Diffuse PeV neutrino emission from Ultra-Luminous Infrared Galaxies

TL;DR

This paper models how ultra-luminous infrared galaxies produce high-energy PeV neutrinos through hypernova-driven cosmic ray acceleration and interactions, estimating their contribution to the diffuse neutrino background.

Contribution

It provides the first detailed estimate of PeV neutrino flux from ULIRGs based on their starburst activity and hypernovae, linking galaxy properties to neutrino production.

Findings

ULIRGs can produce neutrinos up to 5 PeV via hypernova shocks.

The diffuse neutrino flux from ULIRGs is comparable to atmospheric neutrinos at PeV energies.

ULIRGs contribute significantly to the high-energy neutrino background.

Abstract

Ultra-luminous infrared galaxies (ULIRGs) are the most luminous and intense starburst galaxies in the Universe. Both their star-formation rate (SFR) and gas surface mass density are very high, implying a high supernovae rate and an efficient energy conversion of energetic protons. A small fraction of these supernovae is the so-called hypernovae with a typical kinetic energy ~1e52 erg and a shock velocity >=1e9 cm/s. The strong shocks driven by hypernovae are able to accelerate cosmic ray protons up to 1e17 eV. These energetic protons lose a good fraction of their energy through proton-proton collision when ejected into very dense interstellar medium, and as a result, produce high energy neutrinos (<=5 PeV). Recent deep infrared surveys provide solid constraints on the number density of ULIRGs across a wide redshift range 0<z<2.3, allowing us to derive the flux of diffuse neutrinos from hypernovae. We find that at PeV energies, the diffuse neutrinos contributed by ULIRGs are comparable with the atmosphere neutrinos with the flux of 2e-9GeV cm^-2/s/sr, by assuming the injected cosmic ray power law spectrum with an index of -2.