DETECTION OF VHE {gamma}-RAYS FROM HESS J0632+057 DURING THE 2011 FEBRUARY X-RAY OUTBURST WITH THE MAGIC TELESCOPES

Journal Article · Fri Jul 20 00:00:00 EDT 2012 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/754/1/L10· OSTI ID:22047657

Aleksic, J; Blanch, O ^[1]; Alvarez, E A; Asensio, M; Barrio, J A ^[2]; Antonelli, L A; Bonnoli, G ^[3]; Antoranz, P ^[4]; Backes, M ^[5]; Barres de Almeida, U; Bock, R K; Borla Tridon, D ^[6]; Bastieri, D ^[7]; Becerra Gonzalez, J; Berger, K ^[8]; Bednarek, W ^[9]; Bernardini, E ^[10]; Biland, A; Boller, A ^[11]; Bosch-Ramon, V ^[12] ; others, and

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1. IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra (Spain)
2. Grupo de Fisica Altas Energias, Universidad Complutense, E-28040 Madrid (Spain)
3. INAF National Institute for Astrophysics, I-00136 Rome (Italy)
4. Dipartimento di Fisica, Universita di Siena and INFN Pisa, I-53100 Siena (Italy)
5. Technische Universitaet Dortmund, D-44221 Dortmund (Germany)
6. Max-Planck-Institut fuer Physik, D-80805 Muenchen (Germany)
7. Dipartimento di Fisica, Universita di Padova and INFN, I-35131 Padova (Italy)
8. Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain)
9. Department of Astrophysics, University of Lodz, PL-90236 Lodz (Poland)
10. Deutsches Elektronen-Synchrotron (DESY), D-15738 Zeuthen (Germany)
11. ETH Zurich, CH-8093 Zurich (Switzerland)
12. Facultat de Fisica, Universitat de Barcelona (ICC/IEEC), E-08028 Barcelona (Spain)

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

• OSTI ID: 22047657
• Journal Information: Astrophysical Journal Letters, Vol. 754, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTROPHYSICS
BINARY STARS
COMPARATIVE EVALUATIONS
COSMIC GAMMA SOURCES
GAMMA ASTRONOMY
GAMMA DETECTION
GAMMA RADIATION
GEV RANGE
ORBITS
PHOTON EMISSION
STARS
X RADIATION
X-RAY DETECTION