Possibly the first afterglow or newborn black hole of the kilonova?

The kilonova GW170817 has been studied for three and a half years, and scientists have come up with two scenarios that have never been seen before.

Possibly the first 'afterglow' or newborn black hole of the kilonova?

The kilonova GW170817 has been studied for three and a half years, and scientists have come up with two scenarios that have never been seen before.

A kilonova, an explosion caused by the collision of two neutron stars in a binary system, may have been observed for the first time ever in the history of astronomy by a team led by experts at Northwestern University and Illinois. merge.

Also known as r-type supernovae , kilonova are up to 1,000 times brighter than a classical nova, an explosive event in which a small, dense white dwarf absorbs material from a much larger companion star until it literally bursts, expelling with violence its outer layers and producing a strong flash, although of short duration. There's no limit on the number of novas that can be generated by a single 'vampirized' white dwarf unless one of them is strong enough to devastate the binary system all at once.

That wasn't the case, however, with GW170817, which was detected in 2017 and dubbed the "kilonova." A mystery new source of X-rays was discovered during the dramatic merger, which left behind a narrow jet of high-energy particles that didn't go away for more than three years.

There are two completely new avenues of exploration open to us.
For the first time, researchers have identified the source of X-ray radiation as expanding debris from an object merger, similar to an airplane's shock wave when it breaks through the sound barrier. This X-ray source was discovered in an article published in The Astrophysical Journal Letters, which can be found on the 'arXiv preprint server'. The shock wave generated the X-rays identified in the study, known as a kilonova 'afterglow', by heating the surrounding materials. The same material may have released X-rays after colliding with a newly formed black hole, though.

"Here, when researching the repercussions of the merging of two neutron stars, we have entered unexplored ground," says Aprajita Hajela, the first author of the article. We've never seen anything like this before, and it gives us a unique opportunity to study and comprehend novel physical processes that have never been observed."

After 3.5 years of careful observation.
The first neutron star merger observed by gravitational waves and electromagnetic radiation was GW170817 on August 17th, 2017. (or light). As a result of this, astronomers have been employing telescopes on Earth and in space to analyze the event in all wavelengths of the electromagnetic spectrum.

This discovery was made possible in part by the utilization of the Chandra X-ray Observatory and other telescopes, such as the Fermi Gamma-ray Space Telescope. However, as the narrow particle beam slowed down in early 2018, the X-ray emission decreased. The X-ray brightness, on the other hand, remained stable throughout the year 2020. To this I can only say, "Duh!"

In the study, main author Faffaella Margutti notes that "the X-rays ceased diminishing swiftly was our best proof that we were detecting something else in that source." To explain what we're seeing, a separate X-ray source appears to be required.

It's possible that the 'additional source' of X-rays is an unobserved kilonova glow or a newborn black hole.

One of the study's co-authors, Joe Bright, argues that this could be the first time we've observed a kilonova afterglow and the first time we've seen material falling into a black hole generated after merging kilonovae. Neutron stars are astronomical objects that have a mass of zero It would be intriguing to see what happens in either scenario."

However, how do you know which explanation is correct? It's only a matter of time before GW170817 is discovered, according to the researchers. The X-ray and radio emissions should get brighter in the next months or years if it is a kilonova afterglow. When matter is falling into a newly formed black hole, however, the X-ray emission should remain constant or rapidly diminish until no radio emission is detected.

In the words of co-author Kate Alexander, "additional study of GW170817 could have far-reaching repercussions. In the event of the merger producing a kilonova afterglow, this would indicate that the black hole did not form instantaneously. Astronomers may be able to investigate how stuff falls into a black hole just a few years after it is created if they use this object."

James Moody

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