Stellar explosion’s afterglow burns brighter
The distant burst emitted 10 times more infrared energy than anticipated
1 3 Þ
gamma-ray burst, which released more energy in half a second than the Sun will in its 10-billion-year lifespan, could be brighter than first thought, as new measurements pinpoint its origin to a galaxy further away than anticipated.
The burst was first seen in May 2020.
As soon as word of the explosion spread, astronomers rushed to observe the area of sky it had occurred in and were able to get time on the Hubble Space Telescope just three days after the flash. These follow-up images revealed something very surprising – the infrared afterglow was 10 times brighter than anticipated.
“These observations do not fit traditional explanations for short gammaray bursts,” said Northwestern University’s Wen-fai Fong, who led the study. “Given what we know about the radio and X-rays from this blast, it just doesn’t match up.
A short
2 4
The near-infrared emission that we’re finding with Hubble is way too bright.”
The team needed to know how bright the blast was, so they measured how far away the explosion’s host galaxy is with Hawaii’s WM Keck Observatory.
“Distances are important in calculating the burst’s true brightness, as opposed to its apparent brightness seen from Earth,” says Fong. “Just as the brightness of a light bulb when it reaches your eye depends on both its luminosity and its distance from you, a burst could be really bright because either it is intrinsically luminous and distant, or not as luminous but much closer to us. We found it was more energetic than we first thought.”
The observations found the blast was further away, and so brighter, than expected, leading to questions over what had caused it. Most bursts like it are believed to originate from merging neutron stars, and a theory is that in this case the resulting object, a magnetar, had a strong magnetic field. This field could eject material out of the blast with enormous energies, causing it to glow brighter than normal. https://keckobservatory.org