dc.contributor.author Venter, C. dc.contributor.author Kopp, A. dc.date.accessioned 2019-04-03T10:34:10Z dc.date.available 2019-04-03T10:34:10Z dc.date.issued 2015 dc.identifier.citation Venter, C. & Kopp, A. 2015. The expected very-high-energy flux from a population of globular clusters. High Energy Astrophysics in Southern Africa 2014: a multi-frequency perspective of new frontiers in High Energy Astrophysics in Southern Africa Boyden Observatory, April 24-25, 2014. Memorie della Societa Astronomica Italiana, 86:70-77. [http://sait.oat.ts.astro.it/MmSAI/86/PDF/70.pdf] en_US dc.identifier.issn 0037-8720 dc.identifier.uri http://hdl.handle.net/10394/32121 dc.identifier.uri http://sait.oat.ts.astro.it/MmSAI/86/PDF/70.pdf dc.description.abstract Given their old ages, globular clusters are expected to harbour many evolved en_US stellar objects. Their high core densities enhance stellar encounter rates, also facilitating the formation of stellar end products. In particular, many millisecond pulsars are found in these clusters. Such a population of millisecond pulsars is expected to radiate several spectral components in the radio through γ-ray waveband. We present ongoing work involving a refined spectral model that assumes millisecond pulsars as sources of relativistic particles to model the multi-wavelength emission properties of globular clusters. We apply the model to a population of globular clusters that have been observed by H.E.S.S. and use upper limits derived from stacking analyses to test the viability of this “millisecond pulsar scenario”. We derive general expressions for the ensemble-averaged flux and its error stemming from the uncertainty in free model parameters. The errors exceed this calculated average flux value so that there are regions in parameter space for which the model predictions satisfy the H.E.S.S. upper limits. Improved constraints on single-cluster parameters are therefore needed to aid in discriminating between competing spectral models dc.language.iso en en_US dc.publisher SAIt en_US dc.subject Galaxy: globular clusters en_US dc.subject Gamma rays: general en_US dc.subject Radiation mechanisms: non-thermal en_US dc.title The expected very-high-energy flux from a population of globular clusters en_US dc.type Article en_US dc.contributor.researchID 24483818 - Kopp, Andreas dc.contributor.researchID 12006653 - Venter, Christo
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