The nearby galaxy is a high-energy source of neutrinos, scientists say

eThe spiral galaxy Messier 77 has been identified as a source of high-energy neutrinos, a charge-free, almost massless and difficult to detect particle created by cosmic ray impacts (NASA / ESA / A. van der Hoeven)

Astronomers tracked high-energy neutrino particles in the active galaxy Messier 77, adding to the known point sources of these hard-to-detect particles.

The discovery opens the door to neutrino astronomy, using neutrinos to explore aspects of the universe that are otherwise difficult to observe, such as the dusty, occluded area around the supermassive black hole at the center of Messier 77. When supermassive black holes at the center del galaxies consume matter, emit enormous amounts of radiation, including gamma rays, and their galactic centers are considered “active”.

But where the gamma rays emitted by Messier 77 are blocked by the dense matter enveloping the galaxy’s core, the nearly massless, neutral-charged neutrino can slip through.

“Recent models of black hole environments in these objects suggest that gas, dust and radiation should block gamma rays that would otherwise accompany neutrinos,” said Hans Niederhausen, postdoctoral associate and analyst at Michigan State University for a new study. published Thursday in the magazine Science, reads a note. “This detection of neutrinos from the nucleus of [Messier 77] it will improve our understanding of the environments around supermassive black holes. “

Neutrinos are similar to electrons, but being neutrally charged and possessing almost no mass, they interact very weakly with other matter and energy. They come in two forms, low-energy and high-energy neutrinos.

Low-energy neutrinos are produced by thermonuclear processes such as those in the heart of the Sun. High-energy neutrinos, which means they have been accelerated to much higher speeds, are believed to be formed by high-energy cosmic-ray collisions in the sun. space.

“Revealing the origin of cosmic neutrinos and the relationship between neutrinos, gamma rays and cosmic rays is critical to deciphering the fundamental processes occurring throughout the Universe,” wrote Kohta Murase, a professor of physics at Pennsylvania State University in a perspective that appears in Science along with the new discoveries of Messier 77.

To detect high-energy neutrinos, the National Science Foundation IceCube Neutrino Observatory buried sensitive instruments in 1 billion tons of ice a mile and a half below Antarctica’s surface. The IceCube observatory detected the first known point source of high-energy neutrinos in 2018, TXS 0506 + 056, an active galaxy that emits jets of radiation directly to Earth, which is about 4 billion light years away.

Messier 77 is much closer to 47 million light-years from Earth, making it one of the closest identified sources of high-energy neutrinos.

The IceCube Observatory has detected 80 high-energy neutrinos from Messier 77, and with further research, the neutrino emissions from Messier 77 could become the standard against which future astronomical observations of neutrinos are compared.

“A neutrino can locate a source. But only an observation with more neutrinos will reveal the dark core of the most energetic cosmic objects, “said Francis Halzen, professor of physics at the University of Wisconsin-Madison, principal investigator of the new study. Although 80 neutrinos are still not enough to answer. to all the questions from his team, “they are definitely the next big step towards the realization of neutrino astronomy”.

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