Science

Drexel Astrophysicist Proves the Origin of Neutrinos - DrexelNow

Drexel Astrophysicist Proves the Origin of Neutrinos - DrexelNow

On September 22, 2017, a shock wave of blue light flashed through the crystal-clear glacial ice a mile beneath the South Pole, heralding an entirely new way of looking at the universe.

They travel at speeds just shy of the speed of light and rarely interact with other matter, allowing them to travel unimpeded across distances of billions of light-years.

The majority shoot right through the Earth as though it isn't even there, making them exceptionally hard to detect and study.

"The evidence for the observation of the first known source of high-energy neutrinos and cosmic rays is compelling", said Francis Halzen, a University of Wisconsin-Madison professor of physics and the lead scientist for the IceCube Neutrino Observatory.

"In our case, we saw an active galaxy, which is a large galaxy containing a huge black hole at its centre", explains Kowalski. TXS 0506+056, as it is known, is a blazar, a giant elliptical galaxy with a supermassive black hole spinning at its core. Scientists find them when one of the jets they emit travels in the direction of Earth. "For years, we've had a long list of potential sources for high-energy neutrinos".

Darren Grant, spokesman for the IceCube scientific collaboration said, 'Neutrinos provide us with a new window with which to view the universe.

"They can extend to nearly a million light years, just the jet". This is still a strictly theoretical kind of neutrino that would come from dark matter.

Before now, tracing the origins of this type of cosmic ray has been impossible, Dolinski said, because most are charged particles. In fact, it is said that trillions of these particles are flowing through our bodies undetected every second.

Blazars have several million to several billion times the mass of our Sun. In particular, measurements of neutrinos can reveal the mechanisms for particle acceleration of the proton beam in the densest environments that even high-energy gamma rays may not escape.




"We had to run detailed reconstructions of the neutrino event direction as fast as possible before sending the alert from IceCube to all of its partners", said Kopper, adding the team was only able to react as quickly as they did because of access to a highly specialized computer cluster funded by the Canada Foundation for Innovation and made at the U of A.

At the end of September past year, Halzen and his team found the first hints of the source of these mysterious rays, studying data collected by the IceCube neutrino Observatory, built deep in the ice of the South pole of the Earth. To detect a neutrino would require a lot of nuclei in a small area.

When that happened, observatories around the world, from an optical telescope in the Canary Islands to a gamma-ray observatory orbiting hundreds of miles above the Earth, leapt to action. In the first of the papers, they describe the detection and team up with numerous groups of astronomers to perform so-called multi-messenger astronomy - observing the same object in light and neutrinos.

"The popular image of the lone astronomers is, I'm afraid, out of date", says Dawn Williams, a particle astrophysicist at the University of Alabama and a member of the IceCube team.

Recent years have seen astronomy begin to broaden beyond the photon. The astronomers found stronger emissions of light and gamma rays than usual from the center of the galaxy beyond, showing that the neutrinos came from that black hole.

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Acting as "messengers", neutrinos directly carry astronomical information from the far reaches of the Universe.

Did INTEGRAL record the high-energy neutrino source?

The tricky part, explains Prof Karle, is that even though IceCube can work this out to within half a degree of sky, that is still about the size of the Moon as we see it from the Earth's surface.