In June 2015 the All-Sky Automated Survey for Supernovae snagged a huge fish: an extremely luminous object, dubbed ASASSN-15lh, whose spectrum appeared consistent with that of a supernova. The object’s luminosity peaked at about 2.2 x 1045 erg/s (2.2 x 1038 J/s), a factor of two higher than that of any other measured stellar explosion (see Physics Today, March 2016, page 14). Yet the ramifications of the supernova interpretation, including the sheer scale of nucleosynthesis necessary to generate so much energy, led scientists to consider alternative mechanisms.
Following a 10-month examination at multiple wavebands, one research team now argues that ASASSN-15lh is actually a star that got torn apart by the extreme tidal forces of its galaxy’s supermassive black hole (SMBH). The scientists, led by Giorgos Leloudas from the Weizmann Institute of Science in Israel and the University of Copenhagen in Denmark, found that ASASSN-15lh went...
