IceCube-Gen2: The Window to the Extreme Universe (2008.04323v1)

Abstract: The observation of electromagnetic radiation from radio to $\gamma$-ray wavelengths has provided a wealth of information about the universe. However, at PeV (10$^{15}$ eV) energies and above, most of the universe is impenetrable to photons. New messengers, namely cosmic neutrinos, are needed to explore the most extreme environments of the universe where black holes, neutron stars, and stellar explosions transform gravitational energy into non-thermal cosmic rays. The discovery of cosmic neutrinos with IceCube has opened this new window on the universe. In this white paper, we present an overview of a next-generation instrument, IceCube-Gen2, which will sharpen our understanding of the processes and environments that govern the universe at the highest energies. IceCube-Gen2 is designed to: 1) Resolve the high-energy neutrino sky from TeV to EeV energies; 2) Investigate cosmic particle acceleration through multi-messenger observations; 3) Reveal the sources and propagation of the highest energy particles in the universe; 4) Probe fundamental physics with high-energy neutrinos. IceCube-Gen2 will increase the annual rate of observed cosmic neutrinos by a factor of ten compared to IceCube, and will be able to detect sources five times fainter than its predecessor. Furthermore, through the addition of a radio array, IceCube-Gen2 will extend the energy range by several orders of magnitude compared to IceCube. Construction will take 8 years and cost about \$350M. The goal is to have IceCube-Gen2 fully operational by 2033. IceCube-Gen2 will play an essential role in shaping the new era of multi-messenger astronomy, fundamentally advancing our knowledge of the high-energy universe. This challenging mission can be fully addressed only in concert with the new survey instruments across the electromagnetic spectrum and gravitational wave detectors which will be available in the coming years.

• The paper presents IceCube-Gen2’s improved detection capability, increasing neutrino counts by a factor of ten.
• It outlines an innovative design with an expanded optical array and radio detectors to capture neutrinos up to EeV energies.
• Enhanced veto strategies and multi-messenger integration enable probing of fundamental physics and astrophysical particle acceleration.

Overview of the IceCube-Gen2 Proposal

The paper outlines the design and scientific motivations for the IceCube-Gen2 neutrino observatory, which is proposed as an enhancement over the existing IceCube detector at the South Pole. IceCube-Gen2 aims to increase the annual neutrino detection rate by a factor of ten compared to IceCube and extend the energy range of detected neutrinos up to the EeV scale. This enhancement will allow for the investigation of more sources and improve our understanding of high-energy cosmic phenomena.

Key Objectives of IceCube-Gen2

IceCube-Gen2 is designed to tackle four primary scientific goals:

1. Resolve the High-Energy Neutrino Sky: The detector will cover energies from TeV to EeV, offering an improved sensitivity to point sources by a factor of five. This will enable the elucidation of processes occurring in the most extreme environments, such as those close to black holes and neutron stars.
2. Investigate Cosmic Particle Acceleration: By integrating multi-messenger observations, IceCube-Gen2 will provide insights into the mechanisms driving particle acceleration in astrophysical sources.
3. Explore the Sources and Propagation of the Highest-Energy Particles: The observatory will probe both Galactic and extragalactic cosmic rays, elucidating their sources and the propagation through interstellar and intergalactic media.
4. Probe Fundamental Physics with Neutrinos: High-energy neutrinos from IceCube-Gen2 will allow for tests of neutrino interactions beyond the capabilities of current terrestrial experiments, potentially revealing new physics.

The Design and Enhancements

IceCube-Gen2's design focuses on increasing the instrumented volume to nearly 8 km³, achieved by deploying additional strings of photomultiplier modules deeper and further spaced than in the current IceCube configuration. The addition of a radio detector array will also extend sensitivity to neutrinos at ultra-high energies above 100 PeV.

Key Design Aspects Include:

• Expanded Optical Array: This component will contain more densely packed optical sensors, enhancing sensitivity to all neutrino flavors across a broad energy range.
• Radio Detection Array: Capable of detecting the radio frequencies generated by high-energy neutrino interactions, this component increases sensitivity at the highest energies.
• Enhanced Veto Strategy: A surface array will improve the rejection of atmospheric muons and neutrinos, enhancing the purity of detected astrophysical neutrinos.

Scientific Implications

The enhancements provided by IceCube-Gen2 will significantly impact the field of neutrino astronomy and multi-messenger astrophysics:

• Improved Source Sensitivity: The ability to pinpoint astrophysical sources with higher accuracy will facilitate discoveries in high-energy astrophysics.
• Neutrino and Cosmic Ray Synergies: By studying both particles, IceCube-Gen2 will bridge the gap between neutrino astronomy and cosmic ray physics.
• Test of Astrophysical Models: Improved statistics and energy ranges will enable testing and refinement of models of cosmic particle acceleration and interaction.

Future Prospects

IceCube-Gen2 is set to play a crucial role in the emerging era of multi-messenger astronomy, collaborating with other global facilities for electromagnetic and gravitational wave detections. As the most sensitive neutrino observatory proposed, it promises to provide unprecedented insights into the high-energy universe and fundamental physics. This ambitious project will require significant financial investments, estimated at approximately $350 million, and a construction timeline extending over several years to reach full operation by 2033.