Kilonova afterglow potentially spotted for first time

An afterglow from a kilonova may have been detected for the first time.

A kilo nova is a blast 1000 times brighter than a classical nova. A jet of high-energy particles accompanied the merger event. Three-and-a-half years after the merger, the jet faded away, revealing a new source of X-rays.

The leading explanation for the new X-ray source is that expanding debris from the merger caused a shock similar to the sonic boom from a supersonic plane. The X-ray emissions from the shock were called kilonova afterglow. The X-rays were caused by materials falling toward a black hole.

It would be the first scenario for the field. The study was published today.

"We have entered uncharted territory here in studying the aftermath of a neutron star merger," said Aprajita Hajela, who led the new study. This gives us the chance to study and understand new physical processes that have not been observed before.

Hajela is a graduate student in the Department of Physics and Astronomy at the Weinberg College of Arts and Sciences.

The first neutron-star merger was detected by both light and light waves. Astronomers have been using telescopes around the world and in space to study the event.

Astronomers using NASA's Chandra X-ray Observatory observed X-ray emissions from a jet moving very close to the speed of light produced by the neutron star merger. The jet's X-ray emission faded as the jet continued to slow and expand. From March 2020 to the end of 2020, the X-ray emission was constant and the decline in brightness stopped.

This was a big clue.

The fact that the X-rays stopped fading quickly was our best evidence yet that something in addition to a jet is being detected in X-rays in this source.

The researchers think a black hole is behind the X-rays. Both scenarios have never been observed before.

This would be the first time we have seen a kilonova afterglow or the first time we have seen material falling onto a black hole after a neutron star merger, according to study co-author Joe Bright.

Astronomers will keep a close watch on the X-rays and radio waves. Over the next few months or years, the X-ray and radio emissions are expected to get brighter if it is a kilonova afterglow. If the explanation involves matter falling onto a black hole, the X-ray output should stay steady or decline rapidly, and no radio emission will be detected over time.

Kate Alexander said that the detection of a kilonova afterglow would imply that the merger did not produce a black hole. Astronomers may be able to study how matter falls onto a black hole a few years after its birth.

More information: The emergence of a new source of X-rays from the binary neutron star merger GW170817, arXiv:2104.02070 [astro-ph.HE] arxiv.org/abs/2104.02070 Journal information: Astrophysical Journal Letters , Astrophysical Journal Citation: Kilonova afterglow potentially spotted for first time (2022, February 28) retrieved 28 February 2022 from https://phys.org/news/2022-02-kilonova-afterglow-potentially.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.