Modelling uncertainties in GeV - TeV flux predictions of Galactic globular clusters

Discussion timeslot (ZOOM-Meeting): 16. July 2021 - 12:00
ZOOM-Meeting URL: https://desy.zoom.us/j/98542982538
ZOOM-Meeting ID: 98542982538
ZOOM-Meeting Passcode: ICRC2021
Corresponding Session: https://icrc2021-venue.desy.de/channel/50-Galactic-Compact-Objects-Pulsars-Binary-Systems-Microquasars-GAD-GAI/124
Live-Stream URL: https://icrc2021-venue.desy.de/livestream/Discussion-04/5

Abstract:
'Globular clusters are multi-band emitters, with their gamma-ray emission having been variously attributed as due to dark matter annihilation, a resident gamma-ray burst, white-dwarf population, or a millisecond-pulsar population hosted by the cluster. Terzan 5 has plausibly been detected in the gamma-ray band by H.E.S.S., which produced constraining stacking upper limits on the integral gamma-ray flux of a population of other globular clusters. Using a leptonic model that invokes host millisecond pulsars in globular clusters as sources of relativistic particles, we demonstrate that uncertainty in model parameters leads to a large spread in the predicted high-energy flux, yet there are regions in parameter space for which the stringent H.E.S.S. stacking upper limits are satisfied. Two additional case studies on M15 and Omega Cen (from which five pulsars have recently been detected at radio frequencies) indicate that it is important to increase measurement accuracy on key model parameters in order to improve precision in predictions of cluster fluxes. This has important implications for the observational strategy of the Cherenkov Telescope Array.'

Authors: Christo Venter
Co-Authors: Hambeleleni Ndiyavala-Davids | Andreas Kopp | Michael Backes
Indico-ID: 1176
Proceeding URL: https://pos.sissa.it/395/927