Speaker
Description
Contributed talk
Abstract:
"High-frequency very-long-baseline Interferometric (VLBI) observations of the Galactic Center supermassive black hole, Sagittarius A (Sgr A) have sufficient angular resolution to probe black hole accretion and outflow on event-horizon scales. We present the first unscattered image of Sgr A taken at 86 GHz (3.5-mm) using the Global Millimeter VLBI Array (GMVA) joined for the first time by ALMA operating as a phased array in April 2017. The network reaches an angular resolution of 87 micro-arcseconds, improving upon previous experiments by a factor of two, and revealing a nearly isotropic intrinsic source. I will discuss the consequences for underlying accretion and emission models of Sgr A, as well as new constraints on the properties of interstellar scattering using baselines to ALMA."
