Northwestern University astronomers have developed what is described as the most extensive inventory to date of the galaxies where short gamma-ray bursts (SGRBs) originate. NASA’s Neil Gehrels Swift Observatory first discovered an SGRB afterglow in 2005.
Gamma-ray bursts are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. When two neutron stars collide, they generate momentary flashes of intense gamma-ray light, known as SGRBs. While the gamma rays last mere seconds, the optical light can continue for hours before fading below detection levels (an event called an afterglow). Not only do the short bursts last less than about 2 seconds, the spectrum of light they emit is distinct.
Data was drawn from several highly sensitive instruments at W.M. Keck Observatory, the Gemini Observatories, the MMT Observatory, the Large Binocular Telescope Observatory and the Magellan Telescopes at Las Campanas Observatory.
The data was collected using several highly sensitive instruments together with sophisticated galaxy modelling. By deploying the observations and modelling, astronomers have succeeded in pinpointed the origins of 84 SGRBs. This succeeds in quadrupling the number of existing samples.
Of the 84 SGRBs, the scientists probed the characteristics of 69 of the identified host galaxies. This analysis of the data has revealed that 85 percent of SGRBs in the catalogue comes from young, actively star-forming galaxies and 20 to 40 percent of SGRBs occurred when the universe was much younger
The researchers also established that several SGRBs were spotted outside their host galaxies, as if they were ‘kicked out’. This is a finding that raises questions as to how they were able to travel so far away.
According to one of the lead researchers – Anya Nugent: “This is the largest catalog of SGRB host galaxies to ever exist, so we expect it to be the gold standard for many years to come.”
Since SGRBs are among the brightest explosions in the universe, the team have named the catalogue BRIGHT (for Broadband Repository for Investigating Gamma-ray burst Host Traits). All of BRIGHT’s data and modelling products are now publicly available online for community use.
It is hoped that the research will further astronomical understanding of these events and lead to a understanding what happens to stars after they die.
The research has been published in The Astrophysical Journal. The studies are titled “Short GRB host galaxies I” and “Short GRB host galaxies II”.
