LHAASO protons versus LHAASO diffuse gamma-rays: a consistency check

TL;DR

This study compares LHAASO's proton spectrum measurements with gamma-ray observations, revealing a significant mismatch that questions existing cosmic-ray models and suggests the need for their revision.

Contribution

It provides the first direct consistency check between LHAASO's proton spectrum and diffuse gamma-ray emission, highlighting discrepancies in normalization and spectral shape.

Findings

Predicted gamma-ray flux exceeds LHAASO data in all Galactic regions.

The mismatch challenges conventional cosmic-ray and gamma-ray emission models.

Current models may need revision to accurately describe TeV-PeV cosmic-ray phenomena.

Abstract

We perform the first direct consistency check between the recently measured proton spectrum at the knee by Large High Altitude Air Shower Observatory (LHAASO) and the collaboration's own high-precision mapping of Galactic diffuse gamma-ray emission. By modeling the hadronic gamma-ray production using the updated cosmic-ray spectra, gas templates and cross-section models, we show that the predicted gamma-ray flux robustly overshoots the LHAASO data in both inner and lateral Galactic regions. This persistent mismatch in both normalization and spectral shape challenges conventional scenarios linking the local cosmic-ray sea to Galactic gamma-ray emission, and calls for a revision of current cosmic ray models in the TeV-PeV sky.