Galactic Gamma-Ray Diffuse Emission at TeV energies with HAWC Data

TL;DR

This paper analyzes TeV gamma-ray diffuse emission from the Galactic Plane using HAWC data, revealing higher flux than models predict and suggesting unresolved sources or CR flux variations as possible explanations.

Contribution

It presents the first detailed spectral and spatial analysis of TeV diffuse emission in a specific Galactic region with HAWC data, highlighting discrepancies with existing models.

Findings

Measured flux is about twice the exttt{DRAGON} model prediction.

Spectral distribution aligns with cosmic ray spectra.

Unresolved sources and CR flux variations may explain flux excess.

Abstract

The Galactic gamma-ray diffuse emission (GDE) is emitted by cosmic rays (CRs), ultra-relativistic protons and electrons, interacting with gas and electromagnetic radiation fields in the interstellar medium. Here we present the analysis of TeV diffuse emission from a region of the Galactic Plane over the range in longitude of $l\in[43^\circ,73^\circ]$, using data collected with the High Altitude Water Cherenkov (HAWC) detector. Spectral, longitudinal and latitudinal distributions of the TeV diffuse emission are shown. The radiation spectrum is compatible with the spectrum of the emission arising from a CR population with an "index" similar to that of the observed CRs. When comparing with the \texttt{DRAGON} \textit{base model}, the HAWC GDE flux is higher by about a factor of two. Unresolved sources such as pulsar wind nebulae and TeV halos could explain the excess emission. Finally, deviations of the Galactic CR flux from the locally measured CR flux may additionally explain the difference between the predicted and measured diffuse fluxes.