The cosmological origin of the satellite distribution

Abstract

References •Azzaro M., Zentner A.R., Prada F., Klypin A. 2006, ApJ, 645, 228 •Brainerd T.G. 2005, ApJ, 628, L101 •Holmberg E. 1969, Ark.Astr., 5, 305 •Koch A., Grebel E.K. 2006, AJ, 131, 1405 •Lynden-Bell D. 1982, Obs., 102, 202 •Sales L., Lambas D.G., 2004, MNRAS, 384, 1236 •Serna A., Dominguez-Tenreiro R., Saiz A. 2003, ApJ, 597, 878 •Zaritsky D., Smiith R, Frenk C. White S.D.M. 1997, ApJ, 478,39 Satellite distribution: controversial observational results •Polar distribution satellite distribution perpendicular to the disc of the primary −Holmberg (1969): polar distribution in rich systems for distances dp 250kpc −Lynden-Bell (1982) and references thereafter: Satellites in the Milky Way in Great Circles perpendicular to the Galactic Plane −Koch & Grebel (2006): Satellites in M31 in orbits perpendicular to the disk •Planar distribution satellite distribution aligned with the disc of the primary −Sales & Lambas (2004): 3000 satellites of ~1500 isolated primaries in 2dFGRS −Brainerd (2005): planar distribution for satellites with dp<100 kpc, in isolated primaries, isotropy for 250<dp<500 kpc •Isotropy −Azzaro et al (2006): 144 spiral and 193 satellites in SSDS INTRODUCTION The distribution of satellite galaxies relative to their host has been subject of debate among several authors. Some of them have found polar alignment in the satellite distribution in disk galaxies, while others have obtained a planar distribution (along the major axis of the disk seen in projection). We analyze the distribution of satellite galaxies in cosmological self-consistent hydrodynamical simulations. Our conclusions are that: (1) the three dimensional satellite orbits present a polar distribution, and (2) the satellite distribution as a function of the projected distance is, at short distances, planar for isolated systems and polar for rich systems. ABSTRACT