Detall

Seminar

Galactic Sources of VHE Gamma-Ray Emission: Highlights from VERITAS

By: Reshmi Mukherjee - Barnard College, Columbia University

Date: Monday, 25 November, 2024 at 15:00

Place: Pere Pascual V5.07 Room and via Zoom

Abstract: The VERITAS (Very Energetic Radiation Imaging Telescope Array System) observatory, located in southern Arizona, has a robust program in exploring the sources of very high-energy (VHE) gamma-ray emission in our Galaxy. With its array of four atmospheric Cherenkov telescopes, VERITAS observes gamma rays at energies above 100 GeV, providing critical insights into a variety of galactic sources, including shell-type supernova remnants (SNRs), pulsar wind nebulae (PWNe), gamma-ray binary systems, and PeVatrons—astrophysical accelerators that may account for the bulk of the cosmic-ray flux up to the knee. Recent observations of PWNe and SNRs by VERITAS have been instrumental in expanding our understanding of these objects, which dominate the population of known galactic TeV gamma-ray emitters. These studies are vital for probing the energetic particle populations (leptons, hadrons, or a mix) responsible for their gamma-ray emission.

VERITAS's contribution is especially important for identifying candidate PeVatrons, sources capable of accelerating particles to several PeV (~10^15 eV) and likely responsible for the highest energy cosmic rays. In particular, the discovery of sources emitting above 100 TeV by instruments like HAWC and LHAASO, which often lack counterparts at lower energy bands, has spurred new investigations. VERITAS's high-resolution VHE observations, combined with broadband modeling efforts, provide a clearer picture of the emission mechanisms in these sources, especially in cases where associations with known counterparts, such as molecular clouds or compact objects, are ambiguous.

This presentation will summarize VERITAS's recent results on galactic PeVatron candidates, emphasizing the role of SNRs, PWNe, and other high-energy sources in contributing to the cosmic-ray spectrum. We will also explore ongoing collaborations, including remote participation by the VHE Astrophysics Group at Columbia University, and discuss potential future studies with the local ICCUB group. These efforts aim to deepen our understanding of the nature and emission processes of these fascinating astrophysical accelerators.