Speaker: Alejo Martinez-Sansigre
Location: Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London
Every massive galaxy is believed to harbour a supermassive black hole in its centre. These can grow by accretion or by mergers, and these processes will leave different imprints in the spin history of the supermassive black holes. I will discuss several different approaches to estimating the cosmic spin of supermassive black holes, using the mean radiative efficiency of quasars, but more informatively by using radio observations. These radio observations trace the jets produced by supermassive black holes, and using recent theoretical models we have shown that black hole spin can explain the varying jet powers observed amongst active galactic nuclei, as well as the radio luminosity function. We can therefore use the radio observations to infer the cosmic spin history of the most massive black holes, and I will discuss the implications for the processes by which they grow.