A Possible Hadronic Explanation for the Ultra-high-energy γ-Ray Emission from 1LHAASO J0056+6346u
- 1Yunnan University
Abstract
The release of the first LHAASO catalog has marked a new era of γ -ray astronomy and promoted the search for Galactic PeVatrons. Among the currently reported ultra-high-energy (UHE; ≳100 TeV) sources, 1LHAASO J0056+6346u is a peculiar unidentified object lacking a firm association with any known accelerator despite its spatial coincidence with adjacent molecular clouds (MCs). In this work, we propose a scenario where the accelerated protons escaping from a putative supernova remnant (SNR) penetrate nearby MCs and produce the observed UHE γ -rays through inelastic pp collisions. By utilizing the Markov Chain Monte Carlo routines, we fit the γ -ray observational data and constrain key physical parameters of the system. Our fits favor a young system with a short Sedov time, characterized by an SNR age of t SNR ≃ 1.4–2.2 kyr, an SNR–cloud separation d ≃ 22–35 pc, a characteristic proton cutoff energy E c ≃ 0.4–0.5 PeV, and a cosmic-ray (CR) conversion fraction f CR ≃ 0.10–0.16. These results suggest that 1LHAASO J0056+6346u may trace a young SNR illuminating nearby molecular gas with an early escape of the accelerated protons. In addition, we calculate the accompanying neutrino fluxes and find that they are well below the sensitivities of current neutrino observatories and remain beneath the atmospheric neutrino background.
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BibTeX
@article{he2026possible,
title = {{A Possible Hadronic Explanation for the Ultra-high-energy γ-Ray Emission from 1LHAASO J0056+6346u}},
author = {Chunhui He and Can Zhang and Shan Chang and Biwen Bao and Li Zhang},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/aeaa2f},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeaa2f},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A Possible Hadronic Explanation for the Ultra-high-energy γ-Ray Emission from 1LHAASO J0056+6346u
AU - Chunhui He
AU - Can Zhang
AU - Shan Chang
AU - Biwen Bao
AU - Li Zhang
PY - 2026
DA - 2026/10/28
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aeaa2f
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aeaa2f
AB - The release of the first LHAASO catalog has marked a new era of γ -ray astronomy and promoted the search for Galactic PeVatrons. Among the currently reported ultra-high-energy (UHE; ≳100 TeV) sources, 1LHAASO J0056+6346u is a peculiar unidentified object lacking a firm association with any known accelerator despite its spatial coincidence with adjacent molecular clouds (MCs). In this work, we propose a scenario where the accelerated protons escaping from a putative supernova remnant (SNR) penetrate nearby MCs and produce the observed UHE γ -rays through inelastic pp collisions. By utilizing the Markov Chain Monte Carlo routines, we fit the γ -ray observational data and constrain key physical parameters of the system. Our fits favor a young system with a short Sedov time, characterized by an SNR age of t SNR ≃ 1.4–2.2 kyr, an SNR–cloud separation d ≃ 22–35 pc, a characteristic proton cutoff energy E c ≃ 0.4–0.5 PeV, and a cosmic-ray (CR) conversion fraction f CR ≃ 0.10–0.16. These results suggest that 1LHAASO J0056+6346u may trace a young SNR illuminating nearby molecular gas with an early escape of the accelerated protons. In addition, we calculate the accompanying neutrino fluxes and find that they are well below the sensitivities of current neutrino observatories and remain beneath the atmospheric neutrino background.
SN - 1538-4357
SN - 0004-637X
ER -