Modelling the average spectrum expected from a population of gamma-ray globular clusters
Abstract
Millisecond pulsars occur abundantly in globular clusters. They are expected to be
responsible for several spectral components in the radio through γ-ray waveband (e.g., involving
synchrotron and inverse Compton emission), as have been seen by Radio Telescope Effelsberg,
Chandra X-ray Observatory, Fermi Large Area Telescope, and the High Energy Stereoscopic
System (H.E.S.S.) in the case of Terzan 5 (with fewer spectral components seen for other globular
clusters). H.E.S.S. has recently performed a stacking analysis involving 15 non-detected globular
clusters and obtained quite constraining average flux upper limits above 230 GeV. We present
a model that assumes millisecond pulsars as sources of relativistic particles and predicts multiwavelength emission from globular clusters. We apply this model to the population of clusters
mentioned above to predict the average spectrum and compare this to the H.E.S.S. upper limits.
Such comparison allows us to test whether the model is viable, leading to possible constraints
on various average cluster parameters within this framework
URI
http://hdl.handle.net/10394/32124http://events.saip.org.za/getFile.py/access?resId=68&materialId=6&confId=34