First identification of an astronomical source for a high-energy neutrino

For the first time scientists were able to trace the source of a high-energy neutrino, a very low mass elementary particle that weakly interacts with matter, that was detected via the IceCube neutrino observatory [1], [2]. Promptly after the detection an extensive multiwavelength campaign followed in order to trace the emission source. The event was coincident with a blazar, an active galactic nucleus emitting a relativistic jet directed towards the Earth, 3.8 Giga light years from us. In addition, the IceCube team investigated 9.5 years of observations and found excess emission at the position of the blazar. Their findings show, for the first time, that blazars may be sources of high-energy astrophysical neutrinos.

 

In a report by the Israeli Space Agency [3] professor Ehud Behar, Dean of the physics department at the Technion and the former head of the Technion Asher Space Research Institute (who is not part of the detection in subject), explains that “until today the high-energy neutrino sources were not traced back to known astronomical sources, in other words when observing in the direction of the neutrinos no known astronomical source has been identified, to which the neutrino can be attributed. The present neutrino event is the first time electromagnetic emission (measured in the follow up observations) has been connected to high-energy neutrinos”. He further points out that this detection indicates that super massive black holes (centered in active galactic nuclei) accelerate the most energetic neutrinos, as well as the protons that produce them. These high-energy protons are termed cosmic rays, and they have been measured on Earth for over a century though their origin has so far been a mystery. This new discovery proves that such super massive black holes (“blazars”) are capable of accelerating cosmic rays to energies of 1015 eV and higher.

 

For the IceCube press release  (https://icecube.wisc.edu)

 

References:
[1] Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A

[2] Ice reveals a messenger from a blazing galaxy

[3] עידן חדש באסטרונומיה: זוהה "חלקיק רפאים" באנטארקטיקה שמקורו בחור שחור

 

 

GRAPHIC:
GRANT ET AL., SCIENCE, VOL. 361, 147 (2018) ADAPTED BY C. BICKEL/SCIENCE
(http://science.sciencemag.org/content/361/6398/115.full)