An international research group led by Erkki Kankare at Queen’s University Belfast, UK, and with Professor Peter Lundqvist from the Oscar Klein Centre as co-investigator, has discovered a new population of extremely bright explosions in distant galaxies. A new paper focuses on the brightest of these events : PS1-10adi, which was discovered with a telescope on Hawaii as part of an all-sky survey that aims to discover variable (i.e., transient) objects. The host galaxy of the PS1-10adi explosion is located more than 3 billion light years from the Earth. This event was extremely interesting because of its brightness and location in the central region of its host galaxy. The team has monitored the event for several years.
“The total energy radiated by PS1-10adi is 1,000 times that of normal supernova explosions. The host galaxy of the event is also an active, so-called Seyfert galaxy, with a roughly 10-million- solar-mass supermassive black hole in its nucleus. The spectroscopic properties of PS1-10adi, and the slow and smooth evolution of the event, showed that it wasn’t a normal outburst of a supermassive black hole in an active galaxy,” Lundqvist explains.
Based on the data analysis, the research group converged on two possible paths of origin for PS1-10adi. Either it is one of the brightest supernova explosions ever, originating from extremely massive stars of several tens to up to a few hundreds of solar masses, or it is a disruption of a star by the gravitational tidal forces of the supermassive black hole in the galaxy nucleus. In both cases, the observations suggest that, during the event, explosively expanding material collided with dense ambient gas.
“Future observations with a larger sample of new events will enable a better understanding of the true nature of these extremely energetic events. Because of their significant brightness, these events can also be used in future as tools to probe the properties of distant galaxies,” Lundqvist says.
Observations of the PS1-10adi event were carried out mainly with the 2.56-metre NOT on La Palma, Canary Islands, which is one of the best observatory sites in the world. The NOT has an important role both for research in astronomy in Sweden and in the training of a new generation of researchers. Its flexibility makes the NOT a very competitive telescope internationally and extremely well suited for observing supernovae and other transients, and is heavily used by researchers at Stockholm University.
