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

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. Study for the first time the possible very high energy -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∼25 h and 1E 2259+586 was observed with the MAGIC stereoscopic system in 2010 for∼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 t he 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 dat a and upper limits in the GeV energy range.