Maunakea observatories investigate origins of castaway short gamma-ray bursts

Two Maunakea Observatories in Hawaiʻi – W. M. Keck Observatory and Gemini Observatory – took part in an international investigation into the mysterious origins of certain short gamma-ray bursts that seemed “homeless.”

It turns out these intensely bright flashes of light come from ultra-distant galaxies nearly 10 billion light-years away, which explains why they were so difficult to detect before.

An international team of astronomers has found that certain short gamma-ray bursts (GRBs) did not originate as castaways in the vastness of intergalactic space as they initially appeared.

A deeper multi-observatory study instead found that these seemingly isolated GRBs actually occurred in remarkably distant – and therefore faint – galaxies.

This discovery suggests that short GRBs, which form during the collisions of neutron stars, may have been more common in the past than expected. Since neutron-star mergers forge heavy elements, including gold and platinum, the universe may have been seeded with precious metals earlier than expected as well.

“Many short GRBs are found in bright galaxies relatively close to us, but some of them appear to have no corresponding galactic home,” said Brendan O’Connor, lead author of the study and an astronomer at both the University of Maryland and the George Washington University. “By pinpointing where the short GRBs originate, we were able to comb through troves of data from multiple observatories to find the faint glow of galaxies that were simply too distant to be recognized before.”

The study has been accepted for publication in the Monthly Notices of the Royal Astronomical Society and is available in preprint format on arXiv.org.

In addition to the two Maunakea Observatories in Hawaiʻi, astronomers also utilized data from the Gemini South telescope in Chile. Other observatories involved in this research include the NASA/ESA Hubble Space Telescope, Lowell Discovery Telescope in Arizona, Gran Telescopio Canarias in Spain, and the European Southern Observatory’s Very Large Telescope in Chile.

“This result could help astronomers better understand the chemical evolution of the universe,” according to a release issued by the W.M. Keck Observatory. “Merging neutron stars trigger a cascading series of nuclear reactions that are necessary to produce heavy metals, like gold, platinum, and thorium. Pushing back the cosmic timescale on neutron-star mergers means that the young universe was far richer in heavy elements than previously known.”

“This pushes the timescale back on when the universe received the ‘Midas touch’ and became seeded with the heaviest elements on the periodic table,” said O’Connor.