High-energy neutrinos are very fascinating subatomic particles that are produced when charged particles collide with other particles or photons very quickly. IceCube, a well-known neutrino detector at the South Pole, has been detecting extragalactic high-energy neutrinos for almost a decade.
While many physicists have examined the observations collected by the IceCube detector, the origin of most of the high-energy neutrinos detected has not yet been established. These neutrinos were detected outside our galaxy and may be the result of various cosmological events.
Researchers from Deutsches Elektronen Synchrotron DESY, Humboldt-Universität zu Berlin and other academic institutes in Europe and the US recently conducted a study that focuses on a specific violent cosmological event called AT2019fdr. Their paper, published in Physical Assessment Lettersshows that this event could be the origin of a high-energy neutrino.
“Our team conducted a systematic study over three years, using the Zwicky Transient Facility (ZTF) optical research telescope to scan the sky region of any new high-energy neutrino we can observe,” said Simeon Reusch, one of the researchers. researchers who conducted the study told Phys.org. “Our recent paper examines a possible source for one of these neutrinos, a massive optical burst in a very distant galaxy called AT2019fdr.”
AT2019fdr, the optical burst that Reusch and his colleagues studied, is a transient event, meaning it changes over time. The researchers studied this event in depth and tried to determine its possible source.
Based on their analyses, they concluded that AT2019fdr was most likely a tidal disturbance event (TDE). TDEs occur when a star approaches the supermassive black hole at the center of a galaxy and is close enough to be affected by it.
“As the star approaches the black hole, gravity The star’s front is much stronger than its back, tearing the star apart,” Reusch explained. “About half of the star’s mass then accumulates around the black hole, keeping the debris bright for months appears.”
Reusch and his colleagues also sought to determine whether AT2019fdr could be the possible origin of the high-energy neutrino they observed. For this they collaborated with theoretical physicists who could model the resource and make theoretical predictions based on their models.
“We tried to collect as much electromagnetic data on AT2019fdr as possible, covering a wide range of wavelengths,” Reusch said. “We observed the location and collected pre-existing data for it in radio, infrared, optical, UV, X-ray and gamma-ray wavelengths.”
In their analysis, the researchers assessed both the AT2019fdr event and other possible sources for the high-energy neutrino they observed, all of which were within reasonable proximity. Interestingly, they have excluded all sources, except AT2019fdr, because of their light curve (i.e. brightness profile over time) or because of the optical spectra they took.
“The strong dust echo we detected is in the infrared range, connecting AT2019fdr to a subclass of dust echo sources at the center of galaxies,” Reusch said. “The actual ‘echo’ is produced when the intense radiation from the TDE heats the surrounding dust, which then begins to glow in the infrared. The sheer size of the system causes delays due to the light’s travel times, which is why the peak of the dust echo is delayed relative to the flare.”
Reusch and his colleagues also observed a late X-ray signal with the eROSITA aboard the SRG satellite, with an extremely soft spectrum. Overall, both their measurements and theoretical analyzes point to AT2019fdr as the source of the high-energy neutrino they observed. In addition, the team’s findings suggest that AT2019fdr is a TDE and not a superluminous supernova, a “regular” outburst emanating from the center of the galaxy, or some other type of cosmological event.
“Our findings are remarkable, as an earlier paper by our group had already identified a TDE (AT2019fdr) as the likely source of another high-energy neutrino,” Reusch added. “If these TDEs were indeed both neutrino sources, they must be quite efficient at producing high-energy neutrinos† Multi-messenger studies such as those presented in our paper provide insight into cosmic particle accelerators such as TDEs or AGN that are not possible on the basis of photons alone.”
In their next studies, the researchers will conduct more analyzes to further validate their findings. In addition, they plan to search for other TDEs within the large dataset of cosmological events compiled by ZTF to date.
Simeon Reusch et al, Candidate Tidal Disruption Event AT2019fdr Coinciding with a high-energy neutrino, Physical Assessment Letters (2022). DOI: 10.1103/PhysRevLett.128.221101
Robert Stein et al, A tidal disturbance coinciding with a high-energy neutrino, Natural Astronomy (2021). DOI: 10.1038/s41550-020-01295-8
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Quote: Study identifies a tidal disruption coinciding with the production of a high-energy neutrino (June 2022, June 28), retrieved June 28, 2022 from https://phys.org/news/2022-06-tidal-disruption-event-coincides-production .html
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