Scientists have discovered a giant space particle accelerator

Neutrino gives a remarkable view of the generally hidden mechanism of particle acceleration in astrophysical objects. The IceCube Collaboration recently discovered the possible relationship of a single-energy neutrino to a torch from a relativistic jet of an active galaxy directed toward Earth.

Recently, scientists from ICRAR found a neutrino to such a ‘tidal disorder event’ (TDE). The team reported that these little-understood cosmic catastrophes could be powerful natural particle accelerators.

A subatomic particle, called a neutrino, was thrown toward Earth after a doomed star disintegrated too close to a supermassive black hole at the center of its parent galaxy by the huge gravity of a black hole.

This study helps scientists understand the power of space exploration using a combination of different ‘messengers’ such as photons (light particles) and neutrinos, also known as multi-messenger astronomy.

Co-author Marek Kowalski, head of neutrino astronomy at DESY and a professor at Humboldt University in Berlin, said, “Combined observations show the power of multi-messenger astronomy. Without detecting the events of tidal disorders, a neutrino would be just one of many. And without neutrinos, observing the events of tidal disorders would be just one of many. Only with the help of a combination could we find an accelerator and learn something new about the processes in them. “

The neutrino tracked by the scientists traveled 700 million years from a distant, unnamed galaxy in the constellation Delphinus (Dolphin) to finally reach the IceCube neutrino detector at the South Pole. According to scientists, the supermassive black hole that launched this neutrino must be as huge as 30 million suns.

In this artistic display, based on an actual image of the IceCube lab at the South Pole, a remote source emits neutrinos that are detected under ice using an IceCube sensor, called a DOM. Credits: IceCube / NSF

Principal author Robert Stein, a DESY scientist, said, “The force of gravity is getting stronger and stronger as you get closer to something. This means that the gravity of the black hole attracts the near side of the star more strongly than the far side of the star, which leads to the effect of stretching. This difference is called the tidal force, and as the star approaches, that stretching becomes more extreme. Eventually the star disintegrates, and then we call it a tidal disorder. It is the same process that leads to ocean tides on Earth, but fortunately, the moon does not pull enough to destroy the Earth. “

On October 1, 2019, the IceCube neutrino detector at the South Pole registered an extremely energetic neutrino from the direction of the tidal disorder event. Extremely light neutrinos communicate with almost nothing, pass imperceptibly not only through walls but through entire planets or stars, and are often called ghosts.

Scientists have noticed “Even catching just one high-energy neutrino is already an extraordinary observation. The detection prompted further observations of events with many instruments across the entire electromagnetic spectrum, from radio waves to X-rays.

ICRAR-Curtin professor James Miller said, “It seems that not all events of tidal disorders produce such an energy outflow. Therefore, radio detection of this event provided important evidence that it was probably a source of neutrinos. “

Lead author Robert Stein explains it “This is the first neutrino associated with the event of tidal disorders and brings us valuable evidence. The events of tidal disorders are not well understood. Neutrino detection indicates the existence of a central, powerful motor near the accretion disk that emits fast particles. And the combined analysis of data from radio, optical and ultraviolet telescopes gives us additional evidence that TDE acts as a giant particle accelerator. “

Francis Halzen, a professor at the University of Wisconsin-Madison and chief investigator of IceCube, who was not directly involved in the study, said, “Maybe we only see the tip of the iceberg here. In the future, we expect to find many more associations between high-energy neutrinos and their sources. A new generation of telescopes will be built that will provide greater sensitivity to TDE and other future neutrino sources. Even more important is the planned expansion of the IceCube neutrino detector, which would increase the number of cosmic neutrino detections at least tenfold. “

Professor Miller-Jones said, “It is fascinating that the expertise of the radio astronomy of astronomical astronomers has a key role in discovering these new insights into the high-energy universe. The huge jump in sensitivity provided by a square kilometer will allow detailed studies of several of these cataclysmic events. This will provide a new critical insight into the operation of black holes. “

The IceCube Neutrino Observatory is a facility of the U.S. National Science Foundation operating at the South Pole station of Amundsen-Scott as part of the U.S. Antarctic Program. In addition to IceCube and ZTF, instruments Spectrum Power Distribution Machine (SEDM), Palomar 200-inch Telescope Hale (P200), Liverpool Telescope (LT), NASA’s Neil Gehrels Fast Observatory, Lowell Discovery Telescope, Line Observatory Shane Telescope, Keck telescope ESA’s multi-mirror X-ray mission (XMM-Newton), Karl G. Jansky very large array (VLA), AMI large array (AMI-LA), MeerKAT and NASA’s large Fermi telescope Fermi-LAT ) provided observation data. for the study.

Journal reference:
  1. Robert Stein, Sjoert van Velzen, Marek Kowalski et al. A tidal disturbance event that coincides with a high-energy neutrino. Astronomy of Nature, 2021, DOI: 10.1038 / s41550-020-01295-8