[Paper Review] Multi-energy diffuse neutrino fluxes originating from core-collapse supernovae

Yosuke Ashida|arXiv (Cornell University)|Jan 22, 2024

Astrophysics and Cosmic Phenomena4 citations

TL;DR

This paper presents a unified framework for modeling diffuse neutrino fluxes from core-collapse supernovae (CCSNe) across multi-energy regimes, combining thermal MeV neutrinos from core collapse and non-thermal high-energy neutrinos from ejecta-circumstellar material interactions. By linking supernova types to progenitor masses via the Salpeter initial mass function and using cosmological simulations, it predicts that the diffuse high-energy neutrino flux could account for up to ~10% of the IceCube-observed astrophysical flux, while the diffuse supernova neutrino background (DSNB) remains near current Super-Kamiokande upper limits.

ABSTRACT

Diffuse neutrino fluxes attributed to two different physical processes in core collapse of massive stars are visited with their potentiality of exploring stellar physics more deeply being stressed. In this work, available models of thermal MeV-scale neutrinos produced at the core of collapsing stars and non-thermal high-energy neutrinos emitted from accelerated cosmic rays interacting with circumstellar material are bridged through features of core-collapse supernovae such as progenitor mass and optical properties. The calculated diffuse fluxes are presented with discussion about their detection prospects at neutrino telescopes.

Motivation & Objective

• To develop a comprehensive framework linking thermal MeV neutrinos from core collapse and non-thermal high-energy neutrinos from ejecta-CSM interactions in CCSNe.
• To bridge the gap between low-energy diffuse supernova neutrino background (DSNB) and high-energy astrophysical neutrino fluxes through a unified physical model.
• To quantify the diffuse neutrino flux contributions from different supernova types based on observational classifications and progenitor mass functions.
• To assess detection prospects at next-generation neutrino telescopes such as Hyper-Kamiokande, JUNO, IceCube-Gen2, and KM3NeT.

Proposed method

• Adopting a conventional supernova classification (Type II-L, II-P, IIn, IIb/Ibc) based on optical light curves and spectral features to assign progenitor mass ranges.
• Mapping supernova types to progenitor masses using the Salpeter initial mass function (IMF) for stars between 8.5–150 M☉, with 23.1 M☉ as a threshold.
• Modeling thermal neutrino fluxes from 15 M☉ and 40 M☉ progenitors for lighter and heavier SNe, respectively, based on core-collapse physics and neutrino emission mechanisms.
• Modeling non-thermal high-energy neutrino fluxes via pp interactions in circumstellar material, with distinct ejecta and CSM profiles for each SN type.
• Convoluting both neutrino flux components with the CCSN rate from the Illustris-1 cosmological simulation and the Chabrier IMF to compute the diffuse flux at Earth.
• Applying cosmological constants and redshift evolution to propagate fluxes to the present epoch for comparison with observational limits and detections.

Figure 1: Calculated DSNB $\bar{\nu}_{e}$ flux in comparison with experimental upper limits from Super-Kamiokande [ 43 , 44 ] and KamLAND [ 45 ] . Contributions from the CNS and HNS cases with $f_{\rm HNS}=0.24$ , and their sum are shown. The bands cover different choices of the nuclear EOS (LS220,

Experimental results

Research questions

• RQ1 How can thermal MeV neutrinos from core collapse and non-thermal high-energy neutrinos from ejecta-CSM interactions be consistently linked within a single framework for diffuse flux calculations?
• RQ2 What is the contribution of different supernova types (II-L, II-P, IIn, IIb/Ibc) to the total diffuse neutrino flux across MeV and GeV–TeV energy ranges?
• RQ3 To what extent can the observed high-energy astrophysical neutrino flux measured by IceCube be explained by CCSNe-originated non-thermal neutrinos?
• RQ4 How do uncertainties in black hole formation fraction and progenitor mass function affect the predicted diffuse neutrino fluxes?
• RQ5 What are the detectability prospects for these diffuse fluxes at upcoming neutrino telescopes like Hyper-Kamiokande and IceCube-Gen2?

Key findings

• The calculated diffuse supernova neutrino background (DSNB) for anti-electron neutrinos is consistent with the current Super-Kamiokande upper limit, within a factor of order one.
• The diffuse high-energy neutrino flux from CCSNe could account for up to approximately 10% of the astrophysical neutrino flux observed by IceCube.
• The DSNB flux is enhanced at higher energies (Eν ≳ 30 MeV) when including a non-zero black hole formation fraction, due to reduced low-energy contributions from failed SNe.
• The fluxes are sensitive to systematic factors such as the black hole formation fraction and progenitor mass function, which can alter the flux levels by orders of magnitude.
• The model predicts a non-trivial energy-dependent flux distribution that spans from MeV to TeV energies, enabling multi-messenger constraints on CCSN physics.
• Future detectors like JUNO and Hyper-Kamiokande are expected to improve sensitivity to the DSNB, while IceCube-Gen2 and KM3NeT will enhance the potential to probe high-energy CCSN neutrino contributions.

Figure 2: Calculated diffuse high-energy SN neutrino flux ( $\nu_{e}+\bar{\nu}_{e}+\nu_{\mu}+\bar{\nu}_{\mu}+\nu_{\tau}+\bar{\nu}_{\tau}$ ) in comparison with the measured diffuse astrophysical neutrino flux in a recent IceCube analysis using starting track events (ESTES) [ 85 ] . Contributions from