Cluster number counts in dark energy model with energy and momentum coupling to dark matter

TL;DR

This paper investigates how momentum and energy coupling between dark energy and dark matter affect galaxy cluster counts, finding that such couplings can increase counts at higher redshifts but do not significantly improve fit over the standard model.

Contribution

It introduces a model of dark energy-dark matter coupling with momentum transfer and analyzes its impact on cluster number counts compared to $ ext{Lambda}$CDM.

Findings

Cluster counts are enhanced at higher redshifts with increased momentum transfer.

The model's predicted counts are larger than eROSITA observations but not statistically significant.

No significant improvement over $ ext{Lambda}$CDM}.

Abstract

The influences on the cluster number counts from the coupling between dark energy and dark matter with momentum transfer are investigated. We find that the extrapolated linear density contrast computed from the spherical collapse model is suppressed when the strength of momentum transfer is increased. Using the Sheth-Tormen mass function, the cluster number counts are computed. The minimum mass limit in the mass integration for each redshift bin is determined by matching the predicted number counts from the $\Lambda$CDM model with the result from eROSITA surveys. We find that the number of clusters is maximal at a higher redshift bin, and the number of clusters in a maximum redshift bin is enhanced when the strength of momentum and energy transfers increases due to the reduction of extrapolated linear density contrast. Setting the parameters of the dark energy model with momentum coupling according to the observational constraints in \cite{bestfit}, the predicted number counts from the coupled dark energy is larger than the result from eROSITA surveys. The statistical analysis yields a $p$-value of 0.189 for the proposed model relative to $\Lambda$CDM. Consequently, there is no statistically significant evidence of an improved fit over the standard $\Lambda$CDM framework based on the eROSITA cluster number counts.