Three years ago, history was made as astronomers detected for the first time a collision of neutron stars thanks to the LIGO-Virgo gravitational wave detectors, as two dead celestial bodies came together in a bright flash of gamma-radiation, preceded by rippling gravitational waves.
Astronomers believe they have captured the instant when two dense neutron stars collided in an astronomical event called a kilonova to form a strange magnetic star.
A broad range of telescopes caught a tell-tale blinding flash of a short gamma-ray burst 5.5 billion light-years away, reminiscent of the kilonova explosion linked with the 2017 neutron star collision detected in a historic astronomical breakthrough.
However, according to research that has been accepted into The Astrophysical Journal and is available on arXiv, there was something about the current kilonova accompanying the gamma-ray burst, dubbed GRB 200522A, that was very unusual.
Observations showed the flash included around ten-times more infrared light than predicted, with the research suggesting the collision produced something quite unexpected.
The flash had been captured in near-infrared wavelengths by the Hubble Space Telescope.
Strange New Phenomenon
The astronomers were alerted to the possibility of the vent by NASA’s Neil Gehrels Swift Observatory, a space telescope designed to be able to detect gamma-ray bursts early, with its Burst Alert Telescope.
After that initial warning, other space and terrestrial telescopes, such as The Very Large Array, the W.M. Keck Observatory, and the Las Cumbres Observatory Global Telescope network zoomed in on the location.
They obtained an electromagnetic profile of the event from radio wavelengths to X-rays, to show it was a short gamma-ray burst associated with merging neutron stars.It was the Hubble Space Telescope, observing the event in near-infrared, that made astronomers realize a new phenomenon was occurring.
He added that the scientists then had to step away from “conventional thinking” to figure out “what that meant for the physics behind these extremely energetic explosions.”
While astronomers believe that the two neutron stars in the 2017 event, dubbed GW 170817, merged to form a black hole, on this occasion the near-infrared brightness of the GRB 200522A kilonova might indicate the two neutron stars merged to form a rare magnetar.
Magnetars are a type of neutron star that possess extremely powerful magnetic fields, around 1,000 times that of an average neutron star.
Only 24 have been confirmed, to date, in our own galaxy, the Milky Way.
Only one kilonova to date has been confirmed – the one associated with GW 170817 of 2017.
If the bright burst witnessed by Hubble came from a magnetar that ejected energy into the kilonova material, in a few years, the ejected material will produce light observable on radio wavelengths. Accordingly, follow-up radio observations may prove that this was a magnetar.
The Breakthrough Event
Back in 2017 the historic first detection of a collision between two neutron stars, 130 million light-years away, in an event dubbed GW 170817, was hailed as a breakthrough only possible due to gravitational wave astronomy.
The latter had identified the event and alerted observatories, pinpointing the area to watch. This was only the fifth gravitational wave detection, with the previous four detections from mergers between binary black holes, uniting to form a big black hole.
visual of gravitational waves from two converging black holes is depicted on a monitor behind Laser Interferometer Gravitational-Wave Observatory (LIGO) Co-Founder Kip Thorne as he speaks to members of the media following a news conference at the National Press Club in Washington, Thursday, Feb. 11, 2016
While previously there were only two detectors of gravitational waves, the LIGO interferometers in Livingston, Louisiana and Hanford, Washington, the addition of a third – Virgo’s interferometer in Italy, boosted location accuracy.
Now, a magnitude of data across diverse signals is conducive in helping astronomers better understand these events.
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