Milky Way as a Neutrino Desert Revealed by IceCube Galactic Plane Observation

Abstract

The Galactic diffuse emission (GDE) is formed when cosmic rays leave the sources where they were accelerated, diffusively propagate in the Galactic magnetic field, and interact with the interstellar medium and interstellar radiation field. GDE in $\gamma$-ray (GDE-$\gamma$) has been observed up to sub-PeV energies, though its origin may be explained by either cosmic-ray nuclei or electrons. We show that the $\gamma$-rays accompanying the high-energy neutrinos recently observed by the IceCube Observatory from the Galactic plane have a flux that is consistent with the GDE-$\gamma$ observed by the {\it Fermi}-LAT and Tibet AS$\gamma$ experiments around 1 TeV and 0.5 PeV, respectively. The consistency suggests that the diffuse $\gamma$-ray emission above $\sim$1TeV could be dominated by hadronuclear interactions, though partial leptonic contribution cannot be excluded. Moreover, by comparing the fluxes of the Galactic and extragalactic diffuse emission backgrounds, we find that the neutrino luminosity of the Milky Way is one to two orders of magnitude lower than the average of distant galaxies. This implies that our Galaxy has not hosted the type of neutrino emitters that dominates the isotropic neutrino background at least in the past few tens of kiloyears.

20 pages, 2 figures + Supplemental Material. Accepted for publication in Nature Astronomy

References in corpus (24)

• The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
• Evidence for neutrino emission from the nearby active galaxy NGC 1068
• The IceCube high-energy starting event sample: Description and flux characterization with 7.5 years of data
• The Spectrum and Morphology of the Fermi Bubbles
• Observation of high-energy neutrinos from the Galactic plane
• Improved Characterization of the Astrophysical Muon-Neutrino Flux with 9.5 Years of IceCube Data
• Detection of large-scale X-ray bubbles in the Milky Way halo
• Cosmic-ray propagation with DRAGON2: I. numerical solver and astrophysical ingredients
• The Evolution of Galaxy Number Density at z < 8 and its Implications
• No significant evolution of relations between Black hole mass and Galaxy total stellar mass up to z~2.5
• Measurement of ultra-high-energy diffuse gamma-ray emission of the Galactic plane from 10 TeV to 1 PeV with LHAASO-KM2A
• High-Energy Gamma Rays from the Milky Way: Three-Dimensional Spatial Models for the Cosmic-Ray and Radiation Field Densities in the Interstellar Medium
• Probing the Fermi Bubbles in Ultraviolet Absorption: A Spectroscopic Signature of the Milky Way's Biconical Nuclear Outflow
• Nuclear Outflow of the Milky Way: Studying the Kinematics and Spatial Extent of the Northern Fermi Bubble
• The Interaction of the Fermi Bubbles with the Milky Way's Hot Gas Halo
• Fermi and eRosita bubbles as relics of the past activity of the Galactic black hole
• The large-scale ionization cones in the Galaxy
• A signature of anisotropic cosmic-ray transport in the gamma-ray sky
• The TeV Diffuse Cosmic Neutrino Spectrum and the Nature of Astrophysical Neutrino Sources
• Galactic diffuse gamma rays meet the PeV frontier
• Diffuse Emission of Galactic High-Energy Neutrinos from a Global Fit of Cosmic Rays
• Unresolved sources naturally contribute to PeV $\gamma$-ray diffuse emission observed by Tibet AS$\gamma$
• The gamma-ray / infrared luminosity correlation of star-forming galaxies
• The contribution of Galactic TeV pulsar wind nebulae to Fermi-LAT diffuse emission

Cited by in corpus (9)

• Insights from LHAASO and IceCube into the origin of the Galactic diffuse TeV--PeV emission
• A proposed deep sea Neutrino Observatory in the Nanhai
• Extended TeV Halos May Commonly Exist around Middle-Aged Pulsars
• Absence of TeV halos around millisecond pulsars
• Estimatingthe Contribution of Galactic Neutrino Sources
• The Cosmic-ray Knee as a Local Signature of Nearby PeVatrons
• Particle Astrophysics with High and Ultrahigh Energy Neutrinos
• The potential of diffuse Galactic Ridge neutrino measurements to constrain dark matter
• TeV-PeV Gamma-ray and Neutrino Emission in the Galactic Plane