Do high energy astrophysical neutrinos trace star formation?

TL;DR

This study investigates whether high energy astrophysical neutrinos detected by IceCube originate from starburst galaxies, finding a statistically significant excess of neutrino coincidences with these galaxies and superbubbles, suggesting they may contribute to the neutrino flux.

Contribution

The paper provides the first statistical analysis linking IceCube neutrinos to starburst galaxies and superbubbles, indicating a potential astrophysical source for the neutrinos.

Findings

Up to 8 coincidences with starburst galaxies observed.

Significant excess over null hypothesis with p=0.042.

Stronger correlation with gamma-ray-detected starbursts, p=0.003.

Abstract

The IceCube Neutrino Observatory has provided the first map of the high energy (~ 0.01 -- 1 PeV) sky in neutrinos. Since neutrinos propagate undeflected, their arrival direction is an important identifier for sources of high energy particle acceleration. Reconstructed arrival directions are consistent with an extragalactic origin, with possibly a galactic component, of the neutrino flux. We present a statistical analysis of positional coincidences of the IceCube neutrinos with known astrophysical objects from several catalogs. When considering starburst galaxies with the highest flux in gamma-rays and infrared radiation, up to n=8 coincidences are found, representing an excess over the ~4 predicted for the randomized, or "null" distribution. The probability that this excess is realized in the null case, the p-value, is p=0.042. This value falls to p=0.003 for a partial subset of gamma-ray-detected starburst galaxies and superbubble regions in the galactic neighborhood. Therefore, it is possible that starburst galaxies, and the typically hundreds of superbubble regions within them, might account for a portion of IceCube neutrinos. The physical plausibility of such correlation is discussed briefly.