IceCube-Gen2: A Vision for the Future of Neutrino Astronomy in Antarctica

TL;DR

IceCube demonstrated a cosmic neutrino flux, signaling powerful hadronic accelerators in the non-thermal universe. The paper outlines IceCube-Gen2, a 10 km^3 high-energy array designed to boost event rates, improve angular and energy resolution, and enable detailed source localization, GZK neutrino detection, and multi-messenger studies. It details design choices, including increased string spacing, extended string length, advanced DOM electronics, and modular drilling, as well as veto strategies and surface/radio extensions that broaden the energy reach. The proposed Gen2 facility is positioned to become the leading instrument for neutrino astronomy, with broad physics goals spanning astrophysics, cosmology, and beyond-the-Standard-Model physics.

Abstract

The recent observation by the IceCube neutrino observatory of an astrophysical flux of neutrinos represents the "first light" in the nascent field of neutrino astronomy. The observed diffuse neutrino flux seems to suggest a much larger level of hadronic activity in the non-thermal universe than previously thought and suggests a rich discovery potential for a larger neutrino observatory. This document presents a vision for an substantial expansion of the current IceCube detector, IceCube-Gen2, including the aim of instrumenting a $10\,\mathrm{km}^3$ volume of clear glacial ice at the South Pole to deliver substantial increases in the astrophysical neutrino sample for all flavors. A detector of this size would have a rich physics program with the goal to resolve the sources of these astrophysical neutrinos, discover GZK neutrinos, and be a leading observatory in future multi-messenger astronomy programs.

Figures (12)

• Figure 1: Schematic of the IceCube detector.
• Figure 2: Anticipated astrophysical neutrino fluxes produced by supernova remnants and GRBs exceed the atmospheric neutrino flux in IceCube above 100 TeV because of their relatively hard $E^{-2}$ spectrum. Also shown is a sample calculation of the GZK neutrino flux. The atmospheric electron-neutrino spectrum (green open triangles) is from Aartsen:2013rt. The conventional $\nu_e$ (red line) and $\nu_\mu$ (blue line) from Honda, $\nu_e$ (red dotted line) from Bartol and charm-induced neutrinos (magenta band) Enberg:2008te are shown. Previous measurements from Super-K GonzalezGarcia:2006ay, Frejus Daum:1994bf, AMANDA Abbasi:2009nfaAbbasi:2010qv and IceCube Abbasi:2010ieAbbasi:2011jx are also shown. Details about the theoretical estimates shown can be found in Ref. Halzen:2013bta.
• Figure 3: Deposited energies of events observed in 3 years of data with predictions. The hashed region shows uncertainties on the sum of all backgrounds. Muons (red) are computed from simulation to overcome statistical limitations in our background measurement and scaled to match the total measured background rate. Atmospheric neutrinos and uncertainties thereon are derived from previous measurements of both the $\pi, K$ and charm components of the atmospheric spectrum Aartsen:2013vca. A gap larger than the one between 400 and 1000 TeV appears in 43% of realizations of the best-fit continuous spectrum.
• Figure 4: Spectrum of secondary muons initiated by muon neutrinos that have traversed the Earth, i.e., with zenith angle less than $5^\circ$ above the horizon, as a function of the energy deposited inside the detector, used here as a proxy for the muon energy. The highest energy muons are, on average, initiated by PeV neutrinos.
• Figure 5: Joint fit to the highest energy extragalactic photon flux (red) observed by Fermi and the astrophysical neutrino flux (black) observed by IceCube. The fit assumes that the decay products of neutral and charged pions from $pp$ interactions are responsible for the non-thermal emission in the Universe Murase:2013rfa. The thin lines represent an attempt to minimize the contribution of the pionic gamma ray flux to the Fermi observations. It assumes an injected flux of $E^{-2}$ with exponential cutoff at low and high energy. The black data points are measured by the IceCube 3-year "High-Energy Starting Event" ("HESE") analysis Aartsen:2014gkd, the gray data points are from an IceCube analysis lowering the energy threshold for events starting in the detector even further Aartsen:2014muf.