# Cosmological Simulations of Satellites around Isolated Dwarf Galaxies

## TL;DR

This study uses high-resolution cosmological hydrodynamic simulations to explore the formation, evolution, and disruption of satellite dwarf galaxies, revealing key factors influencing their survival and properties.

## Contribution

It provides new insights into how mini-halos form dwarf-like objects and how environmental factors and gas cooling influence satellite survival and characteristics.

## Key findings

- Mini-halos form dwarf galaxy-like objects, not globular clusters.
- Gas cooling efficiency in mini-halos determines star formation success.
- Ram pressure and tidal forces disrupt satellites, especially near the host galaxy center.

## Abstract

We trace the cosmological origin of satellites around a dwarf galaxy using a very high resolution (12~pc/h) cosmological hydrodynamic zoom simulation. To realistically describe the formation and evolution of small-mass stellar satellites, our model includes a full baryonic physics treatment including a recipe for UV self-shielding. We find that the mini-halos form objects resembling dwarf galaxies. Despite our high resolution, none of our 'mini-halos' form objects that might be considered globular cluster-like. Instead such objects are formed in the host galaxy's gaseous disk. We investigate why some form stars more efficiently than others. We find that the majority of their star forming gas is accreted after reionisation, thus the survival of a mini-halo's gas to reionisation is not an important factor. Instead, the key factor seems to be the ability for a mini-halo to cool its recently accreted gas, which is more efficient in more massive halos. We find halos in denser environments suffer more mergers, enabling them to grow their mass such that cooling of accreted gas can occur efficiently. Although the host galaxy is only a dwarf galaxy itself, we find that ram pressure is an efficient means by which accreted mini-halos lose their gas content, both by interacting with hot halo gas but also in direct collisions with the gas disk of the host. The satellites are also disrupted by the tidal forces near the center of the host galaxy. Compared to the disrupted satellites, surviving satellites are relatively more massive, but tend to infall later into the host galaxy, thus reducing the time they are subjected to destructive environmental mechanisms and dynamical friction. In summary, our results suggest that the characteristics of satellites are mainly determined by their ability to efficiently cool gas that is accreted in the redshift range z=3-5, prior to their infall into the host galaxy.