Geminga SNR: Possible candidate of local cosmic-ray factory

TL;DR

This paper investigates local cosmic-ray sources, using spectral and anisotropy data, and identifies Geminga SNR as the most probable candidate among known nearby supernova remnants.

Contribution

It introduces a Bayesian inference-based method to constrain local source parameters and identifies Geminga SNR as the likely origin of local cosmic rays.

Findings

Geminga SNR is the most probable local cosmic-ray source.

Parameter space for source location and age is significantly constrained.

Spectral and anisotropy data together effectively identify local sources.

Abstract

The precise measurements of energy spectra and anisotropy could help us uncover the local cosmic-ray accelerators. Our recent works have shown that spectral hardening above $200$ GeV in the energy spectra and transition of large-scale anisotropy at $\sim 100$ TeV are of local source origin. Less than $100$ TeV, both spectral hardening and anisotropy explicitly indicate the dominant contribution from nearby sources. In this work, we further investigate the parameter space of sources allowed by the observational energy spectra and anisotropy amplitude. To obtain the best-fit source parameters, a numerical package to compute the parameter posterior distributions based on Bayesian inference, which is applied to perform an elaborate scan of parameter space. We find that by combining the energy spectra and anisotropy data, the permissible range of location and age of local source is considerably reduced. When comparing with the current local SNR catalog, only Geminga SNR could be the proper candidate of the local cosmic-ray source.