https://phys.org/news/2020-06-fast-radio.html Astronomers have peered into the home galaxies of fast radio bursts, ruling out supermassive black holes as a cause and bringing us a step closer to understanding the origins of these mysterious signals from outer space. Fast radio bursts—the hottest topic in astronomy right now—were first detected in 2007, but astronomers are still working out what could make such a brief signal appear so bright. In just a millisecond, a single burst releases more energy than our Sun emits in 80 years. An international team of astronomers led by Shivani Bhandari, an astronomer with CSIRO, Australia's national science agency, has made a key breakthrough by zooming in on the precise location of four fast radio bursts and having a look around their 'neighborhoods.' The research, which includes data from W. M. Keck Observatory on Maunakea in Hawaii, published today in The Astrophysical Journal Letters. "Just as video calls with colleagues show you their homes and give you a bit of an insight into their lives, looking into the host galaxies of fast radio bursts give us insights to their origins." Using a specially designed transient detector on CSIRO's ASKAP radio telescope in outback Western Australia, Bhandari and her team found the exact location of four fast radio bursts. "These precisely localized fast radio bursts came from the outskirts of their home galaxies, removing the possibility that they have anything to do with supermassive black holes," Bhandari said. This first detailed study of the galaxies that host fast radio bursts rules out several of the more extreme theories put forward to explain their origins, getting us closer to knowing their true nature. Co-author CSIRO's Professor Elaine Sadler said these fast radio bursts could not have come from a super luminous stellar explosion or from cosmic strings. "Models such as mergers of compact objects like white dwarfs or neutron stars, or flares from magnetars created by such mergers, are still looking good," said Sadler. more at link: the paper: https://iopscience.iop.org/article/10.3847/2041-8213/ab672e The Host Galaxies and Progenitors of Fast Radio Bursts Localized with the Australian Square Kilometre Array Pathfinder Abstract The Australian SKA Pathfinder (ASKAP) telescope has started to localize fast radio bursts (FRBs) to arcsecond accuracy from the detection of a single pulse, allowing their host galaxies to be reliably identified. We discuss the global properties of the host galaxies of the first four FRBs localized by ASKAP, which lie in the redshift range 0.11 < z < 0.48. All four are massive galaxies (log(M */M ⊙) ~ 9.4–10.4) with modest star formation rates of up to 2 M ⊙ yr−1—very different to the host galaxy of the first repeating FRB 121102, which is a dwarf galaxy with a high specific star formation rate. The FRBs localized by ASKAP typically lie in the outskirts of their host galaxies, which appears to rule out FRB progenitor models that invoke active galactic nuclei or free-floating cosmic strings. The stellar population seen in these host galaxies also disfavors models in which all FRBs arise from young magnetars produced by superluminous supernovae, as proposed for the progenitor of FRB 121102. A range of other progenitor models (including compact-object mergers and magnetars arising from normal core-collapse supernovae) remain plausible.
