Scientists have, for the first time, recorded a luminous burst of millimeter wavelength caused by the merger of a neutron star with another star.
Not only is this the first time scientists have successfully recorded a neutron star merger, but the team has also confirmed that the resulting flash of light is one of the most energetic short-lived gamma-ray bursts. ever observed, leaving behind one of the brightest. recorded afterglows.
The team, led by Northwestern University and Radboud University in the Netherlands, used the Atacama Large Millimeter/Submillimeter Array (ALMA) to perform the observation. Located in the Atacama Desert in Chile, the ALMA array is made up of 66 radio telescopes, making it the largest such telescope in the world.
“This short gamma-ray burst was the first time we’ve attempted to observe such an event with ALMA,” said ALMA program principal investigator Wen-fai Fong of Northwestern.
“Afterglows for short bursts are very hard to find, so it was spectacular to see this event shine so brightly. After many years of observing these bursts, this surprising discovery opens up a new area of study, as it motivates us to observe many more with ALMA and other telescope arrays in the future.
As the National Radio Astronomy Observatory (NRAO) explains, gamma-ray bursts (GRBs) are the brightest and most energetic explosions in the universe and are capable of expelling more energy in seconds than the Sun. will not emit any throughout its life.
Short-term GRBs tend to last for fractions of a second and although they expel a ton of energy and leave an afterglow – an emission of light caused by the jets’ interaction with the surrounding gas – they are still difficult to detect and less than half a dozen have already been detected at radio wavelengths. Until now, none had been detected in millimeter wavelengths.
“Millimeter wavelengths can tell us about the density of the environment around the GRB,” says Genevieve Schroeder, study co-author and graduate student in Fong’s research group.
“And, when combined with X-rays, they can tell us about the true energy of the explosion. Because the emission at millimeter wavelengths can be detected longer than in X-rays, the Millimeter emission can also be used to determine the width of the GRB jet.
“What makes GRB 211106A so special is that it is not only the first short-lived GRB we have detected in this wavelength, but also, through millimeter and radio detection, we have been able to measure the opening angle of the jet”, Rouco Escorial, study co-author and postdoctoral fellow at CIERA, adds.
“The millimeter and radio bands gave us the information we needed to measure the opening angle of the jet. This is essential to infer the actual rates of short GRBs in our universe and to compare them with the rates of binary neutron star or neutron star and black hole mergers.
The explosion, called GR 211106A, which scientists witnessed occurred when the Universe was still quite young: barely 40% of its current age. As a result, the light from the explosion is incredibly dim.
“The light from this short-lived gamma-ray burst was so faint that, while early X-ray observations with NASA’s Neil Gehrels Swift Observatory saw the explosion, the host galaxy was undetectable at that wavelength. , and scientists have been unable to determine exactly where the explosion came from,” writes the NRAO.
“The afterglow is essential for determining which galaxy a burst originated from and for learning more about the burst itself. Initially, when only the X-ray counterpart had been discovered, astronomers thought this burst might have come from ‘a nearby galaxy,’ said Tanmoy Laskar, who will soon begin work as an assistant professor of physics and astronomy at the University of Utah. . and adds that a significant amount of dust in the area has also obscured the object of detection in optical observations with the Hubble Space Telescope.
“Hubble observations have revealed an unchanging field of galaxies,” Laskar explains. “ALMA’s unparalleled sensitivity allowed us to more accurately pinpoint the location of the GRB in this field, and it turned out to be in another faint galaxy, which is further away. That, at in turn, means this short-lived gamma-ray burst is even more powerful than we first thought, making it one of the brightest and most energetic on record.
The full sighting research report will be published in an upcoming issue of Letters from the Astrophysical Journal.
Picture credits: ALMA (ESO/NAOJ/NRAO), M. Weiss (NRAO/AUI/NSF)