Concerning the occurrence of bow shocks around high-mass X-ray binaries

Abstract

Context. We investigate the occurrence of stellar bow shocks around high-mass X-ray binaries (HMXBs) in the Galaxy. Aims. We seek to conduct a survey of HMXBs in the mid-infrared to search for the presence of bow shocks around these objects. Methods. Telescopes operating in the mid-infrared, such as the Spitzer Space Telescope or Wide-field Infrared Survey Explorer (WISE), are potent tools for searching for the stellar bow shocks. We used the available archival data from these telescopes to search for bow shock candidates around the confirmed and candidate HMXBs in the Galaxy. Results. We detected extended mid-infrared structures around several surveyed confirmed and candidate HMXBs. Two of these structures, associated with Vela X-1 and 4U 1907+09, are genuine bow shocks that have been studied previously. However, there are no new unambiguous bow shocks among the rest of the objects. The paucity of bow shocks around HMXBs suggests that the majority of these systems still reside within hot, low-density bubbles around their parent star clusters or associations. This also implies that the dynamical ejection of massive binaries is apparently less efficient than the ejections caused by the supernova explosions inside a binary.