Cosmic neutrinos traced at their source for the first time: A distant, violent black hole called a blazar – Science News

In a remote corner of the cosmos, 4 billion years ago, a tiny particle called a neutrino began its journey to Earth.

It was moving at the speed of light towards our neck of the universe, never deviating from its trajectory.

Being the smallest and lightest particle known to physics, the neutrino flew through matter as if nothing had happened. the electric charge, he remained immune to the influence of swaying magnetic fields.

Shortly after the neutrino unleashed, life emerged and flourished on Earth. Continents mixed in their tectonic dance. Plants, animals and fungi have spread to the four corners of the globe and mass extinctions have repeatedly destroyed them

and the neutrino continued its way until the evening of September 22, 2017 when it was dipped in the Antarctic ice and crashed.

More than one kilometer below the surface, this collision created another particle called muon

The muon continued to cross the ice in the same direction but unleashed a blue glow – the light that was detected. by balloon-like detectors suspended in nearby ice

In one minute, the trajectory of the neutrino was calculated from the light pattern captured by the detectors and sent to the telescopes from around the world

. eyes on this parcel of the sky, scouring for signs of the cosmic accelerator that spewed the neutrino all these eternities.

And for the first time, they found one.

Spot the first confirmed birthplace of a high-energy neutrino: a massive galaxy sheltering a supermassive black hole that spews streams of matter toward us.

The black hole is called a blazar. These objects were known to be a likely source of these disconcerting particles – but had never been caught in the act.

And this confirmation is a big problem, said Nicole Bell, astropartician physicist at the University of Melbourne who was not "

" This step of identifying a source is absolutely essential to truly astronomy with neutrinos, "she said.

Neutrinos, Dr. Bell explained, will now allow us to "see" otherwise invisible.

Underground Ghost Sensor

We are bathed in neutrinos, with trillions flying through our bodies every second, but they would never know

They sail for most of the Earth, earning their nickname "ghost particles".

There are many ways to make a neutrino. For example, they are a byproduct of nuclear fusion, created when hydrogen mixes to form helium in the sun.

And energetic particles – mainly protons – from space, called cosmic rays, bombard our atmosphere to produce showers

The neutrinos in the Sun and the atmosphere are mostly particles low energy

But these are the high-energy neutrinos created outside our galaxy, by the most cataclysmic events in the universe, which many astroparticle physicists are interested in.

The IceCube observatory near the South Pole recovers high-energy neutrinos since 2013. But to know precisely from where they came from, he needed to find out what he wanted. a little help from other telescopes.

If something is violent enough to spit out energy Neutrinos, according to reasoning, must also emit light, such as gamma rays, radio waves and X-rays.

Thus, When IceCube detected the tell-tale signs of a high-energy neutrino on September 22 last year, it sent the cosmic neutrino coordinate born from the astronomical community: a line of sight located just to the left of the constellation of Orion

In the first of two articles published today, the Fermi and MAGIC telescopes found a high energy gamma rays eruption that appeared to emanate from a known blazar called TXS 0506 + 056.

Other instruments, such as optical and radio telescopes, also measured the activity of TXS 0506 + 056 in the days and weeks that followed.

Have so many eyes on the sky According to James Miller-Jones, astrophysicist at the International Center for Astronomy Research at Curtin University, physicists use it to illuminate and understand the source.

"Some light frequencies are produced by different processes, so each region of the spectrum gives us a different window on what's going on," said Dr. Miller -Jones, member of the Very Large Array radio telescope team, who also observed the blazar about two weeks later. The IceCube Alert

All additional telescopes have garnered compelling evidence that TXS 0506 + 056 fired the neutrino on Earth, said Gary Hill, an astroparticle physicist at the University of Toronto. Adelaide and member of the IceCube collaboration

. To back up their findings, the team looked back into the IceCube archives and found a burst of about 15 other high-energy neutrinos, detected in 2014 and 2015, that also appear to come from the TXS 0506 + 056.

(19659058) To trigger a high energy neutrino, you need a powerful particle accelerator – as powerful as a supermassive black hole, for example. Astrophysicists believe that most massive galaxies have a supermassive black hole in their center. Our galaxy, the Milky Way, has one

It's powered at a very low rate, said Dr. Miller-Jones, so it's relatively low

But if they interact with matter or radiation "

" When pions disintegrate, they produce neutrinos and gamma rays, "said Dr. Hill.

Blazars are not the only source of neutrinos, says Dr. Hill. For example, another group of neutrino producers could be starburst galaxies, which are producing a lot of stars.

"There is evidence that they also make cosmic rays, if they do, it is a similar mechanism. [to a blazar] – Cosmic rays interact and make pions, which make neutrinos.

New Form of Astronomy

It is vital to know the origin of high energy neutrinos to develop a new way to observe the universe: neutrino astronomy .

Astronomy is traditionally based on light. But the problem with light is that it can be absorbed along the way, says Dr. Bell.