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arXiv · 2109.13171

The XXL survey: XLVI. Forward cosmological analysis of the C1 cluster sample

Christian Garrel·Marguerite Pierre·Patrick Valageas·Dominique Eckert·Federico Marulli·Alfonso Veropalumbo·Florian Pacaud·Nicolas Clerc·Mauro Sereno·Keiichi Umetsu·Lauro Moscardini·Sunayana Bhargava·Christophe Adami·Lucio Chiappetti·Fabio Gastaldello·Elias Koulouridis·Jean-Paul Le Fevre·Manolis Plionis
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Abstract

We present the forward cosmological analysis of an $XMM$ 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 $\sigma_8$ = $0.99^{+0.14}_{-0.23}$, $\Omega_m$ = 0.296 $\pm$ 0.034 ($S_8 = 0.98^{+0.11}_{-0.21}$) 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 $\sigma_8$ = $0.793^{+0.063}_{-0.12}$, $\Omega_m$ = 0.364 $\pm$ 0.015 ($S_8 = 0.872^{+0.068}_{-0.12}$), but still compatible with Planck CMB at 2.2$\sigma$. 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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Christian Garrel, Marguerite Pierre, Patrick Valageas, Dominique Eckert, Federico Marulli, Alfonso Veropalumbo, Florian Pacaud, Nicolas Clerc, Mauro Sereno, Keiichi Umetsu, Lauro Moscardini, Sunayana Bhargava, Christophe Adami, Lucio Chiappetti, Fabio Gastaldello, Elias Koulouridis, Jean-Paul Le Fevre, Manolis Plionis. 2021-09-27. The XXL survey: XLVI. Forward cosmological analysis of the C1 cluster sample. https://doi.org/10.1051/0004-6361%2F202141204

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