Multimessenger Astronomy is the reason behind the Discovery of a Cosmic-Ray Source

Multimessenger Astronomy is the reason behind the Discovery of a Cosmic-Ray Source

Neutrinos helped the scientists to figure out a source of the cosmic rays.

Cosmic rays have been entering the atmosphere of our planet ever since. The source of these rays have always been a mystery for astronomers as they couldn’t figure out a scientific explanation for their opinions. Having said that, the announcement of an international team of researchers might change their fortunes as they claim to have tracked an associated particle back to its origin. All of this was possible due to the ‘Multimessenger Astronomy’ where multiple types of signals are used by the scientists. A combination of Neutrinos and Electromagnetic waves was used to answer this long-lasting query. Regina Caputo, a Representative of the Fermi Gamma-ray Space Telescope of NASA, was very delighted as she said,

Today, we’re really excited to report [that] now we know something about cosmic accelerators in the joint detection of neutrinos and gamma rays.”

Victor Hess, an Austrian scientist, was the first man to indicate that these charged particles were coming from space. In 1912, he sent a detector high in the sky by making use of a hot-air balloon. He noticed that the quantity of these radiations were nearly 3 times more at that altitude than what we get at the surface of the Earth. Astronomers from all over the world have tried their luck to solve this puzzle since then and it is a result of their findings that we know the composition of these radiations. Different subatomic particles including positively charged protons, negatively charged electrons, and atomic nuclei constitute these cosmic rays. Even the largest particle accelerators on Earth cannot match the energy and speed of these rays.

Despite the fact that quintillions of cosmic rays enter our atmosphere every second, it’s almost impossible to trace their sources. Once they collide with the atoms of the upper atmosphere, a cascade of secondary particles is created which moves rapidly towards Earth. Due to the presence of electric charge on these particles, their path changes whenever they encounter a magnetic field. As we know that space is full of such fields ranging from powerful magnetars to weak magnetic strength of Earth, quite a lot of distortion is available.

Just like the cosmic rays, massive amounts of neutrinos rain down on Earth every second but they are a whole lot more different when it comes to interacting with their surroundings. They are regarded as strange particles because they have hardly any mass and carry no charge. A neutrino makes no interaction at all during its journey through entire galaxies and this is the reason why scientists are able to trace its path back to the source. High energy neutrinos are generated by the same processes that accelerate the particles of the cosmic rays.

The IceCube Neutrino Observatory detected these neutrinos on 22nd Sep 2017. It automatically alerted all the other observatories about the existence of this particle within minutes. According to a statement from the Deutsches Elektronen-Synchroton in Germany, this information was imparted to all the observatories so that they could examine the region from where the neutrino had come. This ultimately led to the first-ever multimessenger observation of the merging of neutron stars. The information gathered from that event proved extremely beneficial for this recent discovery as the understanding of the scientists, about these superdense objects, got a massive boost.

The research team explained that the electromagnetic signals from gamma radiations to radio waves helped them to realize that the source of the neutrino is a supermassive black hole at the center of a galaxy which is at a distance of about 4 billion light years from Earth. The high-energy particles moving away from a black hole are called ‘Blazars’ and if the viewpoint of the astronomers is to be believed, one of them came rushing towards our planet at extreme speed. This finding came out as a shock to the scientific community. Francis Halzen, the Lead Scientist at the IceCube Neutrino Observatory, acknowledged that in the following words:

It is interesting that there was a general consensus in the astrophysics community that blazars were unlikely to be sources of cosmic rays, and here we are. Now, we have identified at least one source that produces high-energy cosmic rays because it produces cosmic neutrinos.”

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