Day 956

Monday.


1508.07012
Modelling galaxy clustering: halo occupation distribution versus subhalo matching
Guo, Zheng, Behroozi, Zehavi, et al

Model the luminosity-dependent projected and z-space 2PCFs of the SDSS DR7 Main galaxy sample, using the HOD model and the sub halo abundance matching (SHAM) model and its extension.  All the models are built on the same high-res N-body sims.  Find that the HOD model generally provides the best performance in reproducing the clustering measurements in both projected and z spaces. The SHAM model with the same halo-galaxy relation for central and satellite galaxies (or distinct haloes and sub haloes), when including scatters, has a best-fitting chi2/DOF around 2-3.  Therefore extend the SHAM model to the sub halo clustering and abundance matching (SCAM) by allowing the central and satellite galaxies to have different galaxy-halo relations.  Infer the corresponding halo/subhalo parameters by jointly fitting the galaxy 2PCFs and abundances and consider sub haloes selected based on three properties, the mass M_acc at the time of accretion, the maximum circular velocity V_acc at the time of accretion, and the peak maximum circular velocity V_peak over the history of the sub haloes.  The 3 sub halo models work well for luminous galaxy samples (with luminosity above L*).  For low-luminosity samples, the V_acc model stands out in reproducing the data, with the V_peak model slightly worse, while the M_acc model fails to fit the data.  Discuss the implications of the modeling results.


1508.07220
Angular momentum evolution for galaxies in a Lambda-CDM scenario
Pedrosa, Tissera

Galaxy formation in the current cosmo paradigm is a very complex process in which inflows, outflows, interactions and mergers are common events.  These processes can redistribute the angular momentum content of baryons.  Recent observational results suggest that disc formed conserving angular momentum while elliptical galaxies, albeit losing angular momentum, determine a correlation between the specific angular momentum of the galaxy and the stellar mass.  These observations provide stringent constraints for galaxy formation models in a hierarchical clustering scenario.  Aim to analyze the specific angular momentum content of the disc and bulge components as a function of virial mass, stellar mass and redshift.  Also estimate the size of the simulated galaxies and confront them with observations.  Use cosmo hydrodynamical simulations that include an effective physically-motivated Supernova feedback which is able to regulate the SF in haloes of different masses.  Analyse the morphology and formation history of a sample of galaxies in a cosmo sim by performing a bulge-disc decomposition of the analyse systems and their progenitors.  estimate the angular momentum content of the stellar and gaseous discs, stellar bulges and total baryons.  In agreement with recent observational findings, the simulated galaxies have disc and spheroid components whose specific angular momentum contents determine correlations with the stellar and DM masses with the same slope, although the spheroidal components are off-set by a fixed fraction.