[Paper Review] Galaxy Interactions

Joshua E. Barnes|arXiv (Cornell University)|Nov 5, 1998

Astronomy and Astrophysical Research4 citations

TL;DR

This review examines galaxy interactions as a key laboratory for studying non-equilibrium stellar and gas dynamics, highlighting tidal forces, halo-mediated orbit decay, dissipative processes, merger remnants, and starburst origins. It synthesizes insights from N-body and hydrodynamic simulations to explain how interactions drive galaxy evolution, with key results showing that interactions trigger starbursts and shape merger remnants through energy dissipation and dynamical friction.

ABSTRACT

Interacting galaxies are a natural arena for studies of non-equilibrium stellar dynamics, gas dynamics, and thermodynamics. Only galaxy formation itself is as deeply concerned with as many different aspects of dynamics, and the connection between interactions and the formation of galaxies is probably no coincidence. This review discusses tidal interactions, halos and orbit decay, dissipative effects in galaxy interactions, properties of merger remnants, and origins of starbursts.

Motivation & Objective

• To analyze galaxy interactions as a natural laboratory for non-equilibrium stellar and gas dynamics.
• To investigate the role of tidal forces and halo-mediated orbit decay in shaping galaxy evolution.
• To explore dissipative effects such as gas compression and energy loss during interactions.
• To characterize the structural and kinematic properties of merger remnants.
• To examine the origins of starbursts in interacting systems.

Proposed method

• Utilizes N-body simulations to model stellar dynamics during galaxy encounters.
• Incorporates hydrodynamic simulations to study gas behavior and energy dissipation in interacting systems.
• Analyzes tidal forces and orbital decay due to dynamical friction in dark matter halos.
• Examines the evolution of merger remnants through post-merger relaxation and structural changes.
• Models star formation triggered by gas compression and shock heating in interacting galaxies.
• Reviews observational and theoretical connections between interactions and starburst activity.

Experimental results

Research questions

• RQ1 How do tidal interactions influence the structural evolution of galaxies?
• RQ2 What role does dynamical friction in dark matter halos play in orbital decay during galaxy encounters?
• RQ3 How do dissipative processes such as gas compression and shock heating contribute to star formation in interacting systems?
• RQ4 What are the characteristic morphological and kinematic properties of merger remnants?
• RQ5 What physical mechanisms trigger starbursts in interacting galaxies?

Key findings

• Tidal interactions significantly alter galaxy morphology and drive mass redistribution through strong gravitational torques.
• Dynamical friction in dark matter halos accelerates orbital decay, leading to rapid coalescence of interacting galaxies.
• Gas dissipation through shocks and compression leads to enhanced star formation, explaining the origin of starbursts in interacting systems.
• Merger remnants exhibit relaxed, spheroidal morphologies with increased central surface brightness and velocity dispersion.
• Simulations show that starburst activity is most intense during the final coalescence phase, peaking when gas is maximally compressed.
• The connection between galaxy interactions and starburst activity is robustly supported by both theoretical modeling and observational data.