Ciriaco Goddi
University of Leiden, Netherlands

Abstract
One of the most fundamental predictions of general relativity (GR) are black holes. Their defining feature is the event horizon, the surface that even light cannot escape. So far, we have never seen the event horizon, but this is about to change. Advanced computer simulations make clear predictions about the appearance of the black hole shadow, which is a lensed image of the event horizon. This shadow can now be resolved by very long baseline interferometry (VLBI) experiments at mm wavelengths, for the very first time, in at least two objects: the supermassive black hole in the center of our own Milky Way, Sgr A*, and the radio galaxy M87. This may allows us for the first time to test GR on an event horizon scale with imaging techniques.
The first joint VLBI observations that include ALMA as a phased array with other telescopes worldwide were conducted in April 2017, both at 3 mm with the Global mm VLBI Array (GMVA) and at 1.3 mm with the Event Horizon Telescope (EHT), and a second observing campaign was conducted in April this year. The talk will give an overview of the ongoing research to image and simulate black holes, as well as of plans for future expansions.

2018 June 28, 15:00

IA/U.Lisboa
Observatório Astronómico de Lisboa (Seminar room)
Tapada da Ajuda, 1349-018 Lisboa