original version of this story Appeared in Quanta Magazine.
100 trillion neutrinos pass by you every second, most of them coming from the Sun or Earth’s atmosphere. But some particles – those traveling much faster than the rest – flew here from distant and powerful sources. Astrophysicists have been searching for the origin of these “cosmic” neutrinos for decades. Now, the IceCube neutrino observatory has finally collected enough neutrinos to reveal a clear pattern of where they came from.
in Paper published in June science, the team revealed the first map of the Milky Way with neutrinos. (Normally, our galaxy is mapped with photons, or particles of light.) The new map shows a diffuse haze of cosmic neutrinos emanating from across the Milky Way, but mysteriously , no individual sources are noticeable. “It’s a mystery,” he said. Francis Halzenleads IceCube.
The results are as follows IceCube research from last fall,Also science, which was the first to connect cosmic neutrinos to individual sources. It showed that most of the cosmic neutrinos detected so far by the observatory came from the center of an “active” galaxy called NGC 1068. In the galaxy’s glowing core, matter spirals into the central supermassive black hole, somehow producing cosmic neutrinos.
“I’m really happy,” I said. Kate ScholbergHe is a neutrino physicist at Duke University, but was not involved in the research. “They actually identified a galaxy. This is the kind of thing the entire neutrino astronomy community has been trying to do forever.”
If we can identify the source of cosmic neutrinos, it opens the possibility of using these particles as new probes for fundamental physics. Researchers have shown that neutrinos can be used to crack the current standard model of particle physics and even test quantum descriptions of gravity.
But determining the origin of at least some cosmic neutrinos is only the first step. Little is known about how activity around some supermassive black holes produces these particles, and so far evidence points to multiple processes and circumstances.
Illustration: Meryl Sherman/Quanta Magazine; Image provided by IceCube Collaboration
The origin that has been sought for many years
Although neutrinos are abundant, they typically zip through the Earth without leaving a trace. To detect enough of them to recognize patterns in the direction in which they come, we had to build very large detectors. Built 12 years ago, IceCube consists of a series of detectors spanning several kilometers, drilled deep into the Antarctic ice. Each year, IceCube detects about a dozen cosmic neutrinos that are so energetic that they stand out even in the haze of atmospheric and solar neutrinos. More advanced analysis can find additional cosmic neutrino candidates from the remaining data.
Astrophysicists know that such high-energy neutrinos can only be produced when fast-moving atomic nuclei, known as cosmic rays, collide with matter elsewhere in the universe. And there are few places in the universe with magnetic fields strong enough to boost cosmic rays to sufficient energy. Gamma-ray bursts, the ultra-bright flashes that occur when several stars go supernova or when neutron stars spiral into each other, have long been thought to be one of the most plausible options . The only realistic alternative was an active galactic nucleus (AGN). An active galactic nucleus (AGN) is a galaxy with a supermassive black hole at its center spewing out particles and radiation as matter falls.
