Garrel, Christian ; Pierre, Marguerite ; Valageas, Patrick ; Eckert, Dominique search by orcid ; Marulli, Federico ; Veropalumbo, Alfonso ; Pacaud, Florian ; Clerc, Nicolas ; Sereno, Mauro ; Umetsu, Keiichi ; Moscardini, Lauro ; Bhargava, Sunayana ; Adami, Christophe ; Chiappetti, Lucio search by orcid ; Gastaldello, Fabio ; Koulouridis, Elias ; Le Fevre, Jean-Paul ; Plionis, Manolis
eprint arXiv:2109.13171
Publication year: 2021

We present the forward cosmological analysis of an XMMXMM selected sample of galaxy clusters out to a redshift of unity. Following our previous 2018 study based on the dn/dz quantity alone, we perform an upgraded cosmological analysis of the same XXL C1 cluster catalogue (178 objects), with a detailed account of the systematic errors. We follow the ASpiX methodology: the distribution of the observed X-ray properties of the cluster population is analysed in a 3D observable space (count rate, hardness ratio, redshift) and modelled as a function of cosmology. Compared to more traditional methods, ASpiX allows the inclusion of clusters down to a few tens of photons. We obtain an improvement by a factor of 2 compared to the previous analysis by letting the normalisation of the M-T relation and the evolution of the L-T relation free. Adding constraints from the XXL cluster 2-point correlation function and the BAO from various surveys decreases the uncertainties by 23 and 53 % respectively, and 62% when adding both. Switching to the scaling relations from the Subaru analysis, and letting free more parameters, our final constraints are σ8σ8 = 0.99+0.140.230.99−0.23+0.14ΩmΩm = 0.296 ±± 0.034 (S8=0.98+0.110.21S8=0.98−0.21+0.11) for the XXL sample alone. Finally, we combine XXL ASpiX, the XXL cluster 2-point correlation function and the BAO, with 11 free parameters, allowing for the cosmological dependence of the scaling relations in the fit. We find σ8σ8 = 0.793+0.0630.120.793−0.12+0.063ΩmΩm = 0.364 ±± 0.015 (S8=0.872+0.0680.12S8=0.872−0.12+0.068), but still compatible with Planck CMB at 2.2σσ. The results obtained by the ASpiX method are promising; further improvement is expected from the final XXL cosmological analysis involving a cluster sample twice as large. Such a study paves the way for the analysis of the eROSITA and future Athena surveys.

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