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The "ghost" particles known as neutrinos have baffled scientists for decades
They are part of the family of fundamental particles that make up all known matter.
But neutrinos circulate
Most cross the Earth as if it were not there, which makes them exceptionally difficult to detect and study this, the researchers found that the Sun creates many or even our own atmosphere.
Only the source of a group of high-energy neutrinos, known as cosmic neutrinos, remained particularly elusive.
a group of scientists discovered that a distant galaxy driven by a supermbadive black hole can fire a jet of these cosmic neutrinos directly to Earth.
Their discoveries were published in the journal Science Thursday
First step: trapping a neutrino
It all starts with IceCube, a very sensitive detector, buried around two kilometers under the Antarctic ice, near the American Amundsen-Scott station at the South Pole.
"To obtain a measurable signal from the small fraction of neutrinos that interact with matter, physicists need to build extremely large detectors," says Dr. Susan Cartwright, particle physicist at the University of Sheffield , United Kingdom.
BBC News, tells the measurement of cosmic neutrinos among those who were created closer to home, how to try counting fireflies in a fireworks " .
But on September 22, 2017, one of these neutrinos appeared near IceCube and decided to interact with the surrounding mate, creating another particle called muon.
Missing the stealth of the neutrino, this muon squeezed into the ice in the same direction as its ancestor, triggering other atoms along the way. leaving a visible trace that IceCube could capture.
"[IceCube] measures this trace of light," says Professor Albrecht Karle of the University of Wisconsin-Madison, USA, who participated in the discovery.
"We can do this with quite accurate so that we can measure the direction of the trace (neutrino)," he adds
Thus, IceCube was able to calculate the region Approximate Space
Step Two: Track It Home
In 43 seconds, an alert was sent for other telescopes to join the hunt.
Two years earlier, the IceCube team had decided that in place to accumulate their possible find In order to publish them, they would send "telegrams of astronomy" to invite Other researchers participate in the search as soon as a signal is detected.
"Traditionally in astronomy we have looked at images of the sky, as if they were static, but in reality they are a movie, and there are flashes and moving things all the time. publish an article for other astronomers to read three years later, we went into mode in real time ", explains Professor Karle
.the point of origin of the neutrino
The complicated part, explains Karle, is that IceCube can cover up to half a degree of sky, that is, a region that looks like the size of the moon, but that can cover many galaxies and other objects
However, this time there was good news
A galaxy with a black hole "monster" About 100 million times greater than our Sun, I was at the right place.
Third Step: Blazares by the shoulder of Orion
Few 4 billion light years from Earth just beside the left shoulder of the Orion constellation This galaxy has a nucleus It is brilliant because of the energy of its central black hole.
When matter falls into the black hole, large jets of charged particles emerge at right angles, converting them into mbadive particle accelerators. "Only the jet can extend up to nearly a million light-years away, which, of course, is larger than the large CERN hadron collider (accelerator). of particles in Switzerland), "laughs professor Karle
It is perhaps not surprising that the neutrino detected by IceCube arrives with ] 40 times more energy than the accelerated particles at CERN, despite its long journey
This particular type of galaxy is known as blazar, because one of the jets is directed directly to the Earth.
"So we are really in the line of fire. We look at the monster in the eyes, so to speak, "adds Professor Karle
What's new?
Although they were not originally listed as possible sources of cosmic neutrinos, this is tangible proof that blazares generate elusive particles.
"This is an extremely exciting news ," says Dr. Cartwright, who was not involved in the study.
"We can expect that after this observation" After its initial detection, the IceCube team examined previous recordings of neutrino interactions and discovered that several others were arrived under the direction of the same galaxy
"The probability that this excess of neutrinos arises by chance is less than 0.03%", adds Cartwright.
Confirm the discovery by others or the European Southern Observatory in Chile (ESO) made the last success for astronomy of several messages : detections that combine electromagnetic information, such as data visual and radio, with signals such as gravitational waves and neutrinos.
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