# How the Coherent Tides Obstruct the Radial Infalls of Satellite Galaxies onto Clusters

## TL;DR

This study provides numerical evidence that coherent tidal forces significantly hinder the radial infall of satellite galaxies onto clusters, especially in specific large-scale environments, revealing a new aspect of galaxy cluster formation.

## Contribution

It introduces the concept of tidal coherence as a factor obstructing satellite infall, supported by high-resolution N-body simulation data.

## Key findings

- Higher tidal coherence correlates with reduced radial velocities of satellites.
- Satellites closer to clusters and in anisotropic environments are more affected.
- Coherent tides impede the radial infall process of satellites.

## Abstract

A direct numerical evidence for the obstructing effect of the coherent tides on the infall-zone satellites around the cluster halos is presented. Analyzing the numerical data from a high-resolution N-body simulation, we calculate the mean fractions of the radial and tangential velocities of the infall-zone satellites around the cluster halos and investigate if and how they depend on the tidal coherence defined as the alignments between the major principal axes of the local tidal fields smoothed on the linear and nonlinear scales. It is found that the infall-zone satellites located in the regions with higher tidal coherence have significantly smaller and larger mean fractions of the radial and tangential velocities, respectively, which indicates that the radial infall of satellites onto host clusters are obstructed by the coherent tides. We also show that those satellites separated by shorter distances from the host clusters, having lower-masses, and embedded in the anisotropic large-scale environments like filaments and sheets, are more vulnerable to the obstructing effect of the coherent tides.