Scientific breakthrough: Find the mysterious source of ghost particles after a century of detection

Scientists first discovered the source of a high-energy neutrino, revealing many things about the century-long mystery surrounding the particle.

Neutrinos are subatomic particles with almost no electrical charge, so it rarely interacts with the surrounding environment. In fact, these particles are also known as "" , constantly flowing through our bodies billions of particles per second that we don't know or feel.

Most of the neutrino particles on Earth originated from the Sun, but a small part of them originated from the most remote places in the universe . Their inherent elusiveness makes scientists unable to trace their origins, until today.

The IceCube Neutrino Observatory in Antarctica and a number of other observatories around the world have jointly observed a neutrino coming from a remote place, a giant elliptical galaxy with a supermassive black hole. spin very fast in the center.

Not stopping there, these cosmic neutrinos move with cosmic rays - rays made of high-energy particles that spill into the Earth continuously. Therefore, detectors not only capture a cosmic neutrino, but also receive super-fast cosmic rays.

Back in 1912, astronomers at the time always wondered about cosmic rays when they were first discovered at this time. At that time, the limitations of human knowledge about the nature of particles, making the cosmic rays become mysterious like many other celestial bodies in the universe.

'We have been searching for the source of these cosmic rays for a century and have finally found it,' said Francis Halzen, a scientist leading the study at the IceCube Neutrino Observatory and professor of physics. at the University of Wisconsin-Madison, said.

Simulation graphics about the source have just released neutrinos simultaneously with cosmic rays with tremendous speed.The supermassive black hole at the center of the galaxy accretion disk will emit a strong stream of matter into space and perpendicular to the galaxy disk.(Photo: DESY, Science Communication Lab).

The result comes from community efforts

It all started with IceCube, a highly sensitive detector buried deep about 1.5 km beneath dense ice in Antarctica. This system consists of 86 cables, each of which holds 60 modules with super sensitive optical functions, which detect a very sensitive light.

This detector is designed to capture characteristic blue light emitted by a neutrino when it interacts with an atomic nucleus. This light is due to another secondary particle created after interaction. The detector is buried deep so that the above ice layers prevent particles not neutrinos from contaminating the measurement results.

'To receive the signal from a very small force of neutrino interaction, physicists had to build an extremely large detector , ' said Dr. Susan Cartwright, a particle physicist at the University of Sheffield. For a year, the detector only received a few hundred neutrino particles, but they rarely interacted with the surrounding environment.

Measuring neutrinos as they interact with the surrounding is a step closer to determining their origin. Scientists like this find it hard to find a firefly in the middle of the bright fireworks night.

Before making this discovery, IceCube recorded neutrinos outside the Milky Way. The researchers did not accurately identify their origins at the time.

But on September 22, 2017, one of the distant neutrinos in the universe appeared at the detector. They carry extremely high energy, at about 300 teraelectron volts, 50 times the energy of protons passing through the world's largest particle accelerator.

Within a minute of being discovered, the detector sent a notice to astronomers around the world to find and direct the lens to observe the sky to search for evidence to identify the source. The origin of this neutrino particle.

Nearly 20 telescopes on the ground and in space scanned the sky with all electromagnetic spectra, from low energy radio waves to high-energy gamma rays. These observations, when combined together, captured the origin of the mysterious neutrino, its source known as TXS 0506 + 056 , located about 4 billion light-years from Earth.

Turning back the archives, the IceCube team found many other cosmic neutrinos that were observed at the end of 2014 and early 2015 also seem to come from there and have the same origin.

'By combining all the observations of observatories on the ground and in space, we have obtained compelling evidence of a source of neutrino that has a lot of energy, and comes with it. High-energy cosmic rays , 'said Albrecht Karle, scientist at IceCube and professor of physics at UW-Madison University.

Simulation graphics are redrawn based on the true image of IceCube, the neutrino observation deck located below 1.5 km of thick ice in Antarctica.(Photo: IceCube / NSF).

The universe is increasingly diverse with celestial objects

The source we have just discovered is a powerful, active super-bright galaxy that emits both light and particles simultaneously, one of which directly targets the Earth. (This explains why we get very strong signals from them.)

Astronomers have identified thousands of such sources in the universe but none of them emit neutrinos like TXS 0506 + 056."This is a special source and we have a responsibility to find out its secret ," Halzen added.

Not only can this source be identified that actually emits neutrinos, but scientists also want to know the mechanism that helps it accelerate. How does this source release both neutrinos simultaneously and into space with such tremendous speed?

Halzen expressed optimism that we will find answers to these questions in the near future. In the future, we will use two different types of signals to search the universe, as we did in this study.

Detecting neutrinos also helps reveal other mysteries that we are following. In October 2017, researchers announced that they had analyzed the collision between two super-heavy neutron stars by observing the electromagnetic radiation and gravitational waves emitted from them.

'The era of diverse cosmological physics is here. Each form, from electromagnetic radiation, gravitational waves now neutrinos, gives us a more complete understanding of the universe and important new insights about celestial bodies, the most powerful events on sky , 'said France Cordova, director of the National Science Foundation, IceCube management agency.