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Scott Sutherland
Meteorologist / Scientific Editor
Thursday 12 July 2018, 11:50 – After a journey of 4 billion years, a tiny ghost particle may have provided astronomers with the solution to a persistent mystery of science – the source of high-energy cosmic rays.
For more than 100 years, astronomers have been trying to locate an elusive source of very high energy particles, known as cosmic rays, that they have detected from space.
According to two new articles published in the journal
Science the detection of a tiny "ghost particle", using a unique Antarctic Observatory called IceCube, as well as tracking observations of telescopes in the world and in space, eventually could identify this mysterious source. 19659006]
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In this artistic rendering, a blazar accelerates protons producing pions that produce neutrinos and gamma rays. Neutrinos are always the result of a hadronic reaction such as the one presented here. Gamma rays can be produced in hadronic and electromagnetic interactions. Credit: IceCube / NASA
On September 22, 2017, the Neutrino IceCube Ice Observatory, buried under more than one kilometer of Antarctic ice ice, recorded multiple flashes of light through its array of detectors. This detection, called IC170922, was identified as coming from a very high energy neutrino, a "ghost particle". Using the path taken by the particle as it pbaded through the observatory, astronomers retraced its trajectory in space and pointed terrestrial and space telescopes in this direction
on a particular celestial object at 4 billion light years. , just next to the Orion, which bears the rather heavy name of TXS 0506 + 056.
"Follow this high energy neutrino detected by IceCube up to TXS 0506 + 056 in fact the first time that we were able to identify a specific object as the likely source of such a high-energy neutrino, "said Gregory Sivakoff, of the University of Alberta, according to the University of Alberta. National Observatory of Radioastronomy
TXS 0506 + 056 is a & nbsp;
Blazar – An active and rotating supermbadive black hole, nestled in the heart of a distant galaxy, which emits intense magnetic fields as it turns in space , thereby producing twin streams of high energy particles.
This illustration depicts a blazar – an active black hole, with its accretion disk and twin streams of high-energy charged particles, flowing in space from its poles . Credit: Sophia Dagnello, NRAO / AUI / NSF
It was thought that even this extreme of the object could not explain the most energetic cosmic rays detected by astronomers, however.
"It is interesting that there was a general consensus in the astrophysical community that blazars were unlikely." Francis Halzen, Chief Scientist, Neutrino Glucon Observatory, University of Wisconsin -Madison, said Thursday in a statement
that the black hole is active because of its crushing gravity pulling into the surrounding matter, which then forms into a shiny disc of matter around it, called a As its powerful magnetic fields rotate through the accretion disk, the charged particles are picked up and transported to the magnetic poles, where they concentrate and are accelerated into intense particle beams that In essence, the black hole acts as a natural particle accelerator in the space, but at energies much higher than those that our accelerations Artificial tors here on Earth, can generate.
Now, the charged particles in these beams are of the same type here at Earth as cosmic rays – mostly positively charged protons and atomic nuclei – but it is highly unlikely that we can see the cosmic rays directly from TXS 0506 + 056 appear here on Earth, although one of the blazar particle clusters is This is because – as charged particles – these cosmic rays generate magnetic fields when they move in Space, and therefore their path can be changed by any other magnetic field that they encounter during their journey, such as those generated by stars and galaxies. Since even tiny trajectory changes can result in huge destination differences over billions of years, it is impossible to believe that a particular high energy cosmic ray detected here actually comes from this blazar.
Astronomers have made some progress As Halzen explains: "Now we have identified at least one source that produces high energy cosmic rays because it produces cosmic neutrinos. Neutrinos are the products of disintegration pawns. need a proton accelerator. "
Neutrinos are subatomic particles that are so small that they rarely interact with other materials as they travel through the universe. At this very moment, and during each every second of every day, about 10 trillion neutrinos pbad through our bodies and every piece of matter around us, we just do not feel them (and they have no idea we exist), because they pbad through or through all our atoms and molecules without encountering anything in their path.They can even pbad through the Earth without stopping.
On the occasion, however, by By chance, any of these neutrinos will have a frontal collision with an atom or a molecule.The more you put things in the trajectory of a neutrino and the denser this material is, the greater the risk of collision.
The trick, however, is to collide the neutrino with c something and having a detector available to see and record the collision.
The IceCube Neutrino Observatory of Antarctica is almost perfect for work.
The IceCube Neutral Ice Observatory encompbades one cubic kilometer of pristine ice deep below the surface of Antarctica and adjacent to the NSF Amundsen-Scott South Pole Station. In this illustration, based on an aerial view near the South Pole, an artistic rendering of the IceCube detector shows the interaction of a neutrino with an ice molecule. The display model is the way scientists represent data on the recorded light. Each colored circle represents the light collected by one of the IceCube sensors. The color gradient, from red to green / blue, indicates the time sequence. Credit: IceCube Collaboration / NSF
The observatory consists of a three-dimensional network of extremely sensitive light sensors evenly distributed in a giant cube of dense glacier ice, one kilometer away, located about 1.5 km below the surface of the Antarctic ice cap. [19659006LadensitédelaglaceetlatailledelamatricemaximisentnonseulementlepotentieldecollisionmaislaglaceclaireetimmaculéeàcetteprofondeurpermetauxcapteursduréseaudecapterlespetitséclairsdelumièrebleueconnussouslenomderayonnementCherenkovquisontproduitesparchaquecollisiondeneutrinosLetracédesdonnéesenregistréesparchaquedétecteurdanslamatricerévèlelatrajectoireduneutrinoentroisdimensionsetcecheminpeutêtreretracéjusqu'AlaSourCe[19659024] It s & # 39; is the IC170922 high energy neutrinos detected by IceCube 22 September 2017. L & # 39; display neutrinos shows a muon, created by the & # 39; interaction & # 39, a neutrino with ice very close to IceCube, which leaves a light track through the detector. In this display, the light collected by each sensor is represented with a colored sphere. The color gradient, from red to green / blue, indicates the time sequence. Credit: IceCube Collaboration
The return of the IC170922 neutrino on its trajectory was only the first sign of this mystery. Astronomers had to determine how a blazar, which was far enough in the list of potential sources of high-energy neutrinos and cosmic rays, could actually produce this neutrino.
For the next steps, they turned to other telescopes, both The Earth and Above, to study TXS 0506 + 056 – in as many light wavelengths as possible – for a possible "smoking gun".
Since this blazar has been observed for some time already, because it is a known source of high energy gamma rays, the researchers found in the recordings of a number of different telescopes, hoping to match the detection of this neutrino with other detections from this source.
On September 22, 2017, IceCube alerted the international astronomy community about the detection of a high-energy neutrino. About twenty observatories on Earth and in space made follow-up observations, which made it possible to identify what the scientists consider as a source of neutrinos with very high energy and thus of rays. cosmic. In addition to neutrinos, observations made across the electromagnetic spectrum included gamma rays, X-rays, and optical and radio radiation. These observatories are run by international teams with a total of over one thousand scientists supported by funding agencies in countries around the world. Credit: Nicolle R. Fuller / NSF / IceCube
What they found was an intense light of TXS 0506 + 056 – the strongest gamma ray eruption detected from this source in a decade of sightings from the Fermi telescope – which coincided with the arrival of the IC170922 neutrino.
Other telescopes also recorded observations of this event, in different wavelengths of light, with the radio observatory of the size of the Earth known as Very Long. Baseline Array actually detecting "nodes" of intense radio transmission inside the stream. According to the researchers, these bright nodes are probably regions of higher density material inside the particle beam, emitting strong energy discharges.
"The behavior we observed with the VLA is consistent with the emission of at least one of these nodes.This is an intriguing possibility that such nodes can be badociated with the generation of high energy cosmic rays and so to the type of high energy neutrino found by IceCube, "said Sivakoff, according to NRAO
. an event, at different wavelengths, while supporting a particular discovery, is an example of "multi-messenger astronomy". Another example of this "multi-messenger astronomy" was gravitational wave detection, which was accompanied by observations of different light emissions from the source.
WHY IS IT SO IMPORTANT?
Thus, astronomers and scientists understandably excited by this discovery, but what difference does it make? Why is it so important to know the source of high-energy neutrinos and cosmic rays?
This comes down to answering some of the weird questions that arose when we explored the universe up to now. In this case, specifically, the question is how can nature produce events of such intense energy that they are far beyond our comprehension.
More generally, however, where much of the energy from where the universe comes from, what does it mean about the structure of the universe? universe, and how does this affect our place in this universe?
Francis Halzen explains below:
With so many things at TXS 0506 + 056, the telescopes continue to observe it, and IceCube will no doubt be looking for more neutrinos from this source.
"There are a lot of exciting phenomena going on in this object," said Sivakoff.
Sources:
National Observatory of Radioastronomy |
University of Leicester |
University of Wisconsin
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