Observations of the Crab pulsar between 25 GeV and 100 GeV with the MAGIC I telescope

📝 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 {\it Fermi} Large Area Telescope ({\it 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 $-3.1 \pm 1.0_{stat} \pm 0.3_{syst}$ and $-3.5 \pm 0.5_{stat} \pm 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 $-0.009 \pm 0.007$ and $0.393 \pm 0.009 $, while the full widths at half maximum are $0.025 \pm 0.008$ and $0.053 \pm 0.015 $, respectively.

💡 Analysis

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 {\it Fermi} Large Area Telescope ({\it 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 $-3.1 \pm 1.0_{stat} \pm 0.3_{syst}$ and $-3.5 \pm 0.5_{stat} \pm 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 $-0.009 \pm 0.007$ and $0.393 \pm 0.009 $, while the full widths at half maximum are $0.025 \pm 0.008$ and $0.053 \pm 0.015 $, respectively.

📄 Content

arXiv:1108.5391v3 [astro-ph.HE] 8 Nov 2011 Draft version October 29, 2018 Preprint typeset using LATEX style emulateapj v. 04/20/08 OBSERVATIONS OF THE CRAB PULSAR BETWEEN 25 AND 100 GEV WITH THE MAGIC I TELESCOPE J. Aleksi´c1, E. A. Alvarez2, L. A. Antonelli3, P. Antoranz4, M. Asensio2, M. Backes5, J. A. Barrio2, D. Bastieri6, J. Becerra Gonz´alez7,8, W. Bednarek9, A. Berdyugin10, K. Berger7,8, E. Bernardini11, A. Biland12, O. Blanch1, R. K. Bock13, A. Boller12, G. Bonnoli3, D. Borla Tridon13, I. Braun12, T. Bretz14,29, A. Ca˜nellas15, E. Carmona13, A. Carosi3, P. Colin13, E. Colombo7, J. L. Contreras2, J. Cortina1, L. Cossio16, S. Covino3, F. Dazzi16,30, A. De Angelis16, G. De Caneva11, E. De Cea del Pozo17, B. De Lotto16, C. Delgado Mendez7,31, A. Diago Ortega7,8, M. Doert5, A. Dom´ınguez18, D. Dominis Prester19, D. Dorner12, M. Doro20, D. Eisenacher14, D. Elsaesser14, D. Ferenc19, M. V. Fonseca2, L. Font20, C. Fruck13, R. J. Garc´ıa L´opez7,8, M. Garczarczyk7, D. Garrido20, G. Giavitto1, N. Godinovi´c19, D. Hadasch17, D. H¨afner13, A. Herrero7,8, D. Hildebrand12, D. H¨ohne-M¨onch14, J. Hose13, D. Hrupec19, T. Jogler13, H. Kellermann13, S. Klepser1, T. Kr¨ahenb¨uhl12, J. Krause13, J. Kushida13, A. La Barbera3, D. Lelas19, E. Leonardo4, E. Lindfors10, S. Lombardi6, M. L´opez2, A. L´opez-Oramas1, E. Lorenz12,13, M. Makariev21, G. Maneva21, N. Mankuzhiyil16, K. Mannheim14, L. Maraschi3, B. Marcote15, M. Mariotti6, M. Mart´ınez1, D. Mazin1,13, M. Meucci4, J. M. Miranda4, R. Mirzoyan13, J. Mold´on15, A. Moralejo1, P. Munar-Adrover15, D. Nieto2, K. Nilsson10,32, R. Orito13, N. Otte22, I. Oya2, D. Paneque13, R. Paoletti4, S. Pardo2, J. M. Paredes15, S. Partini4, M. A. Perez-Torres1, M. Persic16,23, L. Peruzzo6, M. Pilia24, J. Pochon7, F. Prada18, P. G. Prada Moroni25, E. Prandini6, I. Puerto Gimenez7, I. Puljak19, I. Reichardt1, R. Reinthal10, W. Rhode5, M. Rib´o15, J. Rico26,1, M. Rissi27, S. R¨ugamer14, A. Saggion6, K. Saito13, T. Y. Saito13,, M. Salvati3, K. Satalecka2, V. Scalzotto6, V. Scapin2, C. Schultz6, T. Schweizer13, M. Shayduk13, S. N. Shore25, A. Sillanp¨a¨a10, J. Sitarek9, I. Snidaric19, D. Sobczynska9, F. Spanier14, S. Spiro3, V. Stamatescu1, A. Stamerra4, B. Steinke13, J. Storz14, N. Strah5, T. Suri´c19, L. Takalo10, H. Takami13, F. Tavecchio3, P. Temnikov21, T. Terzi´c19, D. Tescaro25, M. Teshima13, O. Tibolla14, D. F. Torres26,17, A. Treves24, M. Uellenbeck5, H. Vankov21, P. Vogler12, R. M. Wagner13, Q. Weitzel12, V. Zabalza15, F. Zandanel18, R. Zanin1 and K. Hirotani28, Draft version October 29, 2018 ABSTRACT We report on the observation of γ-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 cutoffspectrum 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±1.0stat±0.3syst and −3.5±0.5stat±0.3syst, 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. Subject headings: Gamma rays: stars — pulsars: individual (Crab pulsar, PSR B0531+21) 1 IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain 2 Universidad Complutense, E-28040 Madrid, Spain 3 INAF National Institute for Astrophysics, I-00136 Rome, Italy 4 Universita di Siena, and INFN Pisa, I-53100 Siena, Italy 5 Technische Universit¨at Dortmund, D-44221 Dortmund, Ger- many 6 Universita di Padova and INFN, I-35131 Padova, Italy 7 Inst. de Astrof´ısica de Canarias, E-38200 La Laguna, Tenerife, Spain 8 Depto. de Astrof´ısica, Universidad de La Laguna, E-38206 La Laguna, Spain 9 University of L´od´z, PL-90236 Lodz, Poland 10 Tuorla Observatory, University of Turku, FI-21500 Piikki¨o, Finland 11 Deutsches Elektronen-Synchrotron (DESY), D-15738 Zeuthen, Germany 12 ETH Zurich, CH-8093 Zurich, Switzerland 13 Max-Planck-Institut f¨ur Physik, D-80805 M¨unchen, Germany 14 Universit¨at W¨urzburg, D-97074 W¨urzburg, Germany 15 Universitat de Barcelona (ICC/IEEC), E-08028 Barcelona, Spain 16 Universita di Udine, and INFN Trieste, I-33100 Udine, Italy 17 Institut de Ciencies de l’Espai (IEEC-CSIC), E-08193 Bel- laterra, Spain 18 Inst. de Astrof´ısica de Andaluc´ıa (CSIC), E-18080 Granada, Spain 19 Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of

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