OBSERVATIONS OF THE CRAB PULSAR BETWEEN 25 AND 100 GeV WITH THE MAGIC I TELESCOPE


Authors:
Aleksic, J (Aleksic, J.)2; Alvarez, EA (Alvarez, E. A.)3; Antonelli, LA (Antonelli, L. A.)4; Antoranz, P (Antoranz, P.)5,6; Asensio, M (Asensio, M.)3; Backes, M (Backes, M.)7; Barrio, JA (Barrio, J. A.)3; Bastieri, D (Bastieri, D.)8,9; Gonzalez, JB (Becerra Gonzalez, J.)10,11; Bednarek, W (Bednarek, W.)12; Berdyugin, A (Berdyugin, A.)13,8; Berger, K (Berger, K.)10,11; Bernardini, E (Bernardini, E.)14; Biland, A (Biland, A.)15; Blanch, O (Blanch, O.)2; Bock, RK (Bock, R. K.)1; Boller, A (Boller, A.)15; Bonnoli, G (Bonnoli, G.)4; Tridon, DB (Tridon, D. Borla)1; Braun, I (Braun, I.)15; Bretz, T (Bretz, T.)16; Canellas, A (Canellas, A.)17; Carmona, E (Carmona, E.)1; Carosi, A (Carosi, A.)4; Colin, P (Colin, P.)1; Colombo, E (Colombo, E.)10; Contreras, JL (Contreras, J. L.)3; Cortina, J (Cortina, J.)2; Cossio, L (Cossio, L.)18,19; Covino, S (Covino, S.)4; Dazzi, F (Dazzi, F.)18,19; De Angelis, A (De Angelis, A.)18,19; De Caneva, G (De Caneva, G.)14; del Pozo, ED (De Cea del Pozo, E.)20; De Lotto, B (De Lotto, B.)18,19; Mendez, CD (Delgado Mendez, C.)10; Ortega, AD (Diago Ortega, A.)10,11; Doert, M (Doert, M.)7; Dominguez, A (Dominguez, A.)21; Prester, DD (Prester, D. Dominis)22,23; Dorner, D (Dorner, D.)15; Doro, M (Doro, M.)24; Eisenacher, D (Eisenacher, D.)16; Elsaesser, D (Elsaesser, D.)16; Ferenc, D (Ferenc, D.)22,23; Fonseca, MV (Fonseca, M. V.)3; Font, L (Font, L.)24; Fruck, C (Fruck, C.)1; Lopez, RJG (Garcia Lopez, R. J.)10,11; Garczarczyk, M (Garczarczyk, M.)10; Garrido, D (Garrido, D.)24; Giavitto, G (Giavitto, G.)2; Godinovic, N (Godinovic, N.)22,23; Hadasch, D (Hadasch, D.)20; Hafner, D (Haefner, D.)1; Herrero, A (Herrero, A.)10,11; Hildebrand, D (Hildebrand, D.)15; Hohne-Monch, D (Hoehne-Moench, D.)16; Hose, J (Hose, J.)1; Hrupec, D (Hrupec, D.)22,23; Jogler, T (Jogler, T.)1; Kellermann, H (Kellermann, H.)1; Klepser, S (Klepser, S.)2; Krahenbuhl, T (Kraehenbuehl, T.)15; Krause, J (Krause, J.)1; Kushida, J (Kushida, J.)1; La Barbera, A (La Barbera, A.)4; Lelas, D (Lelas, D.)22,23; Leonardo, E (Leonardo, E.)5,6; Lindfors, E (Lindfors, E.)13; Lombardi, S (Lombardi, S.)8,9; Lopez, M (Lopez, M.)3; Lopez-Oramas, A (Lopez-Oramas, A.)2; Lorenz, E (Lorenz, E.)1,15; Makariev, M (Makariev, M.)25; Maneva, G (Maneva, G.)25; Mankuzhiyil, N (Mankuzhiyil, N.)18,19; Mannheim, K (Mannheim, K.)16; Maraschi, L (Maraschi, L.)4; Marcote, B (Marcote, B.)17; Mariotti, M (Mariotti, M.)8,9; Martinez, M (Martinez, M.)2; Mazin, D (Mazin, D.)1,2; Meucci, M (Meucci, M.)5,6; Miranda, JM (Miranda, J. M.)5,6; Mirzoyan, R (Mirzoyan, R.)1; Moldon, J (Moldon, J.)17; Moralejo, A (Moralejo, A.)2; Munar-Adrover, P (Munar-Adrover, P.)17; Nieto, D (Nieto, D.)3; Nilsson, K (Nilsson, K.)13; Orito, R (Orito, R.)1; Otte, N (Otte, N.)26,27; Oya, I (Oya, I.)3; Paneque, D (Paneque, D.)1; Paoletti, R (Paoletti, R.)5,6; Pardo, S (Pardo, S.)3; Paredes, JM (Paredes, J. M.)17; Partini, S (Partini, S.)5,6; Perez-Torres, MA (Perez-Torres, M. A.)2; Persic, M (Persic, M.)18,19,28,29; Peruzzo, L (Peruzzo, L.)8,9; Pilia, M (Pilia, M.)30; Pochon, J (Pochon, J.)10; Prada, F (Prada, F.)21; Moroni, PGP (Moroni, P. G. Prada)31,32; Prandini, E (Prandini, E.)8,9; Gimenez, IP (Puerto Gimenez, I.)10; Puljak, I (Puljak, I.)22,23; Reichardt, I (Reichardt, I.)2; Reinthal, R (Reinthal, R.)13; Rhode, W (Rhode, W.)7; Ribo, M (Ribo, M.)17; Rico, J (Rico, J.)2,33; Rissi, M (Rissi, M.)34; Rugamer, S (Ruegamer, S.)16; Saggion, A (Saggion, A.)8,9; Saito, K (Saito, K.)1; Saito, TY (Saito, T. Y.)1; Salvati, M (Salvati, M.)4; Satalecka, K (Satalecka, K.)3; Scalzotto, V (Scalzotto, V.)8,9; Scapin, V (Scapin, V.)3; Schultz, C (Schultz, C.)8,9; Schweizer, T (Schweizer, T.)1; Shayduk, M (Shayduk, M.)1; Shore, SN (Shore, S. N.)31,32; Sillanpaa, A (Sillanpaa, A.)13; Sitarek, J (Sitarek, J.)12; Snidaric, I (Snidaric, I.)22,23; Sobczynska, D (Sobczynska, D.)12; Spanier, F (Spanier, F.)16; Spiro, S (Spiro, S.)4; Stamatescu, V (Stamatescu, V.)2; Stamerra, A (Stamerra, A.)5,6; Steinke, B (Steinke, B.)1; Storz, J (Storz, J.)16; Strah, N (Strah, N.)7; Suric, T (Suric, T.)22,23; Takalo, L (Takalo, L.)13; Takami, H (Takami, H.)1; Tavecchio, F (Tavecchio, F.)4; Temnikov, P (Temnikov, P.)25; Terzic, T (Terzic, T.)22,23; Tescaro, D (Tescaro, D.)31,32; Teshima, M (Teshima, M.)1; Tibolla, O (Tibolla, O.)16; Torres, DF (Torres, D. F.)20,33; Treves, A (Treves, A.)30; Uellenbeck, M (Uellenbeck, M.)7; Vankov, H (Vankov, H.)25; Vogler, P (Vogler, P.)15; Wagner, RM (Wagner, R. M.)1; Weitzel, Q (Weitzel, Q.)15; Zabalza, V (Zabalza, V.)17; Zandanel, F (Zandanel, F.)21; Zanin, R (Zanin, R.)2; Hirotani, K (Hirotani, K.)35

Abstract:
We report on the observation of gamma-rays above 25 GeV from the Crab pulsar (PSR B0532+ 21) using the MAGIC I telescope. Two data sets from observations during the winter period 2007/2008 and 2008/2009 are used. In order to discuss the spectral shape from 100 MeV to 100 GeV, one year of public Fermi Large Area Telescope (Fermi-LAT) data are also analyzed to complement the MAGIC data. The extrapolation of the exponential cutoff spectrum determined with the Fermi-LAT data is inconsistent with MAGIC measurements, which requires a modification of the standard pulsar emission models. In the energy region between 25 and 100 GeV, the emission in the P1 phase (from -0.06 to 0.04, location of the main pulse) and the P2 phase (from 0.32 to 0.43, location of the interpulse) can be described by power laws with spectral indices of -3.1 +/- 1.0(stat) +/- 0.3(syst) and -3.5 +/- 0.5(stat) +/- 0.3(syst), respectively. Assuming an asymmetric Lorentzian for the pulse shape, the peak positions of the main pulse and the interpulse are estimated to be at phases -0.009 +/- 0.007 and 0.393 +/- 0.009, while the full widths at half- maximum are 0.025 +/- 0.008 and 0.053 +/- 0.015, respectively.

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