Eyal Neistein Dec 2012 MS workshop Modeling galaxy clustering and weak gravitational lensing with the Millennium simulation Eyal Neistein TMoX group, MPE Garching Collaborators: Mike Boylan-Kolchin, Sadegh Khochfar, Cheng Li, Francesco Shankar, Simone Weinmann

Eyal Neistein Dec 2012 MS workshop Halo occupation distribution (HOD) models No evolution with time, deal with only one redshift Populate N galaxies inside each halo of mass M A specific population of galaxies (usually more massive than M min ) Halo properties (density profile, clustering) are being used to compute galaxy properties

Eyal Neistein Dec 2012 MS workshop HOD principles Model assumptions: Number of galaxies per halo, P(N|M) Location of satellite galaxies within their host halo follows NFW. Jing, Mo, & Borner (1998); Ma & Fry (2000); Peacock & Smith (2000); Seljak (2000); Scoccimarro et al. (2001); Berlind & Weinberg (2002); Cooray & Sheth (2002); Yang, Mo, & van den Bosch (2003); Kravtsov et al. (2004); Tinker et al (2005,2011); Zheng et al. (2005, 2007); Zehavi et al (2005,2010)… Zehavi et al (2010) Main features: Analytic model, self-contained A simple set of parameters A priori functional shapes Not fully accurate (e.g., the assembly bias, Gao et al. 2005)

Eyal Neistein Dec 2012 MS workshop The HASH * approach 2. Allow a different stellar mass for central and satellite galaxies Neistein et al (2011a, 2011b) - Dynamical friction for galaxies (once subhalo are stripped below the resolution) - Location of satellite galaxies (according to the most-bound particle, or analytic model) 1. Assign a stellar mass to each subhalo from the Millennium simulation (M infall ) * halo and subhalo 3. The stellar mass of satellite galaxies depends on both M infall and M 200 : SAM constant stellar mass

Eyal Neistein Dec 2012 MS workshop Parameter-free approach The observed CFs: different bins of stellar mass Satellites: Stellar mass M infall Centrals: do not assume a functional form check all possibilities

Eyal Neistein Dec 2012 MS workshop Searching all solutions ~10 7 subhalos within the Millennium simulation ~10 14 number of pairs ~10 10 models to test ~10 24 computer operations => Hubble time? Correlation function: we compute the number of subhalo pairs : central-central pairs with subhalo masses M 1 infall, M 2 infall, : satellite-satellite, central-satellite Weak gravitational lensing: we compute the projected density profile around each subhalo, and average it:

Eyal Neistein Dec 2012 MS workshop Models that fit the CF & SMF Neistein et al (2011b) median 1-std full range Satellites only:

Eyal Neistein Dec 2012 MS workshop Results, weak lensing Centrals (uniform errors) Satellites (uniform errors) Centrals, 95% level Centrals, Mandelbaum et al. (2006), HOD Reference line

Eyal Neistein Dec 2012 MS workshop All constraints together -Weak lensing does not contribute -Freedom for massive satellites -Future weak lensing measurements

Eyal Neistein Dec 2012 MS workshop Comparison to HODs

Eyal Neistein Dec 2012 MS workshop Thank you, the Millennium team! Summary We develop a new approach (HASH) - stellar mass (for satellites) depends on both halo & subhalo - freedom in satellite locations - dynamical friction with a free scaling constant >> more freedom in the models >> higher accuracy >> (almost) parameter free The relation between dark-matter & galaxies -weak lensing does not add much for massive galaxies -systematics are still important (assembly bias)