Tomographic constraints on the high-energy cosmic neutrino emission rate

TL;DR

This work probes the extragalactic origin of high-energy neutrinos by cross-correlating IceCube's 10-year neutrino sky with four tomographic galaxy catalogs (z up to ~3). By modeling the neutrino emissivity and its redshift evolution, and using harmonic-space cross-correlations, the authors constrain the bias-weighted emissivity via three parametric models (power-law, star-formation-history peak, and tomographic) and a model-independent tomographic reconstruction. The analysis finds no significant correlation, yielding upper bounds on the emissivity combinations $Nb_\nu$ and $N_\rho b_\nu$ and per-redshift-bin limits on $b_\nu\dot{\bar{n}}_\nu$ and $b_\nu\dot{\bar{\rho}}_\nu$, with results robust to various systematics. The work demonstrates a novel method to test extragalactic neutrino source models and highlights the potential of future surveys (IceCube-Gen2, KM3NeT, LSST, Euclid) to turn tomographic neutrino–galaxy cross-correlations into precise probes of cosmic neutrino production across time.

Abstract

Despite growing efforts to find the sources of high energy neutrinos measured by IceCube, the bulk of the neutrinos remain with unknown origins. We aim to constrain the emissivity of cosmic high-energy neutrinos from extragalactic sources through their correlation with the large-scale structure. We use cross-correlations between the IceCube 10-year dataset and tomographic maps of the galaxy overdensity to place constraints on the bias-weighted high-energy neutrino emissivity out to redshift $z\sim3$. We test two different models to describe the evolution of neutrino emissivity with redshift, a power law model $\propto (1+z)^a$, and a model tracking the star formation history, assuming a simple power law model for the energy injection spectrum. We also consider a non-parametric reconstruction of the astrophysical neutrino emissivity as a function of redshift. We do not find any significant correlation, with our strongest results corresponding to a $1.9 σ$ deviation with respect to a model with zero signal. We use our measurements to place upper bounds on the bias-weighted astrophysical high-energy neutrino emission rate as a function of redshift for different source models. This analysis provides a new probe to test extragalactic neutrino source models. With future neutrino and galaxy datasets we expect the constraining and detection power of this type of analysis analysis to increase.

Figures (6)

• Figure 1: Neutrino intensity maps. The top panel displays the number-density-based map, the bottom panel displays the energy-density-based map (in GeV units).
• Figure 2: Redshift distributions of the four galaxy catalogues used here.
• Figure 3: Sky coverage of the four different galaxy catalogues used.
• Figure 4: Top panel: number-based neutrino-galaxy cross-correlation for the galaxy catalogues 2MPZ (green), WI $\times$ SC (yellow), DECaLS (red) and Quaia (magenta). Bottom panel, energy-based neutrino-galaxy cross-correlations for the same catalogues. A dashed black line it shown at $C_\ell = 0$ for guidance. The points for different catalogues are all shifted in $\ell$ for illustration purposes, but they all correspond to the $\ell$ where the 2MPZ values are shown.
• Figure 5: Allowed regions for the bias-weighted number density rate of neutrinos times in the two parametric models considered here (red and blue for the power law and peak models). We show the 1$\sigma$ and 2$\sigma$ constraints.