http://arxiv.org/abs/2212.10146
Colliding-Wind Binaries (CWBs) constitute an emerging class of gamma-ray sources powered by strong, dense winds in massive stellar systems. The most powerful of them are those binaries hosting a Wolf-Rayet (WR) star. Following the recent discovery of Apep – the closest known Galactic WR-WR binary – we discuss here the non-detection of its putative high-energy emission by the Fermi Large Area Telescope (Fermi-LAT). The limits reported in the GeV regime can be used to set a lower limit on the magnetic field pressure density within the shocked wind-collision region (WCR), and exclude Apep as a bright gamma-ray emitting binary. Given that this WR-WR system is the most luminous CWB identified until now at radio wavelengths, this result proves unambiguously that non-thermal synchrotron emission is not a suitable identifier for the subset of gamma-ray emitters in this class of particle accelerators. Rather, Apep could be an interesting case of study for magnetic field amplification in shocked stellar winds.
G. Martí-Devesa, O. Reimer and A. Reimer
Wed, 21 Dec 22
37/81
Comments: 4 pages, 2 figures. Accepted as a Letter in Astronomy and Astrophysics
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