Research Note

Observations of the magnetars 4U 0142+61 and 1E 2259+586 with the MAGIC telescopes^⋆

¹ IFAE, Edifici Cn., Campus UAB, 08193 Bellaterra, Spain
² INAF National Institute for Astrophysics, 00136 Rome, Italy
³ Università di Siena, and INFN Pisa, 53100 Siena, Italy
⁴ Universidad Complutense, 28040 Madrid, Spain
⁵ Max-Planck-Institut für Physik, 80805 München, Germany
⁶ Inst. de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
⁷ University of Łódź, 90236 Lodz, Poland
⁸ Depto. de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Spain
⁹ Deutsches Elektronen-Synchrotron (DESY), 15738 Zeuthen, Germany
¹⁰ ETH Zurich, 8093 Zurich, Switzerland
¹¹ Universität Würzburg, 97074 Würzburg, Germany
¹² Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, 28040 Madrid, Spain
¹³ Università di Udine, and INFN Trieste, 33100 Udine, Italy
¹⁴ Institut de Ciències de l’Espai (IEEC-CSIC), 08193 Bellaterra, Spain
e-mail: hadasch@ieec.uab.es
¹⁵ Technische Universität Dortmund, 44221 Dortmund, Germany
¹⁶ Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, 10000 Zagreb, Croatia
¹⁷ Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
¹⁸ Tuorla Observatory, University of Turku, 21500 Piikkiö, Finland
¹⁹ Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan
²⁰ Inst. for Nucl. Research and Nucl. Energy, 1784 Sofia, Bulgaria
²¹ Universitat de Barcelona (ICC/IEEC), 08028 Barcelona, Spain
²² Università di Padova and INFN, 35131 Padova, Italy
²³ INAF/Osservatorio Astronomico and INFN, 34143 Trieste, Italy
²⁴ Università dell’Insubria, Como, 22100 Como, Italy
²⁵ Inst. de Astrofísica de Andalucía (CSIC), 18080 Granada, Spain
²⁶ Università di Pisa, and INFN Pisa, 56126 Pisa, Italy
²⁷ ICREA, 08010 Barcelona, Spain
²⁸ Now at: Institut für Experimentalphysik, Universität Hamburg, Germany
²⁹ Now at : École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
³⁰ Supported by INFN Padova  
³¹ Now at: KIPAC, SLAC National Accelerator Laboratory, USA
³² Now at : DESY, Zeuthen, Germany
³³ Now at: Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Finland

Received: 22 August 2012
Accepted: 25 October 2012

Abstract

Context. Magnetars are an extreme, highly magnetized class of isolated neutron stars whose large X-ray luminosity is believed to be driven by their high magnetic field.

Aims. We study for the first time the possible very high energy γ-ray emission above 100 GeV from magnetars, observing the sources 4U 0142+61 and 1E 2259+586.

Methods. We observed the two sources with atmospheric Cherenkov telescopes in the very high energy range (E > 100 GeV). 4U 0142+61 was observed with the MAGIC I telescope in 2008 for about 25 h and 1E 2259+586 was observed with the MAGIC stereoscopic system in 2010 for about 14 h. The data were analyzed with the standard MAGIC analysis software.

Results. Neither magnetar was detected. Upper limits to the differential and integral flux above 200 GeV were computed using the Rolke algorithm. We obtain integral upper limits to the flux of 1.52 × 10^-12 cm^-2 s^-1 and 2.7 × 10^-12 cm^-2 s^-1 with a confidence level of 95% for 4U 0142+61 and 1E 2259+586, respectively. The resulting differential upper limits are presented together with X-ray data and upper limits in the GeV energy range.