Are GeV and TeV spectra connected? the case of Galactic gamma-ray sources

Abstract

To understand Galactic objects that emits GeV-TeV emission, a spatial correlation study between the Fermi bright source catalog and TeV source population was carried out in Tam et al. (2010), finding that a significant number of very high-energy (VHE; E >100 GeV) sources are also emitting at GeV energies. We extended our previous study utilizing the first Fermi catalog (1FGL) sources. A cross-correlation comparison of the 1FGL sources was carried out with the VHE gamma-ray sources in the literature as of May 2011. While it is found that a significant number of VHE gamma-ray sources were also detected in the GeV band, the GeV-TeV spectra of some of these spatially coincident sources cannot be described by a single spectral component. While some of these cases are gamma-ray pulsars accompanied by VHE gamma-ray emitting nebulae, we present cases where the 100 MeV to multi-TeV spectra of coincident 1FGL/VHE source pairs do not seem to be well fit by a single spectral component.