Further evidence for an increase of the mean mass of the highest-energy cosmic-rays with energy

Watson, Alan

doi:10.1016/j.jheap.2021.11.001

Cited by 10 publications

(14 citation statements)

References 10 publications

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“…Nearly all published data are consistent with the description of having a steep rate up to an apparent change to a flatter rate in the vicinity of 3 EeV. This transition supports the growing evidence of a transition from a lighter proton dominated composition to a heavier composition as energy climbs [196,197] in both hemispheres.…”

Section: Primary Composition Above 1 Eevsupporting

confidence: 83%

“…The duty cycle of the fluorescence technique and the suppressed flux at the highest energies prevents measurements of mass beyond 50 EeV with current statistics. While the determination of the average mass of the primary nuclei is uncertain and events detected with Telescope Array have not confirmed an intermediate mass in the 30 − 80 EeV range, they do confirm the observed change in the elongation rate [196] which is considered a quite robust evidence of a composition change [197], unless the cross sections involved have dramatic deviations from Standard Model predictions.…”

Section: Correlations With the Arrival Directions: Uhecr As Messengersmentioning

confidence: 79%

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Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

Coleman,

Eser,

Mayotte

et al. 2022

Preprint

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Pin down the shower energy observable to use μ as a composition-only Reduce hadronic uncertainties interaction model E threshold (TBD) Other messengers Galactic * μ / em separation † * depending on analysis progress † depending on detector configuration• At least one next-generation experiment needs to be able to make high-precision measurements to explore new particle physics and measure particle rigidity on an event-by-event basis. Of the planned next-generation experiments, GCOS is the best positioned to meet this recommendation.• As a complementary effort, experiments with sufficient exposure ( 5 × 10 5 km 2 sr yr) are needed to search for Lorentz-invariance violation (LIV), SHDM, and other BSM physics at the Cosmic and Energy Frontiers, and to identify UHECR sources at the highest energies.• Full-sky coverage with low cross-hemisphere systematic uncertainties is critical for astrophysical studies. To this end, next generation experiments should be space-based or multi-site. Common sites between experiments are encouraged.• Based on the productive results from inter-collaboration and inter-disciplinary work, we recommend the continued progress/formation of joint analyses between experiments and with other intersecting fields of research (e.g., magnetic fields).• The UHECR community should continue its efforts to advance diversity, equity, inclusion, and accessibility. It also needs to take steps to reduce its environmental impacts and improve open access to its data to reduce the scientific gap between countries.vi

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Section: Primary Composition Above 1 Eevsupporting

confidence: 83%

Section: Correlations With the Arrival Directions: Uhecr As Messengersmentioning

confidence: 79%

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

Coleman,

Eser,

Mayotte

et al. 2022

Preprint

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“…Other important dependencies come from the maximum acceleration energy of the cosmic rays at the sources, the shape of the energy spectrum of the accelerated particles, and the cosmological evolution of the sources. As a consequence of the various progresses made over time to constrain these quantities, flux predictions at 10 18 eV went from fairly high values, namely energy fluxes up to E 2 f ν ; 10 −9 GeV cm −2 sr −1 s −1 , obtained for a vanilla pure-proton composition to much lower ones, namely E 2 f ν ; 10 −12 GeV cm −2 sr −1 s −1 , in the framework of a mixed composition model much more in line with the various constraints inferred from the data collected at the Pierre Auger Observatory (Aab et al 2014a(Aab et al , 2014bTkachenko et al 2023) and in other experiments (Watson 2022).…”

Section: Introductionsupporting

confidence: 81%

Floor of Cosmogenic Neutrino Fluxes above 10¹⁷ eV

Bérat,

Condorelli,

Deligny

et al. 2024

ApJ

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The search for neutrinos with energies greater than 1017 eV is being actively pursued. Although normalization of the dominant neutrino flux is highly uncertain, a floor level is guaranteed by the interactions of extragalactic cosmic rays with milky Way gas. We estimate that this floor level gives an energy flux of E 2 ϕ ν ≃ 10 − 13 − 0.5 + 0.5 GeV cm − 2 sr − 1 s − 1 at 1018 eV, where uncertainties arise from the modeling of the gas distribution and the experimental determination of the mass composition of ultra–high-energy cosmic rays on Earth. Based on a minimal model of cosmic-ray production to explain the mass-discriminated energy spectra observed on Earth above 5 × 1018 eV, we also present generic estimates of the neutrino fluxes expected from extragalactic production that generally exceed the aforementioned guaranteed floor. The prospects for detecting neutrinos above 1018 eV remain challenging, however, unless proton acceleration to the highest energies is at play in a subdominant population of cosmic-ray sources or new physical phenomena are at work.

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“…Following this principle, several studies have laid the foundations for a generic scenario that broadly reproduces the observations (Allard et al 2008;Aloisio et al 2014;Taylor et al 2015;Aab et al 2017b;Zhang et al 2018;Guido & Pierre Auger Collaboration 2021). The intensity of the individual nuclear components at the sources, generally considered as stationary and uniformly distributed in a comoving volume, is assumed to drop off at the same magnetic rigidity so as to explain the gradual increase with energy of the mass number A observed on Earth (Abraham et al 2010;Aab et al 2014a;Watson 2022). This is consistent with the basic expectation that electromagnetic processes accelerate particles up to a maximum energy proportional to their electric charge Z.…”

Section: Introductionmentioning

confidence: 61%

Observational Constraints on Cosmic-Ray Escape from Ultrahigh-energy Accelerators

Luce

Marafico

Biteau

et al. 2022

ApJ

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Interactions of ultra-high energy cosmic rays (UHECRs) accelerated in specific astrophysical environments have been shown to shape the energy production rate of nuclei differently from that of the secondary neutrons escaping from the confinement zone. Here, we aim at testing a generic scenario of in-source interactions through phenomenological modeling of the flux and composition of UHECRs. We fit a model in which nucleons and nuclei follow different particle energy distributions to the all-particle energy spectrum and proton spectrum below the ankle energy and distributions of maximum shower depths above this energy, as inferred at the Pierre Auger Observatory. We obtain that the data can be reproduced using a spatial distribution of sources that follows the density of extragalactic matter on both local and large scales, providing hence a realistic set of constraints for the emission mechanisms in cosmic accelerators, for their energetics, and for the abundances of elements at escape from their environments. While the quasi monoelemental increase of the cosmic-ray mass number observed on Earth from ≃2 EeV up to the highest energies calls for nuclei accelerated with a hard spectral index, the inferred flux of protons down to ≃0.6 EeV is shown to require for this population a spectral index significantly softer than that generally obtained up to now. We demonstrate that modeling UHECR data across the ankle substantiates the conjecture of in-source interactions in a robust statistical framework, although pushing the mechanism to the extreme.

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Further evidence for an increase of the mean mass of the highest-energy cosmic-rays with energy

Cited by 10 publications

References 10 publications

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

Floor of Cosmogenic Neutrino Fluxes above 10¹⁷ eV

Observational Constraints on Cosmic-Ray Escape from Ultrahigh-energy Accelerators

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Further evidence for an increase of the mean mass of the highest-energy cosmic-rays with energy

Cited by 10 publications

References 10 publications

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

Floor of Cosmogenic Neutrino Fluxes above 1017 eV

Observational Constraints on Cosmic-Ray Escape from Ultrahigh-energy Accelerators

Contact Info

Product

Resources

About

Floor of Cosmogenic Neutrino Fluxes above 10¹⁷ eV