Exploring the Galactic Plane: A Comparative Study of Fermi-LAT Sources and HESS's Non-Detection at TeV Energies

TL;DR

This paper compares Fermi-LAT high-energy gamma-ray sources with HESS VHE upper-limits in the Galactic plane, identifying sources that challenge current models and guiding future observations.

Contribution

It provides a systematic comparison between Fermi-LAT spectra and HESS upper-limits, highlighting sources with unexpected flux predictions for future VHE studies.

Findings

Some Fermi-LAT sources exceed HESS upper-limits when extrapolated.

Identification of sources with potential for future VHE detection.

Insights into gamma-ray emission mechanisms in the Galactic plane.

Abstract

The HESS Galactic Plane Survey (HGPS), published in 2018, presented a decade of very-high-energy (VHE) gamma-ray observations along the Galactic plane. This study was accompanied by the release of several maps in FITS format, offering a detailed view of the region. The flux upper-limits from these HGPS maps can be compared to the high-energy (HE) spectra of sources catalogued by the Fermi-LAT in the same region. For some sources, extrapolating the Fermi-LAT flux into the VHE range predicts flux values exceeding the upper-limits set by HESS. In this work, we present the results of this comparison and highlight the sources that are of particular interest for future VHE observations.