Research on stellar explosions at the University of Turku

The main research interests of the group focus on observational work on extragalactic astrophysical transients, including supernovae, tidal disruption events, and kilonovae.

Supernovae are among the most energetic phenomena in the Universe marking the end-point in the evolution of certain stars, producing neutron stars and in more exceptional cases stellar mass black holes. These explosions play a vital role in our understanding of stellar evolution, the synthesis of heavy elements, and through feedback processes also in galaxy evolution. Furthermore, they can also be used as probes of the cosmic star formation history which is one of the most fundamental observables in astrophysical cosmology.

While thousands of supernovae are discovered each year, luminous transients occurring within the nuclei of galaxies have been largely missed or overlooked by the surveys. Such events may arise when a star passing close to a supermassive black hole at the center of a galaxy is disrupted by tidal forces caused by the gravity of the black hole. Tidal disruption events provide a means of probing central black holes in galaxies and testing scenarios of accretion onto supermassive black holes important for our understanding of galaxy evolution.

The discovery and follow-up of the first electromagnetic counterpart of a gravitational wave source marked the beginning of a new era in multi-messenger astronomy. GW170817 was a landmark event, consistent with the merger of two neutron stars (a “kilonova”) that radiated across the electromagnetic spectrum. It provided unambiguous proof that neutron star mergers are a source of rapid neutron capture elements in the Universe.