Final Report Summary - ULTRAS (Ultra-luminous supernovae : understanding their nature and cosmic evolution)
We have implemented a range of sky survey projects that link wide-field searching of the sky through to rapid computer processing and linking with large telescopes around to globe. These telescopes immediately follow-up these discoveries, looking for unusual and exotic explosions in the Universe.
We discovered some of the most luminous and energetic supernovae known. These are called super-luminous supernova, come from massive stars and are 100 times more luminous than normal core-collapse supernovae. Through detailed observational and theoretical analyses, we have shown they are most likely related to the formation of rapidly spinning magnetic neutron stars during the explosion. The extra energy comes from the energy stored in the rotating star that is extracted by the strong the magnetic field causing the object to spin down. We measured the physical properties of these, and discovered that many have an unusual eruption before the main supernova is visible.
The project developed physical models that were used to determine the mass and composition of the ejecta, showing that the exploding stars are carbon-oxygen cores of massive stars. We showed that their host galaxies all appear to be dwarf galaxies with a surprisingly low metallicity content.
While we searched for evidence of the theoretically predicted "pair-instability supernovae" , we could not unambiguously confirm their existence in the local Universe. Rather we found that the theoretical models of rotating, magnetic neutron stars fit the data better.
The spin-offs from this project included successful sky survey projects (Pan-STARRS and ATLAS and PESSTO), machine learning tools for fast identification of transients and using these sky survey projects to hunt for the electromagnetic counterparts to gravitational wave bursts. This field of multi-messenger astronomy opened up in 2017 with the discovery of a kilonova from a binary neutron star merger. The work we put in place enabled a major study combining PESSTO, Pan-STARRS and ATLAS data to analyse and physically model this kilonova.
We discovered some of the most luminous and energetic supernovae known. These are called super-luminous supernova, come from massive stars and are 100 times more luminous than normal core-collapse supernovae. Through detailed observational and theoretical analyses, we have shown they are most likely related to the formation of rapidly spinning magnetic neutron stars during the explosion. The extra energy comes from the energy stored in the rotating star that is extracted by the strong the magnetic field causing the object to spin down. We measured the physical properties of these, and discovered that many have an unusual eruption before the main supernova is visible.
The project developed physical models that were used to determine the mass and composition of the ejecta, showing that the exploding stars are carbon-oxygen cores of massive stars. We showed that their host galaxies all appear to be dwarf galaxies with a surprisingly low metallicity content.
While we searched for evidence of the theoretically predicted "pair-instability supernovae" , we could not unambiguously confirm their existence in the local Universe. Rather we found that the theoretical models of rotating, magnetic neutron stars fit the data better.
The spin-offs from this project included successful sky survey projects (Pan-STARRS and ATLAS and PESSTO), machine learning tools for fast identification of transients and using these sky survey projects to hunt for the electromagnetic counterparts to gravitational wave bursts. This field of multi-messenger astronomy opened up in 2017 with the discovery of a kilonova from a binary neutron star merger. The work we put in place enabled a major study combining PESSTO, Pan-STARRS and ATLAS data to analyse and physically model this kilonova.