Thursday, October 17, 2019, 16:00
WHGA Auditorium
Heino Falcke, Radboud University Nijmegen
Abstract:
One of the most fundamental predictions of general relativity are black
holes. Their defining feature is the event horizon, the surface that
even light cannot escape. When illuminated by ambient light, the event
horizon of black holes will cast a dark shadow on the emitting region
that is detectable under certain circumstances with global
interferometers operating at mm- and submm-wavelengths. Recently the
Event Horizon Telescope has detected this shadow feature in the radio
galaxy M87, providing a first glimpse at scales surrounding the event
horizon. Models invoking general relativity and magnetized plasma
hydrodynamics are able to reproduce the appearance of the shadow and of
the powerful jet launched at these scales. This provides strong support
for the existence of supermassive black holes in the universe and sheds
light on how they work. To improve the imaging quality further more
telescopes should be added to the array, in particular in Africa. The
more distant future will belong to higher frequencies and space-based
interferometry. The talk will review the latest results of the Event
Horizon Telescope, its scientific implications and future expansions of
the array.