In November 2013 IceCube published its first evidence for the detection of astrophysical neutrinos. The paper resulted in IceCube receiving the Physics World Breakthrough of the Year award and much media coverage.

Until 2017, the cosmic neutrinos detected did not correlate with astrophysical sources or possible cosmic accelerators. This motivated IceCube to initiate an alert system whereby other astrophysical observatories, which detect other types of high-energy messengers such as gamma-rays, are notified when IceCube detects a cosmic neutrino. In 2017, such an alert led to the identification of the first ever known source of extragalactic cosmic rays: the blazar TXS 056+056. This discovery confirmed a longstanding belief amongst the scientific community that active galactic nuclei such as TXS 056+056 can act as cosmic ray accelerators.

An active galaxy is a galaxy where most of the radiation is not produced by stars but is due to material falling into a black hole millions of times more massive than our Sun and even more massive than the inactive black hole in the centre of our galaxy. Blazars are a particular type of active glaxy where the supermassive black-hole at the centre powers, through gravitational accretion, high-energy jets.

In 2022 another neutrino source was identified. In this case the identification was made by examining a large same of neutrinos detected by IceCube and examining the clustering of the neutrinos. The direction of the actice galactic nuclei NGC 1068 was seen to have a higher number neutrinos compared to what would be expected from a uniform background of neutrinos. NGC1068 is one of the most familiar and well-studied galaxies to date. First spotted in 1780, this galaxy, located 47 million light-years away from us, has a torus of nuclear dust which obscures most of the high-energy radiation produced by the dense mass of gas and particles that slowly spiral inward toward the center of the galaxy.