spectral coverage of blazar-type active galactic nuclei is of paramount importance for understanding the particle acceleration mechanisms assumed to take place in their jets. The Major Atmospheric Gamma Imaging Cerenkov (MAGIC) telescope participated in three multiwavelength (MWL) campaigns, observing the blazar Markarian (Mkn) 421 during the nights of April 28 and 29, 2006, and June 14, 2006.
Aims: We analyzed the corresponding MAGIC very-high energy observations during 9 nights from April 22 to 30, 2006 and on June 14, 2006. We inferred light curves with sub-day resolution and night-by-night energy spectra.
Methods: MAGIC detects {$\gamma$}-rays by observing extended air showers in the atmosphere. The obtained air-shower images were analyzed using the standard MAGIC analysis chain.
Results: A strong {$\gamma$}-ray signal was detected from Mkn 421 on all observation nights. The flux (E {\gt} 250 GeV) varied on night-by-night basis between (0.92{\plusmn}0.11) {\times} 10$^{-10}$ cm$^{-2}$ s$^{-1}$ (0.57 Crab units) and (3.21{\plusmn}0.15) {\times} 10$^{-10}$ cm$^{-2}$ s$^{-1}$ (2.0 Crab units) in April 2006. There is a clear indication for intra-night variability with a doubling time of 36{\plusmn}10\_stat min on the night of April 29, 2006, establishing once more rapid flux variability for this object. For all individual nights {$\gamma$}-ray spectra could be inferred, with power-law indices ranging from 1.66 to 2.47. We did not find statistically significant correlations between the spectral index and the flux state for individual nights. During the June 2006 campaign, a flux substantially lower than the one measured by the Whipple 10-m telescope four days later was found. Using a log-parabolic power law fit we deduced for some data sets the location of the spectral peak in the very-high energy regime. Our results confirm the indications of rising peak energy with increasing flux, as expected in leptonic acceleration models.}, keywords = {BL Lacertae objects: individual: Mkn 421, gamma rays: galaxies, radiation mechanisms: non-thermal}, doi = {10.1051/0004-6361/200913945}, url = {http://adsabs.harvard.edu/abs/2010A\%26A...519A..32A}, author = {Aleksi{\'c}, J. and Anderhub, H. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Baixeras, C. and Balestra, S. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Becker, J.~K. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Bock, R.~K. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Britzger, D. and Camara, M. and Carmona, E. and Carosi, A. and Colin, P. and Commichau, S. and Contreras, J.~L. and Cortina, J. and Costado, M.~T. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and de los Reyes, R. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Gaug, M. and Godinovi{\'c}, N. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Hsu, C.~C. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and La Barbera, A. and Laille, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moles, M. and Moralejo, A. and Nieto, D. and Nilsson, K. and Ninkovic, J. and Orito, R. and Oya, I. and Paoletti, R. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pascoli, D. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Prada, F. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Rhode, W. and Rib{\'o}, M. and Rico, J. and Rissi, M. and R{\"u}gamer, S. and Saggion, A. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Strah, N. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Vankov, H. and Wagner, R.~M. and Zabalza, V. and Zandanel, F. and Zanin, R. and MAGIC Collaboration} } @article {2010ApJ...725.1629A, title = {{MAGIC Upper Limits for Two Milagro-detected Bright Fermi Sources in the Region of SNR G65.1+0.6}}, journal = {The Astrophysical Journal}, volume = {725}, year = {2010}, month = {dec}, pages = {1629-1632}, abstract = {We report on the observation of the region around supernova remnant G65.1+0.6 with the stand-alone MAGIC-I telescope. This region hosts the two bright GeV gamma-ray sources 1FGL J1954.3+2836 and 1FGL J1958.6+2845. They are identified as GeV pulsars and both have a possible counterpart detected at about 35 TeV by the Milagro observatory. MAGIC collected 25.5 hr of good quality data and found no significant emission in the range around 1 TeV. We therefore report differential flux upper limits, assuming the emission to be point-like ({\l}t}=0fdg1) or within a radius of 0fdg3. In the point-like scenario, the flux limits around 1 TeV are at the level of 3\% and 2\% of the Crab Nebula flux for the two sources, respectively. This implies that the Milagro emission is either extended over a much larger area than our point-spread function or it must be peaked at energies beyond 1 TeV, resulting in a photon index harder than 2.2 in the TeV band.}, keywords = {ISM: supernova remnants, pulsars: individual: PSR J1957+2831 LAT PSR J1954+2836 LAT PSR J1958+2846}, doi = {10.1088/0004-637X/725/2/1629}, url = {http://adsabs.harvard.edu/abs/2010ApJ...725.1629A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Camara, M. and Carmona, E. and Carosi, A. and Colin, P. and Contreras, J.~L. and Cortina, J. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Gaug, M. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and Krause, J. and La Barbera, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paoletti, R. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and Rissi, M. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Vankov, H. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} }