An SPH code for galaxy formation problems; Presentation of the code

TL;DR

This paper introduces a new adaptive SPH code for galaxy formation simulations that efficiently manages computational resources by merging particles in dense regions, improving simulation speed and resolution handling.

Contribution

The paper presents a novel SPH code with adaptive merging of particles in dense regions, optimizing computational efficiency for galaxy formation simulations.

Findings

The code effectively merges particles in dense regions, reducing computational load.

Simulations demonstrate improved speed without sacrificing resolution.

The method handles collision-less and collisional fluids in galaxy formation models.

Abstract

We present and test a code for two-fluid simulations of galaxy formation, one of the fluids being collision-less. The hydrodynamical evolution is solved through the SPH method while gravitational forces are calculated using a tree method. The code is Lagrangian, and fully adaptive both in space and time. A significant fraction gas in simulations of hierarchical galaxy formation ends up in tight clumps where it is, in terms of computational effort, very expensive to integrate the SPH equations. Furthermore, this is a computational waste since these tight gas clumps are typically not gravitationally resolved. We solve this by merging gas particles in these regions, thereby limiting the SPH resolution to the gravitational force resolution, and further speeding up the simulation through the reduction in the number of particles.