A LUMINOUS GAMMA-RAY BINARY IN THE LARGE MAGELLANIC CLOUD
- University of Maryland, Baltimore County, and X-ray Astrophysics Laboratory, Code 662 NASA Goddard Space Flight Center, Greenbelt Rd., MD 20771 (United States)
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)
- University of Southampton, School of Physics and Astronomy, Southampton SO17 1BJ (United Kingdom)
- NASA Postdoctoral Program, and Astroparticle Physics Laboratory, Code 661 NASA Goddard Space Flight Center, Greenbelt Rd., MD 20771 (United States)
- Institut de Planétologie et d’Astrophysique de Grenoble, Univ. Grenoble Alpes, CNRS, F-38000 Grenoble (France)
- Commonwealth Scientific and Industrial Research Organisation Astronomy and Space Science, P.O. Box 76, Epping, New South Wales 1710 (Australia)
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, F-31028 Toulouse cedex 4 (France)
- Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa)
- Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland)
Gamma-ray binaries consist of a neutron star or a black hole interacting with a normal star to produce gamma-ray emission that dominates the radiative output of the system. Only a handful of such systems have been previously discovered, all within our Galaxy. Here, we report the discovery of a luminous gamma-ray binary in the Large Magellanic Cloud, found with the Fermi Large Area Telescope (LAT), from a search for periodic modulation in all sources in the third Fermi LAT catalog. This is the first such system to be found outside the Milky Way. The system has an orbital period of 10.3 days, and is associated with a massive O5III star located in the supernova remnant DEM L241, previously identified as the candidate high-mass X-ray binary (HMXB) CXOU J053600.0–673507. X-ray and radio emission are also modulated on the 10.3 day period, but are in anti-phase with the gamma-ray modulation. Optical radial velocity measurements suggest that the system contains a neutron star. The source is significantly more luminous than similar sources in the Milky Way, at radio, optical, X-ray, and gamma-ray wavelengths. The detection of this extra-galactic system, but no new Galactic systems, raises the possibility that the predicted number of gamma-ray binaries in our Galaxy has been overestimated, and that HMXBs may be born containing relatively slowly rotating neutron stars.
- OSTI ID:
- 22667382
- Journal Information:
- Astrophysical Journal, Vol. 829, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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