The Tidal Streams of Disrupting Subhaloes in Cosmological Dark Matter Haloes

TL;DR

This paper analyzes the properties of tidal streams from disrupting subhaloes in cosmological dark matter haloes, proposing methods to infer progenitor properties like infall mass and eccentricity from stream characteristics.

Contribution

It introduces novel techniques to recover subhalo infall parameters from tidal stream data and automates the identification of stream arms based on energy distribution.

Findings

Infall mass can be estimated from the scatter of stream particles.

Radial velocity spread correlates with infall eccentricity.

Leading and trailing arm masses differ significantly.

Abstract

(abridged) We present a detailed analysis of the properties of tidally stripped material from disrupting substructure haloes or subhaloes in a sample of high resolution cosmological N-body host haloes ranging from galaxy- to cluster-mass scales. We focus on devising methods to recover the infall mass and infall eccentricity of subhaloes from the properties of their tidally stripped material (i.e. tidal streams). Our analysis reveals that there is a relation between the scatter of stream particles about the best-fit debris plane and the infall mass of the progenitor subhalo. This allows us to reconstruct the infall mass from the spread of its tidal debris in space. We also find that the spread in radial velocities of the debris material (as measured by an observer located at the centre of the host) correlates with the infall eccentricity of the subhalo, which allows us to reconstruct its orbital parameters. We devise an automated method to identify leading and trailing arms that can, in principle at least, be applied to observations of stellar streams from satellite galaxies. This method is based on the energy distribution of material in the tidal stream. Using this method, we show that the mass associated with leading and trailing arms differ. While our analysis indicates that tidal streams can be used to recover certain properties of their progenitor subhaloes (and consequently satellites), we do not find strong correlations between host halo properties and stream properties. This likely reflects the complicated relationship between the stream and the host, which in a cosmological context is characterised by a complex mass accretion history, an asymmetric mass distribution and the abundance of substructure. [...]