Substructures formation induced by gravitational tides?

TL;DR

This paper explores how compressive gravitational tides during galaxy mergers influence the formation and properties of star clusters, revealing a strong correlation between tidal modes and observed cluster distributions.

Contribution

It introduces the concept of compressive tides and demonstrates their significance in galaxy mergers, particularly in the Antennae galaxies, linking gravitational effects to star cluster formation.

Findings

Compressive tides occur during galaxy mergers and impact substructure dynamics.

The positions and timescales of compressive tides match young cluster distributions.

A correlation exists between gravitational tides and star cluster properties.

Abstract

Physics lectures always refer to the tides as a disruptive effect. However, tides can also be compressive. When the potential of two galaxies overlap, as happens during a merger, fully compressive tides can develop and have a strong impact on the dynamics of substructures such as star clusters or tidal dwarf galaxies. Using N-body simulations of a large set of mergers, we noticed the importance of these tidal modes at cluster scale. With a model of the Antennae galaxies, we conclude that the positions and timescales of these tidal modes match the actual distribution of young clusters. A detailed study of the statistics of the compressive tides shows a stunning correlation between this purely gravitational effect and the observed properties of the star clusters. In this contribution, we introduce the concept of compressive tide and show its relevance in the special case of the Antennae galaxies. We extend our conclusions to a broad range of parameters and discuss their implications on several critical points such as the infant mortality, multiple star formation epochs in clusters or the age distribution.