The X-ray universe at microarsec resolution: the power and promise of X-ray interferometry

The spectacular image of a supermassive black hole `shadow’ taken by the Event Horizon Telescope last year highlights the potential of being able to resolve microarcsecond scale structures in astrophysical sources.  Given the ~Angstrom scale of X-ray wavelengths, similar resolutions are theoretically possible with only a 1 m diameter telescope, which could be accommodated on a single spacecraft. Conventional X-ray imaging capability remains far from from this goal however.

In this talk I will explore the possibility, recently proposed to ESA’s Voyage 2050 program, of developing X-ray interferometry to break the resolution barrier in the X-rays, starting from X-ray fringes which have already been observed in the lab and examining what would be required for an X-ray interferometric space observatory, from the possibilities with single spacecraft to formation flyers which could push to sub-microarcsecond resolution. Such revolutionary observatories would enable detailed imaging-spectroscopy of stellar coronae and transiting exoplanets within ~100 pc, direct observation of X-ray binary orbits, supermassive black hole accretion flows and event horizons, and imaging of luminous transients and binary supermassive black holes across the observable universe.