The discovery of a source of cosmic rays is a triumph of "Multimesssenger astronomy"

Cosmic rays travel to Earth at relativistic deep space velocities, but their origins have intrigued astronomers for more than a century. Yesterday (12 July), an international team of scientists announced tracing an badociated particle to its origin, revealing for the first time a source of cosmic rays.

Discovery is a triumph of multimessenger astronomy, in which scientists use several types of signals – in this case, electromagnetic waves and ghost-like particles called neutrinos – to probe cosmological questions that are impossible to respond to Old (a message) way.

The multimessenger-astronomy era began in October 2017, when researchers announced that they had observed gravitational and light waves emitted by a pair of fused neutron stars. And the trend continues with the new discovery. [Tracing a Neutrino to Its Source: The Discovery in Pictures]

"Today, we are very happy to report [that] now that we know something about cosmic accelerators in the joint detection of neutrinos and gamma rays," Regina Caputo, who is working on the Fermi Gamma-Ray space telescope. , said at a press conference yesterday.

Astronomers have long sought the ability to synthesize several types of signals. At the press conference, astrophysicist Razmik Mirzoyan, of the Max Planck Institute of Physics in Munich, Germany, recalled the discussions with his colleagues decades ago.

"They said:" In the future, perhaps it will be possible to measure sources not only across the electromagnetic spectrum, but also … with ground instruments [detecting] neutrinos ", said Mirzoyan. "And I am very happy, because today it becomes reality."

A cosmic mystery

As early as the 1780s, French physicist Charles-Augustin de Coulomb noticed that charged particles neutralized the electrical charge of some of his experiments.In 1912, the Austrian scientist Victor Hess first demonstrated that these particles were coming from the space.He used a hot air balloon to take a detector in the sky, where he quickly observed nearly three times as much ionizing radiation as at ground level.This indicated that mysterious particles came from above.

We now know that cosmic rays consist of different subatomic particles: negatively charged electrons and positively charged protons and atomic nuclei. Some cosmic rays have energies that far exceed what we can achieve even in our larger particle accelerators. Very few phenomena in the universe can accelerate particles at these speeds, which simply adds to the mystery of the phenomenon.

Quintillions of cosmic rays bombard the Earth from space every second. But it is almost impossible to trace the paths of these atomic fragments to their sources. Most of them break down into atoms in the upper atmosphere, creating a cascade of secondary particles that rain down to the surface of different directions. In addition, most cosmic rays carry an electric charge, which means that their path changes each time they encounter a magnetic field. And the space is filled with magnetic fields, from the relatively weak magnetosphere of our own planet to the powerful magnetic vortices generated by the magnetars.

The challenge of cosmic ray tracing is precisely the type of problem that multimessenger astronomy can tackle most effectively. By recognizing the limits of cosmic ray detection, astronomers could shift their energy to another source of information.

Neutrinos: Silent Messengers

Neutrinos also rain on Earth numbers every second. However, these odd particles, which have no electrical charge and are almost mbadless, can cross entire galaxies without any interaction. When scientists detect a neutrino, its path goes back to its origin.

Astronomers have come to realize this because processes that accelerate protons to the energy levels observed in cosmic rays generate high energy neutrinos. It is precisely the type of neutrino that the IceCube Neutrino Observatory, located at Amundsen-Scott South Pole Station, was detected on September 22, 2017.

Within minutes of detection of the particle, IceCube automatically alerted the other observatories. According to a report by the Deutsches Elektronen-Synchrotron, a research center on particle accelerators in Hamburg, Germany, the cascade of activity reflects efforts made following the detection of waves gravitational. last year. A rapid alert sent by a type of observatory – in this case, a gravitational wave detector – allowed others to follow the observation on a wide range of different signals. The events led to the first multimessenger observation of the fusion of neutron stars, which provided a wealth of information about these superdense celestial objects. [Did a Neutron-Star Collision Make a Black Hole?]

In the recent discovery, electromagnetic signals from gamma rays to radio waves revealed that the neutrino originated from a supermbadive black hole rotating at the center of a galaxy at some 4 billion dollars. ; light years. It turns out that one of the jets of high energy particles that go away from the black hole points directly to the Earth. Astronomers call these blazar objects, and although they are not the most powerful phenomena in the universe, they certainly have the energy to accelerate a proton up to speeds observed in cosmic rays.

"It is interesting that there was a general consensus in the astrophysical community that blazars were unlikely to be sources of cosmic rays, and here we are," said Francis Halzen, chief scientist of IceCube, professor of physics at the University of Wisconsin-Madison, in a statement. "Now we have identified at least one source that produces high-energy cosmic rays because it produces cosmic neutrinos."

The combination of information from different messengers promises to provide scientists with even more prospects in the future.

"We have not yet identified neutrinos in relation to gravitational events," said Olga Botner, astrophysicist and former spokeswoman for the IceCube experiment, at the press conference of 39, yesterday. "But we believe it's a discovery just waiting around the corner."

Follow Harrison Tasoff @harrisontasoff . Follow us on @Spacedotcom Facebook and Google+ . Original article on Space.com .