X-ray interferometry: exciting science and feasible technology

Imagine a telescope with resolution so fine it can image the event horizon of a black hole in a quasar, resolve the disk of a star in another galaxy, or measure parallax to the Virgo Cluster. Such is the promise of X-ray interferometry. Because of the short wavelength of X-rays, interferometer baselines can be much shorter and more practical than systems in the visible. Intercontinental baseline interferometry now practiced in the radio can be matched with just a 10 cm baseline in the X-ray. With a 100 m baseline in space, an X-ray interferometer can resolve features finer than one micro-arc second. We believe we have found a practical approach to X-ray interferometry, and here discuss efforts to build and demonstrate a prototype X-ray interferometer with resolution near one milli-arcsecond. The prototype will demonstrate the feasibility of this technical path to the nano-arcsecond range