Special Astronomy & Astrophysics Seminar: Observing black holes on horizon scales: from still images to black hole cinema

Zoom: https://tau-ac-il.zoom.us/j/87185167411?pwd=FpTUyIgXaOturzOFSetA6pPVYQilen.1

Abstract:

Black holes are cosmic objects so small and dense, that nothing, not even light can escape their gravitational pull.  Until recently, no one had ever seen what a black hole actually looked like.  Einstein's theories predict that a distant observer should see a ring of light encircling the black hole, which forms when radiation emitted by infalling hot gas is lensed by the extreme gravity near the event horizon.  The Event Horizon Telescope (EHT) is a global array of radio dishes, linked together by a network of atomic clocks to form an Earth-sized virtual telescope that can resolve the nearest supermassive black holes where this ring feature may be measured. The EHT has now successfully imaged the 6.5 billion solar mass black hole at the center of galaxy M87, and the 4 million solar mass black hole at the center of the Milky Way - both objects exhibiting the predicted strong gravitational lensing that confirms the theory of General Relativity at the boundary of a black hole.  Subsequent observations have revealed ordered magnetic fields on horizon scales with implications on how black holes launch relativistic jets of material.  This talk will cover how this was accomplished, details of the first results, as well as future directions.

Seminar Organizer: Dr. Jonathan Stern