Multi-messenger opportunities with the X-ray and UV Capabilities of STAR-X

The X-ray and UV instruments on STAR-X are uniquely designed to study three powerful components of the rapidly-varying “fast” Universe: supernova shock breakouts, binary neutron star mergers, and stellar flares in planet-hosting systems. I will discuss how STAR-X will (1) determine the progenitors and mass loss histories of H-poor, core-collapse SNe, (2) reveal the angular structure of newly-formed relativistic jets and uncover the origin of the early blue-UV emission from ≥10 BNS counterparts, and (3) trace the cumulative XUV irradiance incident on exoplanet atmospheres around low-mass, magnetically active stars. I’ll also discuss our plans to target X-ray and UV transients, including extragalactic fast X-ray transients, black hole binary outbursts, Type Ia SNe, and SMBH-related flares, thus opening multiple new transient discovery domains. STAR-X is designed to conduct time-domain surveys and to respond rapidly to transient events discovered by other observatories such as LIGO, Rubin/LSST, Roman/WFIRST, and SKA. The observing plan also contains 1.8 Ms to support a Community Targets of Opportunity program, e.g., to search for counterparts to new multi-wavelength and multi-messenger discoveries, including fast radio bursts and high-energy neutrino sources from IceCube. STAR-X is thus a timely response to Astro2020’s recommendation for a space-based, sustaining time-domain and multi-messenger program and we welcome community input on how to maximize STAR-X science returns. More information on STAR-X, including the full team list, is available at http://star-x.xraydeep.org.