Public Talk

Date: Monday, January 28, 2019
Time: 10:30 am - 11: 15 am
Speaker:  Prof. Dr. Malcolm A. H. MacCallum
Institution: Queen Mary University of London, UK
Title: Black holes and neutron stars

Abstract: When stars run out of nuclear fuel they may form "white dwarfs" or "neutron stars". These possibilities only work for fairly small stars. Large stars have no way to hold up against their own gravity and collapse to black holes, from which no light escapes.  Neutron stars have been found as "pulsars" since the 1960s. Evidence for black holes was harder to find but X-ray binaries showed stellar mass black holes and galactic centers showed supermassive black holes. The masses of the latter are correlated with properties of their host galaxies. In 2016 a first black hole merger was observed by gravitational wave detectors: we have now observed 10 such. We have also observed one neutron star merger, not only with gravitational waves but in all astronomical wavebands from radio to gamma rays. These observations have surprising implications.