Generalised scalar-tensor theories of gravity and pressure profiles of galaxy clusters

TL;DR

This paper tests degenerate higher-order scalar-tensor (DHOST) gravity theories against galaxy cluster data, finding that such theories can produce small-scale modifications to gravity and are viable alternatives to Lambda-CDM, with preliminary constraints derived from X-ray and SZ observations.

Contribution

It provides the first constraints on DHOST theories using galaxy cluster data, exploring their effects on gravitational potentials and pressure profiles.

Findings

DHOST theories can modify gravitational potentials in galaxy clusters.

Preliminary constraints on DHOST parameters from X-ray and SZ data.

Potential for future high-resolution observations to refine tests.

Abstract

In the current proceedings, we summarise the results presented during the mm Universe@NIKA2 conference, taken from our main results in \cite{Haridasu:2021hzq}. We test the Degenerate higher-order scalar-tensor(DHOST) theory as a generalised platform for scalar-tensor theory at galaxy cluster scales to predict in such static systems small scale modification to the gravitational potential. {DHOST theory is not only a good alternative to $\Lambda$CDM for the background evolution but also predicts small-scale modification to the gravitational potential in static systems such as galaxy clusters.} With a sample of 12 clusters with accurate X-ray Intra Cluster Medium (ICM) data (X-COP project) and Sunyaev-Zel'dovich (SZ) ICM pressure (Planck satellite), we place preliminary constraints on the DHOST parameters defining the deviation from GR. Moreover, we also collect a few supplementary analyses we have performed during the course: i) Gaussian process reconstruction without parametric assumptions, ii) $\Psz$-only data analysis not aided by the X-ray data. Finally, we present possible extensions to the current work which may benefit from future high sensitivity and spatial resolution observations such as the ongoing NIKA2 camera.