IceCube neutrino analysis identifies a possible galactic source of cosmic rays

Since the French physicist Pierre Auger has proposed in 1939 this is Cosmic rays They have to carry huge amounts of energy, and scientists have wondered what these powerful clusters of protons and neutrons that rain down on Earth’s atmosphere could produce. One possible way to identify such sources is to trace the paths that high-energy cosmic neutrinos take to Earth, where they are created by cosmic rays that collide with matter or radiation, resulting in particles that then decay into neutrinos and gamma rays.

Scientists with ice cube The Antarctic Neutrino Observatory has now analyzed a decade of these neutrino discoveries and has found evidence that an active galaxy called Messier 77 (also known as the Squid Galaxy) is a strong candidate for a high-energy neutrino emitter, according to new card Published in the journal Science. Brings astrophysicists one step closer to solving the mystery of the origin of high-energy cosmic rays.

“This observation represents the dawn of the ability to actually do neutrino astronomy,” said Janet Conrad, MIT Ice Cube Fellow. APS Physics says. “We have struggled for a long time to see the possible sources of cosmic neutrinos of the highest importance and now we have seen one. We have broken a barrier ”.

as such We have already informedAnd neutrinos Travel close to the speed of light. John Updike’s 1959 poem, “cosmic bitternessIt commemorates the two most distinctive features of neutrinos: they have no charge, and for decades physicists have thought they have no mass (in fact, they have very little mass). Neutrinos are the most abundant subatomic particles in the universe, but they very rarely interact with any type of matter. We are constantly bombarded every second with millions of these tiny particles, but they pass through them without even noticing them, which is why Isaac Asimov called them “ghost particles”.

This slow reaction rate produces neutrinos It is very difficult to detect, but because it is so light, it can escape unhindered (and therefore largely unaffected) from collisions with other particles of matter. This means they could provide astronomers with valuable clues to distant systems, reinforced by what can be learned with telescopes across the electromagnetic spectrum, as well as gravitational waves. Together, these various sources of information have been called “multi-messenger” astronomy.

Most neutrino hunters bury their experiments deep in the earth and it is best to cancel out strong interference from other sources. In the case of the IceCube, the collaboration includes optical sensor arrays the size of a basketball buried deep in the Antarctic ice. On the rare occasions when a transient neutrino interacts with the nucleus of an atom in ice, the collision produces charged particles that emit ultraviolet and blue photons. These are captured by the sensors.

So IceCube is well positioned to help scientists advance their knowledge of the origin of high-energy cosmic rays. Like Natalie Wolchofer with conviction Explained to Quanta In 2021:

A cosmic ray is just an atomic nucleus, a proton, or a group of protons and neutrons. However, the rare cosmic rays known as “extremely high energy” cosmic rays have the same amount of energy as tennis balls served by the pros. They are millions of times more powerful than the protons whizzing around the circular tunnel of the Large Hadron Collider in Europe at 99.999991% the speed of light. In fact, the most energetic cosmic ray ever discovered, dubbed an “oh my God” particle, hit the sky in 1991 at 99.9999999999999999999999999999951% of the speed of light, giving it roughly the energy of a bowling ball falling from it. shoulder height to a point.

But where do these powerful cosmic rays come from? There is a strong possibility Active Galactic Nuclei (AGNs), found in the middle of some galaxies. Its energy comes from supermassive black holes in the center of the galaxy and / or from the rotation of the black hole.