@article {2010A\&A...524A..77A, title = {{Search for an extended VHE {$\gamma$}-ray emission from Mrk 421 and Mrk 501 with the MAGIC Telescope}}, journal = {Astronomy and Astrophysics}, volume = {524}, year = {2010}, month = {dec}, pages = {A77}, abstract = {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 obtain upper limits on the extended emission around the Mrk 421 (Mrk 501) on the level of {\l}t}5\% ({\l}t}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.}, keywords = {galaxies: active, {$\gamma$}-rays: galaxies}, doi = {10.1051/0004-6361/201014747}, url = {http://adsabs.harvard.edu/abs/2010A\%26A...524A..77A}, 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 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 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. 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 Neronov, A. and Semikoz, D.~V.} } @article {2010ApJ...710..828A, title = {{Search for Very High Energy Gamma-ray Emission from Pulsar-Pulsar Wind Nebula Systems with the MAGIC Telescope}}, journal = {The Astrophysical Journal}, volume = {710}, year = {2010}, month = {feb}, pages = {828-835}, abstract = {The MAGIC collaboration has searched for high-energy gamma-ray emission of some of the most promising pulsar candidates above an energy threshold of 50 GeV, an energy not reachable up to now by other ground-based instruments. Neither pulsed nor steady gamma-ray emission has been observed at energies of 100 GeV from the classical radio pulsars PSR J0205+6449 and PSR J2229+6114 (and their nebulae 3C58 and Boomerang, respectively) and the millisecond pulsar PSR J0218+4232. Here, we present the flux upper limits for these sources and discuss their implications in the context of current model predictions.}, keywords = {gamma rays: stars, methods: observational, pulsars: individual: PSR J0205+6449 PSR J2229+6114 PSR J0218+4232, telescopes}, doi = {10.1088/0004-637X/710/1/828}, url = {http://adsabs.harvard.edu/abs/2010ApJ...710..828A}, author = {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 Berger, a.~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 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 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 Robert, A. 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 Stark, L.~S. 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 Cognard, I.} } @article {2010A\&A...515A..76A, title = {{Simultaneous multi-frequency observation of the unknown redshift blazar PG 1553+113 in March-April 2008}}, journal = {Astronomy and Astrophysics}, volume = {515}, year = {2010}, month = {jun}, pages = {A76}, abstract = {The blazar PG 1553+113 is a well known TeV {$\gamma$}-ray emitter. In this paper we determine its spectral energy distribution through simultaneous multi-frequency data to study its emission processes. An extensive campaign was carried out between March and April 2008, where optical, X-ray, high-energy (HE) {$\gamma$}-ray, and very-high-energy (VHE) {$\gamma$}-ray data were obtained with the KVA, Abastumani, REM, RossiXTE/ASM, AGILE and MAGIC telescopes, respectively. We combine the data to derive the source{\textquoteright}s spectral energy distribution and interpret its double-peaked shape within the framework of a synchrotron self-Compton model.}, keywords = {BL Lacertae objects: individual: PG 1553+113, galaxies: active, gamma rays: galaxies, X-rays: galaxies}, doi = {10.1051/0004-6361/200913607}, url = {http://adsabs.harvard.edu/abs/2010A\%26A...515A..76A}, 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 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 Pian, E. and Bianchin, V. and D{\textquoteright}Ammando, F. and Di Cocco, G. and Fugazza, D. and Ghisellini, G. and Kurtanidze, O.~M. and Raiteri, C.~M. and Tosti, G. and Treves, A. and Vercellone, S. and Villata, M. and MAGIC Collaboration} }