2017/12/21 by Charlotte Welker, Welker, Charlotte, Chris Power +9 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.1712.07818
openalex publication_date 2017/12/21 · openalex created_date 2022/08/29 · openalex updated_date 2026/07/28
The anisotropic distribution of satellites around the central galaxy of their\nhost halo is well-documented. However the relative impact of baryons and dark\nmatter in shaping this distribution is still debated. Using the simulation\nHorizon-AGN, the angular distribution of satellite galaxies with respect to\ntheir central counterpart and halo is quantified. Below one Rvir, satellites\ncluster more strongly in the plane of the central, rather than merely tracing\nthe shape of their host halo. This is due to the increased isotropy of inner\nhaloes acquired through their inside-out assembly in vorticity-rich flows along\nthe cosmic web. While the effect of centrals decreases with distance, halos'\ntriaxiality increases, impacting more and more the satellite's distribution.\nEffects become comparable just outside one virial radius. Above this scale, the\nfilamentary infall also impacts the satellites distribution, dominating above\ntwo virial radii. The central's morphology plays a governing role: the\nalignment w.r.t. the central plane is four times stronger in haloes hosting\nstellar discs than in spheroids. But the impact of the galactic plane decreases\nfor lower satellite-to-central mass ratios, suggesting this might not hold for\ndwarf satellites of the Local group. The orientation of the Milky-Way's\nsatellites traces their cosmic filament, their level of coplanarity is\nconsistent with systems of similar mass and cosmic location in Horizon-AGN.\nHowever, the strong impact of galactic planes in massive groups and clusters\nbounds the likelihood of finding a relaxed region where satellites can be used\nto infer halo shape. The minor-to-major axis ratios for haloes with\nlog(M0/Msun)>13.5 is underestimated by 10%. This error soars quickly to 30-40%\nfor individual halo measurements.\n