11:00 am–12:00 pm ERC 545
Host: Benedikt Schroer
Vittoria Vecchiotti (NTNU) "The high-energy Galactic gamma-ray emission: the diffuse component and the role of unresolved pulsar wind nebulae"
The study of the Galactic gamma-ray and neutrino diffuse emission represents an indirect way to investigate cosmic-ray propagation in the Galaxy. However, the signal produced by unresolved sources contaminates diffuse emission measurements, making their interpretation challenging. In order to quantify the relevance of the unresolved source component, we performed a population study of the H.E.S.S. Galactic Plane Survey under the assumption of sources powered by pulsar activity. We estimate the total TeV flux produced by all the sources in our Galaxy. In particular, our results show that a non-negligible fraction of this flux is produced by faint sources below the H.E.S.S. detection threshold. In the GeV energy range, a significant fraction of the TeV source population cannot be resolved by Fermi-LAT providing a relevant contribution to the large-scale diffuse emission, ranging within $\sim 4\%-40\%$ of the total diffuse $\gamma$-ray emission in the inner Galaxy. Hence, this unresolved component may account for a large part of the spectral index variation observed by Fermi-LAT as a function of the Galactocentric distance. Lastly, we calculate the hadronic diffuse emission in the sub-PeV energy range under different model assumptions and compare it to the large-scale diffuse emission observed by Tibet AS$\gamma$. We show that a pure hadronic emission underpredicts the measurements requiring the presence of an unresolved source component.
