Helium abundance (and $H_0$) in X-COP galaxy clusters

S. Ettori; V. Ghirardini; D. Eckert

doi:10.1002/asna.202023780

paper

Helium abundance (and $H_{0}$ ) in X-COP galaxy clusters

arXiv:1911.05039 · doi:10.1002/asna.202023780

Abstract

We present the constraints on the helium abundance in 12 X-ray luminous galaxy clusters that have been mapped in their X-ray and Sunyaev-Zeldovich (SZ) signals out to $R_{200}$ for the XMM-Newton Cluster Outskirts Project (X-COP). The unprecedented precision available for the estimate of $H_{0}$ allows us to investigate how much the reconstructed X-ray and SZ signals are consistent with the expected ratio $x$ between helium and proton densities of 0.08-0.1. We find that a $H_{0}$ around 70 km/s/Mpc is preferred from our measurements, with lower values of $H_{0}$ as requested from the Planck collaboration (67 km/s/Mpc) requiring a 34% higher value of $x$ . On the other hand, higher values of $H_{0}$ , as obtained by measurements in the local universe, impose $x$ , from the primordial nucleosynthesis calculations and current solar abundances, reduced by 37--44\%.

arXiv comment7 pages. To appear as proceedings article for the XMM-Newton Workshop "Astrophysics of Hot Plasma in Extended X-ray Sources" held at European Space Astronomy Centre, Madrid, Spain, on 12-14 June 2019

Helium abundance (and $H_{0}$ ) in X-COP galaxy clusters

Abstract

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Helium abundance (and H0​) in X-COP galaxy clusters

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Helium abundance (and $H_{0}$ ) in X-COP galaxy clusters