This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Astronomers have discovered that the jet of a distant blazar has been gravitationally lensed by an unseen source of dark matter. Led by Silke Britzen at the Max Planck Institute for Radio Astronomy in Germany, the team's results could prove especially important for observations of cosmic neutrinos, which are likely produced in abundance alongside a broad spectrum of electromagnetic waves in blazar jets.
If their interpretations are correct, they could help astronomers better understand the distant and mysterious origins of these chargeless, almost massless particles. Their results have been published in Monthly Notices of the Royal Astronomical Society. With its thousands of detectors embedded throughout a cubic kilometer of Antarctic ice, the IceCube Neutrino Observatory can detect the minute flashes of light produced when a cosmic neutrino interacts with the ice.
By tracing the paths of these flashes, astronomers can pinpoint the neutrinos' distant galactic origins. However, there is much we still don't understand about how these elusive particles are actually generated. One particularly enticing target for IceCube is a blazar named PKS 2233-148: an active galactic nucleus emitting jets of ionized matter from each pole, each traveling at close to the speed of light.
Crucially for astronomers, one jet is pointed directly into our line of sight. "These large-scale jets are cosmic accelerators, and might be generating neutrinos," Britzen explains. "We study them to search for any peculiarities which might help us to gain a better understanding of neutrino emission." To gain answers from these jets, researchers can't rely on IceCube's neutrino measurements alone.
Instead, they aim to identify cases where neutrino detections coincide with observations of electromagnetic waves generated in the same cosmic events. In their latest study, Britzen's team revisited high-resolution observations of PKS 2233-148 across the electromagnetic spectrum, including radio observations by the Very Long Baseline Array (VLBA), a network of dishes spread across the U.S.; gamma-ray observations by the Fermi-LAT space telescope; and X-ray detections from the Swift-XRT observatory. From these combined measurements, the researchers could then precisely determine the motion of the blazar's jet and its variation over time.
The analysis yielded a promising result. "We are very happy to have discovered as-yet-undetected phenomena in the jet, as well as in the gamma-ray light curve," Britzen says. Most importantly, the measurements revealed that PKS 2233-148's jet had been suddenly displaced from its expected path.
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