Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2504.10847

Cosmic-Ray Constraints on the Flux of Ultra-High-Energy Neutrino Event KM3-230213A

Saikat Das·Bing Zhang·Soebur Razzaque·Siyao Xu
View original source ↗Read source document ↗Export metadata ↓

Abstract

The detection of a $\simeq220$~PeV muon neutrino event by the KM3NeT telescope offers an unprecedented opportunity to probe the Universe at extreme energies. A photopion interaction origin of the neutrino requires a parent cosmic-ray energy of $\gtrsim4$~EeV per nucleon. We analyze the origin of this event under three scenarios, i.e., a transient point source, diffuse astrophysical emission, and a line-of-sight interaction of an ultrahigh-energy cosmic-ray (UHECR; $E\gtrsim 0.1$~EeV). Our analysis includes the flux from both a KM3NeT-only fit and a joint fit, incorporating data from KM3NeT, IceCube, and the Pierre Auger Observatory. If the neutrino event originates from transients, it requires a new population of transients that is energetic, $γ$-ray dark, and more abundant than the known ones. In the framework of diffuse astrophysical emission, we compare the required local UHECR energy injection rate at $\gtrsim4$ EeV with the rate derived from the flux measurements by Auger, across various source redshift evolution models. This disfavors the KM3NeT-only fit considering the source evolution up to high values of redshift, while the joint fit remains viable for sources contributing up to a maximum redshift $z_{\rm max} \gtrsim 1$ for the limiting case of photopion interaction efficiency, $f_{pγ} = 0.1$. For a cosmogenic origin from point sources, the luminosity obtained at redshifts $z \lesssim 1$ from the joint fit is compatible with the Eddington luminosity of $\sim10^9 M_\odot$ black holes in active galactic nuclei, assuming a proton composition and optimistic values of extragalactic magnetic field strength.

Explore related subjects

astro-ph.HE

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Saikat Das, Bing Zhang, Soebur Razzaque, Siyao Xu. 2025-08-06. Cosmic-Ray Constraints on the Flux of Ultra-High-Energy Neutrino Event KM3-230213A. https://doi.org/10.3847/1538-4357%2Fadf8de

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Deciphering the Physical Origin of GRB 240825A: A Long GRB Lacking a Bright Supernova

We present a comprehensive multiwavelength analysis of GRB 240825A, a bright gamma-ray burst (GRB) detected by Fermi and Swift, with a prompt duration ($T_{\rm 90}$ $\sim$ 4 sec in 50-300 keV in GBM) near the boundary separating short and long GRBs, prompting a detailed investigation into its classification and progenitor. We use classical prompt metrics (duration, minimum variability timescale (MVT), lag, and spectral hardness) and modern classification techniques (machine-learning (ML) based t-SNE, support vector machine, energy-hardness-duration, and $\varepsilon \equiv E_{γ,\mathrm{iso},52} / E_{p,z,2}^{5/3}$) and find most properties (prompt energetics, placement on the Amati relation, and spectral lag) of GRB 240825A consistent with a collapsar origin. However, extensive late-time optical and NIR follow-up with the 10.4m GTC and 8.4m binocular LBT telescopes reveals no bright supernova (like SN 1998bw) is detected down to stringent limits (e.g., $m_r > 25.0$ mag at 17.59 days), despite a redshift of $z = 0.659$ measured from GTC spectroscopy. Host galaxy SED modeling with Prospector indicates a massive, and star-forming galaxy-typical of collapsar GRB hosts, though with a large offset. We compare these findings with hybrid events like GRB 211211A, GRB 230307A, GRB 200826A, including SNe-GRBs, and conclude that GRB 240825A most likely originated from a massive star collapse, possibly with the associated SN heavily obscured or intrinsically faint. This study emphasizes the need for multiwavelength follow-up and a multi-layered classification to determine GRB progenitors.

astro-ph.HE↗
arXiv2026

The impact of flickering variability and magnetisation on the dynamics, stability and morphology of radio-loud AGN jets

The physics governing the morphology of radio-loud AGN jets is not fully understood. We investigate how magnetization, flickering jet power and their interplay affects the morphology of radio galaxies. We present a grid of relativistic magnetohydrodynamic simulations using the PLUTO code covering constant and variable jets with two levels of magnetisation. We find that the constant high magnetisation jets can lead to highly asymmetrical cocoon morphologies, whilst the variable high magnetisation jet can exhibit a broken morphology, caused by a discontinuous jet beam. Our work highlights the importance of magnetisation and variability on the stability and resulting morphology of radio-loud AGN jets, suggesting both are significant factors in addition to jet power or environment. Furthermore, we show that the interaction between magnetisation and variability can lead to the development of localised kink instabilities along the jet beam. Finally, we discuss the effects of hydrodynamic mixing in low magnetisation jets and the role of viewing angle dependence in comparisons between our simulations and observed sources. To facilitate this comparison we present a library of simulated radio images at different times in the simulations and from various viewing angles, which highlight a diverse set of complex morphologies.

astro-ph.HE↗
arXiv2026

Magnetic Eruption and Nucleosynthesis in GRνMHD Simulations of Spinning Neutron Star Mergers

We present three-dimensional general relativistic magnetohydrodynamics simulations of equal-mass binary neutron star mergers with varied neutron star spin configurations and second-moment neutrino transport, following the formation and early evolution of long-lived remnants. We compare a fiducial irrotational binary with binaries having spins that are aligned or antialigned with the orbital angular momentum, and examime how spin affects the merger dynamics, magnetic field evolution, outflows, and nucleosynthesis. Compared to the fiducial case, the aligned spin configuration releases more cold, neutron-rich tidal ejecta in the equatorial plane, which enables the development of a more tightly collimated polar outflow erupting from the remnant and inner accretion disk. Conversely, the case with spins antialigned with the orbit experiences a more violent collision at merger, disrupting magnetic amplification, loading the environment with debris, and impeding the propagation of magnetically driven winds. Strong neutrino reprocessing of the polar outflow in the irrotational and aligned spin cases produces $2.4\times 10^{-3}\,M_\odot$ of proton-rich ($Y_e \geq 0.49$) material, resulting in the synthesis of light r-process elements, whose subsequent decay potentially sends a unique electromagnetic signal from long-lived remnants. However, the outflows remain too dense and slow to be consistent with typical short gamma-ray bursts.

astro-ph.HE↗