Searching for Exoplanets orbiting X-ray Binaries via Direct Imaging

Myriam Prasow-Émond ( Université de Montréal )

X-ray binaries, composed of a compact object (stellar-mass black hole, neutron star, or white dwarf) accreting material from a donor star, are fantastic laboratories for studying astronomical objects and phenomena under extreme conditions. Although the study of these systems has led to major breakthroughs in high-energy astrophysics, their circumbinary environment at ∼100-5000 astronomical units (AU) scales is yet to be studied in detail. In fact, it remains unclear how the accretion onto the compact objects or the explosions giving rise to the compact objects interact with their immediate surroundings. In this project, we conducted a new and explorative, yet innovative, study by applying direct and high-contrast imaging techniques on a sample of a dozen X-ray binaries using the vortex coronagraph on Keck/NIRC2. This allowed us, for the very first time, to seek exoplanets, or even brown dwarfs, companion stars, and protoplanetary disks, in these extreme environments. In this talk, we present the key results from this campaign: the discovery of several candidate companions ranging from planetary to stellar masses. In addition to extending our comprehension of how companions can form and survive in such systems, this project could allow us to completely redefine our understanding of X-ray binaries.