We revise the astrophysical bound to the axion-photon coupling, as obtained by comparing R = NHB/NRGB, the ratio of the numbers of stars observed in the Horizontal Branch (HB) and in the Red Giant Branch (RGB) of 39 Galactic Globular Clusters with up-to-date theoretical predictions. First results have already been published in a PRL paper in 2014. Here we present a new and more accurate method to calculate the theoretical R, which makes use of synthetic Color-Magnitude diagrams to be directly compared to the observed (real) diagrams. Preliminary results of our analysis are discussed.
Axion-Photon Coupling: Astrophysical Constraints
Alessandro Mirizzi;
2015-01-01
Abstract
We revise the astrophysical bound to the axion-photon coupling, as obtained by comparing R = NHB/NRGB, the ratio of the numbers of stars observed in the Horizontal Branch (HB) and in the Red Giant Branch (RGB) of 39 Galactic Globular Clusters with up-to-date theoretical predictions. First results have already been published in a PRL paper in 2014. Here we present a new and more accurate method to calculate the theoretical R, which makes use of synthetic Color-Magnitude diagrams to be directly compared to the observed (real) diagrams. Preliminary results of our analysis are discussed.File in questo prodotto:
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