Title: Multiwavelength Population Studies of High Mass X-ray Binaries in Nearby Galaxies
Margaret Lazzarini(University of Washington)
High mass X-ray binaries (HMXBs) are systems that contain a compact object that accretes mass from its massive stellar companion. These unique endpoints offer exceptional laboratories for testing models of massive star binary evolution, and massive stellar evolution as a whole, given the high binary fraction of massive stars. The HMXB phase is a key observable window in the evolution of massive binary stars, a phase of critical importance given their role as progenitors of compact object mergers detectable with gravitational waves. Recently, HMXBs have emerged as another important source of feedback and as a likely contributor to cosmic reionization. Population studies of HMXBs in nearby galaxies constrain models of their formation and evolution by tying their X-ray and optical properties to their parent stellar populations. In this talk I will present population studies of HMXBs in nearby galaxies focusing on work in M31 and the SMC and highlighting ongoing work in M33. These studies include characterizing the secondary stars of HMXB candidates with multi-wavelength observations, constraining the ages of the HMXB candidate systems from their surrounding stellar populations, and applying hard X-ray information from NuSTAR to infer the likely compact object type. Finally, I will touch on ongoing work with binary population synthesis models to reproduce the population demographics we observe in order to better constrain massive binary stellar evolution.