Gonna need a bigger bomb: the diversity and power sources of hydrogen-rich superluminous supernovae

by Dr Tuomas Kangas (UTU, Finland)

Wednesday 14 Jan 2026, 13:30 → 14:30 Europe/Stockholm

FC61 (AlbaNova Main Building)

The most powerful explosions of massive stars are known as superluminous supernovae (SLSNe). These explosions are too luminous (and stay luminous too long) to be powered by the same mechanisms as normal supernovae are, and additional power sources are needed. One possible SLSN engine is a newborn magnetar, i.e. a highly magnetic neutron star, which deposits its rotational energy to the supernova ejecta -- these have been established as the likely mechanism behind H-poor SLSNe. On the other hand, practically all H-rich SLSNe show signs of interaction with the circumstellar medium (CSM), produced through pre-explosion mass loss in the progenitor star. Such interaction can efficiently convert the kinetic energy of the ejecta into luminosity, but whether this is always enough, or whether these H-rich stars also form magnetars when they die, is a different question -- especially for some SLSNe that do not show the usual CSM signatures in their spectra. Answering this question can elucidate how very massive stars evolve in their final stages. In this seminar I will summarize our current knowledge of these rare events and their subtypes, including recent and preliminary results highlighting the need for both strong, asymmetric late-time mass loss and occasionally magnetars -- or even something else.