Did the black hole that engulfed the star generate neutrinos? | urania

New accounts show it Black hole Perhaps the absorbing star didn’t generate enough energy to send it neutrino.

In October 2019, a high-energy neutrino hit Antarctica. A neutrino that was extremely difficult to detect sparked the interest of astronomers: what could generate such a powerful molecule?

Scientists have traced the neutrino’s path back and estimated that the tracking led to it giant black holeHe had just shredded and swallowed a star. known to have happened tidal disturbance (TDE)AT2019dsg occurred just a few months ago – in April 2019 – in the same region of the sky where the neutrino originated. Astronomers said this brutal, violent event must have been the source of a powerful molecule.

However, new research challenges this claim.

W work Published in October 2021 in The Astrophysical Journal, a team of scientists provided new and comprehensive radio observations and data on the AT2019dsg, allowing the team to calculate the energy emitted by the event. The results show that the AT2019dsg did not generate the energy needed to make the neutrino; The team concluded that what he threw was “normal”.

Black holes are messy eaters
While it may seem counter-intuitive, black holes don’t always devour everything within their reach.

When a star travels too close to a black hole, gravitational forces begin to pull on it. Eventually, the elongated matter orbits around the black hole and heats up, creating a flash in the sky that astronomers can see from millions of light years away.

But when there is a lot of matter, black holes can’t devour it all at once Kate Alexander, co-author of the study, which describes black holes as “messy eating.” Some gas is spit out again during this process.

This debris is dumped back into space in the form of liquid waste or jets — which, if powerful enough, could theoretically generate a subatomic particle known as a neutrino.

Incredible source of neutrinos
Use very large array (VLA) in New Mexico and Atacama Large Millimeter/Meter Matrix (ALMA) In Chile, the team was able to monitor the AT2019dsg, 750 million away from us. light years, for 500 days after the black hole began to swallow the star. Intense radio observations made the AT2019dsg the best studied TDE to date, revealing that radio brightness peaked about 200 days after the event began.

According to the data, the total amount of energy in the flow was equivalent to the energy that the Sun would produce in 30 million years. While that might sound impressive, the strong neutrino that was observed on October 1, 2019 would require a source 1,000 times more energetic.

Yvette Cendes, a PhD student at the Center for Astrophysics who led the research says: If this neutrino is somehow derived from AT2019dsg, then the question arises: why haven’t we observed supernova-associated neutrinos at this distance or closer? They are more common and have the same velocity energy.

The team concluded that it was unlikely that the neutrino was derived from the specific TDE. However, if they do, astronomers are far from understanding TDE and how neutrinos are sent.

TDE AT2019dsg was first observed on April 9, 2019 by the Zwicky Transient Facility in Southern California. A neutrino known as IceCube-191001A has been discovered Ice Cube Neutrino Observatory Falls in Antarctica after six months.

Detail:
Agnieszka Nowak

more information:

Source: CfA

In the illustration: An artistic view of the AT2019dsg tidal disturbance event, as a supermassive black hole extends and engulfs the star. Source: DESY, Science Communication Lab