Detection of VHE γ-rays from HESS J0632+057 during the 2011 february X-ray outburst with the magic telescopes

J. Aleksić, E. A. Alvarez, L. A. Antonelli, P. Antoranz, M. Asensio, M. Backes, U. Barres De Almeida, J. A. Barrio, D. Bastieri, J. Becerra González, W. Bednarek, K. Berger, E. Bernardini, A. Biland, O. Blanch, R. K. Bock, A. Boller, G. Bonnoli, D. Borla Tridon, V. Bosch-RamonT. Bretz, A. Cañellas, E. Carmona, A. Carosi, P. Colin, E. Colombo, J. L. Contreras, J. Cortina, L. Cossio, S. Covino, P. Da Vela, F. Dazzi, A. De Angelis, G. De Caneva, E. De Cea Del Pozo, B. De Lotto, C. Delgado Mendez, A. Diago Ortega, M. Doert, A. Domínguez, D. Dominis Prester, D. Dorner, M. Doro, D. Eisenacher, D. Elsaesser, D. Ferenc, M. V. Fonseca, L. Font, C. Fruck, R. J. García López, M. Garczarczyk, D. Garrido Terrats, G. Giavitto, N. Godinović, A. González Muñoz, S. R. Gozzini, D. Hadasch, D. Häfner, A. Herrero, D. Hildebrand, J. Hose, D. Hrupec, B. Huber, F. Jankowski, T. Jogler, V. Kadenius, H. Kellermann, S. Klepser, T. Krähenbühl, J. Krause, A. La Barbera, D. Lelas, E. Leonardo, N. Lewandowska, E. Lindfors, S. Lombardi, M. López, R. López-Coto, A. López-Oramas, E. Lorenz, M. Makariev, G. Maneva, N. Mankuzhiyil, K. Mannheim, L. Maraschi, M. Mariotti, M. Martínez, D. Mazin, M. Meucci, J. M. Miranda, R. Mirzoyan, J. Moldón, A. Moralejo, P. Munar-Adrover, A. Niedzwiecki, D. Nieto, K. Nilsson, N. Nowak, R. Orito, S. Paiano

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Abstract

The very high energy (VHE) γ-ray source HESS J0632+057 has recently been confirmed to be a γ-ray binary. The optical counterpart is the Be star MWC 148, and a compact object of unknown nature orbits it every 321days with a high eccentricity of 0.8. We monitored HESS J0632+057 with the stereoscopic MAGIC telescopes from 2010 October to 2011 March and detected significant VHE γ-ray emission during 2011 February, when the system exhibited an X-ray outburst. We find no γ-ray signal in the other observation periods when the system did not show increased X-ray flux. Thus, HESS J0632+057 exhibits γ-ray variability on timescales of the order of one to two months possibly linked to the X-ray outburst that takes place about 100days after the periastron passage. Furthermore, our measurements provide for the first time the γ-ray spectrum down to about 140GeV and indicate no turnover of the spectrum at low energies. We compare the properties of HESS J0632+057 with the similar γ-ray binary LS I +61°303 and discuss the possible origin of the multi-wavelength emission of the source. © 2012. The American Astronomical Society. All rights reserved.
Original languageEnglish
Article numberL10
JournalAstrophysical Journal Letters
Volume754
Issue number1
DOIs
Publication statusPublished - 20 Jul 2012

Keywords

  • binaries: general
  • gamma rays: general
  • stars: individual (MWC 148)
  • X-rays: binaries
  • X-rays: individual (HESS J0632+057)

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