Merging of spiral galaxies: observations and modeling

TL;DR

This paper models the complex dynamics of merging spiral galaxies, including gas, stars, and dark matter, using advanced numerical simulations to match observed galaxy morphologies and kinematics.

Contribution

It introduces a comprehensive multi-component simulation approach with gas heating/cooling and direct gravitational calculations, improving the understanding of galaxy merger processes.

Findings

Successful modeling of gas bridges in merging galaxies

Reconciliation of models with observed galaxy structures

Insights into gas dynamics during galaxy collisions

Abstract

We present a study of the dynamics of multi-component models of spiral galaxies at various stages of grand merging. Numerical models include a self-consistent account of the dynamics of collisionless stellar subsystems and N-body dark matter, as well as gaseous components. Calculation of gas heating and cooling processes allows us to consider a wide temperature range from 80 to 100 thousand degrees. Using the Smoothed-particle hydrodynamics method to solve hydrodynamic equations makes it possible to track the evolution of the gas of each galaxy, calculating the content of gas components of each object in the process of complex interchange of matter. The gravitational interaction is determined in a direct way by summing the contributions according to Newton's law, which minimizes the modeling error. This requires significant computing resources using graphics accelerators on hybrid computing platform CPU + multi-GPUs. The study aims to reconcile theoretical models with the morphology and kinematics of a number of observed systems. In particular, Taffy-type objects are considered, where two galaxies are connected by a gas bridge with a characteristic small-scale gas structure after the disks pass through each other in an approximately flat orientation. Examples of such systems are the observed pairs of galaxies UGC 12914/UGC 12915, NGC 4490/NGC 4485, UGC813/UGC816 etc.