RSAA Colloquia / Seminars / Feast-of-Facts: Thursday, 07 July 2016, 11:00-12:00; Duffield Lecture Theatre

Martin Krause

"Extragalactic Jets"

Extragalactic jets originate from the immediate vicinity of supermassive black holes. They interact with their environment forming radio lobes with sufficient cross section to cause galaxy-wide effects. Studying the interaction of jets with their environment therefore promises insights into the surroundings of black holes, and effects on galaxy evolution. I will show simulation studies of the jet environment interaction. Comparison with observations allow us to constrain the conditions in the vicinity of the supermassive black holes. A particular, long-standing question is what the jets are made of, again related to processes in the immediate vicinity of black holes. For a Galactic jet source, Mikroquasar V404, we have detected positrons directly by their annihilation signature in MeV spectra with INTEGRAL, with implications for all black-hole jet systems. Our simulations also provide some insight into heating of the intracluster medium and effects of magnetic fields in and around radio lobes. In gas-rich galaxies, jets clear out gas in some parts of the galaxy, but overall lead to enhanced star formation due to the high pressure applied by the radio lobes. A signature of jet-induced stars is their high velocity. Such stars are observed in the Milky Way and may plausibly have been produced by a recent jet-outburst of SGR A*, which might also have produced the FERMI bubbles and the excess of positrons currently annihilating in the bulge of the Milky Way.