The High Energy X-ray Probe (HEX-P): Resolved X-ray Populations in Extragalactic Environments

HEX-P is a probe-class mission concept that will combine high spatial resolution X-ray imaging (<10 arcsec FWHM) and broad spectral coverage (0.1-150 keV) with an effective area far superior to current facilities (including XMM-Newton and NuSTAR) to enable revolutionary new insights into a variety of important astrophysical problems. We will present simulations of HEX-P observations of a variety of extragalactic environments (e.g., normal, starburst, and passive galaxies) to demonstrate the power of the HEX-P observatory. We will show that HEX-P will (1) provide unique information about X-ray binary populations in external galaxies, including accretor demographics (black hole and neutron stars), accretion state distributions, and cadences of state transitions; (2) detect and characterize, for the first time, inverse Compton emission associated with particle accelerations in starburst environments; and (3) put into clear context the contributions from X-ray emitting populations to both ionizing surrounding interstellar mediums in low-metallicity galaxies and heating the intergalactic medium in the z > 8 Universe. More information on HEX-P, including the full team list, is available at http://hexp.org.