The tidal streams of disrupting subhaloes in cosmological dark matter haloes

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-fitting 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 the 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 masses associated with the 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 characterized by a complex mass accretion history, an asymmetric mass distribution and the abundance of substructure. Finally, we confirm that the so-called 'backsplash' subhalo population is present not only in galaxy cluster haloes but also in galaxy haloes. The orbits of backsplash subhaloes brought them inside the virial radius of their host at some earlier time, but they now reside in its outskirts at the present-day, beyond the virial radius. Both backsplash and bound subhaloes experience similar mass loss, but the contribution of the backsplash subhaloes to the overall tidal debris field is negligible.