Slide 1

Galaxy Formation in a Cold Dark Matter Universe Mario G. Abadi Instituto de Astronoma Terica y Experimental Observatorio Astronmico de la Universidad Nacional de Crdoba Consejo de Investigaciones Cientficas y Tcnicas, Argentina In collaboration with Julio Navarro, Matthias Steinmetz, Vince Eke Amina Helmi, Laura Sales and Andres Meza XII Reunion Regional Latinoamericana de Astronoma de la IAU Isla de Margarita, Venezuela October 22-26 2007 Slide 2 Milky Way Galaxy Slide 3 Surviving Satellites Duncan Forbes 2007 Slide 4 Merging Satellites Sagittarius stream: warp around the entire MW nearly perpendicular to the midplane (Ibata et al. 2001). Progenitor=Sagittarius dwarf Monoceros ring: a proposed ring of stars around the galactic plane (Yanny et al 2003 & Ibata et al 2003). Progenitor=Canis Major dwarf? Orphan stream: a tidal stream that extends over 50 in the north galactic cap (Belokurov et al 2007). Progenitor=Ursa Major II?? Andromeda stream: a giant stream of stars uncovered in the halo of M31 (Ibata et al. 2001) External galaxy: a dwarf satellite galaxy in the process of being torn apart by gravitational tidal forces (Forbes et al 2003) Slide 5 Merged Satellites Substructure in the galactic halo (Helmi et al. 1999) Arcturus stream (Eggen 1971, Navarro et al. 2004) Debris from omega Cen parent galaxy in the solar neighborhood (Meza et al. 2005) Substructure in the galactic disk (Helmi et al. 2005) Slide 6 Slide 7 Orbital Classification of Satellites Surviving: Rgalaxy