Spatial and kinematic alignments between central and satellite halos

Abstract

Based on a cosmological N-body simulation we analyze spatial and kinematic alignments of satellite halos within six times the virial radius of group size host halos (Rvir). We measure three different types of spatial alignment: halo alignment between the orientation of the group central substructure (GCS) and the distribution of its satellites, radial alignment between the orientation of a satellite and the direction towards its GCS, and direct alignment between the orientation of the GCS and that of its satellites. In analogy we use the directions of satellite velocities and probe three further types of alignment: the radial velocity alignment between the satellite velocity and connecting line between satellite and GCS, the halo velocity alignment between the orientation of the GCS and satellite velocities and the auto velocity alignment between the satellites orientations and their velocities. We find that satellites are preferentially located along the major axis of the GCS within at least 6 Rvir (the range probed here). Furthermore, satellites preferentially point towards the GCS. The most pronounced signal is detected on small scales but a detectable signal extends out to 6 Rvir. The direct alignment signal is weaker, however a systematic trend is visible at distances < 2 Rvir. All velocity alignments are highly significant on small scales. Our results suggest that the halo alignment reflects the filamentary large scale structure which extends far beyond the virial radii of the groups. In contrast, the main contribution to the radial alignment arises from the adjustment of the satellite orientations in the group tidal field. The projected data reveal good agreement with recent results derived from large galaxy surveys. (abridged)

accepted for publication in ApJ

References in corpus (6)

• The Evolution of Dark Matter Halo Properties in Clusters, Filaments, Sheets and Voids
• Spin alignment of dark matter haloes in filaments and walls
• The shapes, orientation, and alignment of Galactic dark matter subhalos
• Three Different Types of Galaxy Alignment within Dark Matter Halos
• Radial Alignment in Simulated Clusters
• The Alignment between Satellites and Central Galaxies: Theory vs. Observations

Cited by in corpus (5)

• Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite Luminosity Function
• The spin and orientation of dark matter halos within cosmic filaments
• Alignment between galaxies and large-scale structure
• Alignments of Group Galaxies with Neighboring Groups
• The radial alignment of dark matter subhalos: from simulations to observations