About 100,000 million years ago, a tiny subtomic particle formed in a distant galaxy and began its journey across the vast expanse of our universe. That neutrino finally reached the Earth’s south pole last October, closing the detector buried under the Antarctic ice. A few months ago, a telescope in California noticed a bright glow, evidence of a so-called “tidal disturbance phenomenon” (TDE), possibly the result of a star being cut by a supermassive black hole.
According to two new papers published here (here and here) in the journal Nature Astronomy, neutrinos alone may have originated from TDE, which serves as a cosmic scale particle accelerator near the center of a distant galaxy, carving out high-energy subtomics. Particles as star matter are eaten by black holes. The discovery will also shed light on the origin of ultra-high-energy cosmic rays, a question that has puzzled astronomers for decades.
“The purpose of cosmic high-energy neutrinos is unknown, mainly because they are difficult to decipher in a notable way,” said Joert Van Wells, a post-doc at New York University during the search. “This will be only the second time high-energy neutrinos have been traced to their source.”
Neutrinos travel very close to the speed of light. John Updecki’s 1959 poem, “Cosmic Gail”, pays homage to the two most defined features of neutrinos: they have no charge and, for decades, physicists have believed they have no mass (they have really trivial matter). The neutrino is the most abundant subtomic particle in the universe, but it rarely interacts with any part of matter. These millions of tiny particles are constantly bombarded by us every second, even though they pass through us without our attention. That’s why Isaac Asimov called them “ghost particles.”
That low rate of interaction makes neutrinos extremely difficult to detect, but because they are so light, they can escape uncontrollably (and thus largely unchanged) from colliding with other particles of matter. This means they can provide valuable clues to astronomers about distant systems, further enhanced by the electromagnetic spectrum, as well as what can be learned with telescopes of gravitational waves. Also, these differentiated sources of information have been called “multi-messenger” astronomy.
Most of the neutrinos that reach Earth come from our own sun, but even now neutrino detectors prefer the rare neutrinos that are at the front. This is the case in the latest investigation: a neutrino that began its journey from afar, as the constellation Delphinus still has an anonymous galaxy, born from the death of a truncated star.
DESY, Science Communication Lab
As we noted earlier, it is a popular misconception that black holes behave like cosmic vacuum cleaners, sucking anything around them wildly. In reality, only material moving beyond the event horizon, including light material, swallows and cannot escape, although black holes are also cluttered eaters. This means that part of an object’s object is actually ejected in a powerful jet. If it is an object star, the process of slipping (or “spaghettiified”) by the powerful gravitational forces of a black hole takes place outside the event horizon, and part of the star’s core mass is violently pulled out. This in turn can create a rotating ring (aka an action disc) of matter around the black hole that emits powerful X-rays and visible light.
Tidal disturbances describe large forces created when a small body moves too close to a large one, such as a star that stays very close to a supermassive black hole. “The force of gravity becomes stronger and stronger as you get closer. This means that the gravity of a black hole pulls closer to the nearest side of the star, leading to a gravitational effect,” said Robert Stein, co-author of DESY. In Germany. “As the star gets closer, the pull intensifies. Eventually it snatches the star away, and then we call it a tidal disruption event. This is the same process that leads to ocean tides on Earth, but Luckily for us, the moon doesn’t ‘pull hard enough to slice the earth.’
Although TDEs are probably common in our universe, only a few have been discovered so far. For example, in 2018, astronomers announced the first direct image of a star cut through a black hole 20 million times larger than our Sun, in a pair of colliding galaxies called Arp 299, about 150 million light-years from Earth. And last fall, astronomers noted the final death throes of a star cut through a supermassive black hole, highlighting discoveries in Nature Astronomy.
The flash of this most recent TDE was first discovered on April 9, 2019 by the Zwicky Transit Facility (ZTF) at the Mount Palomer Observatory in California, which has detected more than 30 such incidents since the arrival of the 2018 line. About five months later, on October 1, 2019, the IceCube Neutrino Observatory at the South Pole recorded an indication of highly get neutrinos emanating from a direction similar to TDD. How strong was he? Anna Francovik, co-author of DSY, created the raja at more than 100 teraelectronvolts (TEVs), 10 times the maximum energy raja of subatomic particles that can be generated by a large hadron collider.
Ice Cube / NSF
The probability of finding these isolated high-voltage neutrinos was only 1 in 500. “This is the first neutrino to be associated with the occurrence of tidal disturbances, and it brings valuable evidence for us,” Stein said. “Incidents of tidal fractures are not well understood. Neutrino probes point to the existence of a central, powerful engine near the acidification disc, emitting fast particles .And the combined analysis of data from radio, optical and ultraviolet telescopes gives us additional opportunities. That TDA acts as a giant particle accelerator. “
It is yet another example of the new knowledge of combining multiple data sources to get different perspectives on the same celestial phenomenon. “Combined observations demonstrate the power of multi-messenger astronomy,” said Merek Kowalski, co-author of DESY in Berlin and Humboldt University. “Without investigating the tidal rupture event, the neutrino would be one of many. And without the neutrino, the observation of the tidal disruption event would be just one of many. Only through combination will we be able to find acceleration and learn something new about the processes inside.”
Speaking of the future, “we’ll just see the top of the iceberg here. In the future, we expect a lot more associations between high-energy neutrinos and their sources,” said Francis Hulzen of the University of Wisconsin-Madison. Which was not directly involved in the study. “A new pay generation of telescopes is being built that will provide greater sensitivity to TDE and other potential neutrino sources. The planned expansion of the icecube neutrino detector will increase the number of global neutrino probes by at least tenfold.”
DOI: Nature Astronomy, 2021. 10.1038 / s41550-020-01295-8
DOI: Nature Astronomy, 2021. 10.1038 / s41550-021-01305-3 (About DOI).
