Dark matter distribution in X-ray luminous galaxy clusters with Emergent Gravity

TL;DR

This study tests the emergent gravity theory by analyzing the dark matter distribution in two galaxy clusters, finding discrepancies in the inner regions but agreement at larger radii, challenging traditional dark matter models.

Contribution

It provides observational constraints on emergent gravity predictions using X-ray and SZ data for galaxy clusters, highlighting differences from standard dark matter profiles.

Findings

Dark matter profile differs from traditional models in inner regions

Emergent gravity matches observed profiles beyond R_{500}

Discrepancies are larger in the cluster cores

Abstract

We present the radial distribution of the dark matter in two massive, X-ray luminous galaxy clusters, Abell~2142 and Abell~2319, and compare it with the quantity predicted as apparent manifestation of the baryonic mass in the context of the "Emergent Gravity" scenario, recently suggested from Verlinde (2016). Thanks to the observational strategy of the \xmm\ Cluster Outskirt Programme (X-COP), using the X-ray emission mapped with \xmm\ and the SZ signal in the Planck survey, we recover the gas density, temperature and thermal pressure profiles up to $\sim R_{200}$, allowing to constrain at unprecedented level the total mass through the hydrostatic equilibrium equation. We show that, also including systematic uncertainties related to the X-ray based mass modelling, the apparent "dark" matter shows a radial profile that has a shape different from the traditional dark matter distribution, with larger discrepancies (by a factor 2--3) in the inner ($r<200$ kpc) cluster's regions and a remarkable agreement only across $R_{500}$.