K-mouflage effects on clusters of galaxies

Abstract

We investigate the effects of a K-mouflage modification of gravity on the dynamics of clusters of galaxies. We extend the description of K-mouflage to situations where the scalar field responsible for the modification of gravity is coupled to a perfect fluid with pressure. We describe the coupled system at both the background cosmology and cosmological perturbations levels, focusing on cases where the pressure emanates from small-scale nonlinear physics. We derive these properties in both the Einstein and Jordan frames, as these two frames already differ by a few percents at the background level for K-mouflage scenarios, and next compute cluster properties in the Jordan frame that is better suited to these observations. Galaxy clusters are not screened by the K-mouflage mechanism and therefore feel the modification of gravity in a maximal way. This implies that the halo mass function deviates from $\Lambda$-CDM by a factor of order one for masses $M\gtrsim 10^{14}{h}^{-1}{M}_{\odot }$. We then consider the hydrostatic equilibrium of gases embedded in galaxy clusters and the consequences of K-mouflage on the X-ray cluster luminosity, the gas temperature, and the Sunyaev-Zel'dovich effect. We find that the cluster temperature function, and more generally number counts, are largely affected by K-mouflage, mainly due to the increased cluster abundance in these models. Other scaling relations such as the mass-temperature and the temperature-luminosity relations are only modified at the percent level due to the constraints on K-mouflage from local Solar System tests.

34 pages

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Cited by in corpus (19)

• The Novel Probes Project -- Tests of Gravity on Astrophysical Scales
• Testing Screened Modified Gravity
• Testing Gravity Using Galaxy Clusters: New Constraints on Beyond Horndeski Theories
• Cosmological Constraints on sub-horizon scales modified gravity theories with MGCLASS II
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• Distinguishing modified gravity models
• 3D Weak Lensing: Modified Theories of Gravity
• Euclid: Constraining linearly scale-independent modifications of gravity with the spectroscopic and photometric primary probes
• The effective field theory of K-mouflage
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• The cosmological analysis of X-ray cluster surveys; III. 4D X-ray observable diagrams
• Extended Chameleons
• Explaining JWST star formation history at $z\sim 17$ by modifying $\Lambda$CDM
• Extended Gravity Constraints at Different Scales
• K-mouflage at high $k$: extending the reach of $\text{Hi-COLA}$
• Non-screening of the Cosmological Background in K-mouflage modified gravity
• Lyman-alpha power spectrum as a probe of modified gravity