Simulating tidal streams in a high resolution dark matter halo

TL;DR

This study simulates tidal streams in a high-resolution dark matter halo, comparing smooth and lumpy halos to understand the impact of substructures on stream morphology, revealing complex dependencies on initial conditions.

Contribution

It introduces a method to compare tidal streams in realistic lumpy halos versus smooth models without assuming idealized profiles, using the VL-2 simulation data.

Findings

Different initial velocities lead to significantly different stream morphologies.

Realistic substructure influences tidal stream development in complex ways.

The model provides new insights into tidal stream behavior beyond idealized assumptions.

Abstract

We simulate tidal streams in the presence and absence of substructures inside the zero redshift snapshot of the Via Lactea II (VL-2) simulation. A halo finder is used to remove and isolate the subhalos found inside the high resolution dark matter halo of VL-2, and the potentials for both the main halo and all the subhalos are constructed individually using the self-consistent field (SCF) method. This allows us to make direct comparison of tidal streams between a smooth halo and a lumpy halo without assuming idealized profiles or triaxial fits. We simulate the kinematics of a star cluster starting with the same orbital position but two different velocities. Although these two orbits are only moderately eccentric and have similar apo- and pericentric distances, we find that the two streams have very different morphologies. We conclude that our model of the potential of VL-2 can provide insights about tidal streams that have not been explored by previous studies using idealized or axisymmetric models.