Marcello Cacciato

Abstract: We use the conditional luminosity function (CLF) and data from the 2-degree Field Galaxy Redshift survey (2dFGRS) to constrain the average relation between light and mass in a Lambda cold dark matter (Lambda CDM) cosmology with Omega(m) = 0.23 and sigma(8) = 0.74 (hereafter WMAP3 cosmology). Reproducing the observed luminosity dependence of the galaxy two-point correlation function results in average mass-to-light ratios that are similar to 35 percent lower than those in a Lambda CDM cosmology with Omega(m), = 0.3 and sigma(8) = 0.9 (hereafter WMAP1 cosmology). This removes an important problem with previous halo occupation models which had a tendency to predict cluster mass-to-light ratios that were too high. For the WMAP3 cosmology, our model yields average mass-to-light ratios, central galaxy luminosities, halo occupation numbers, satellite fractions and luminosity-gap statistics, that are all in excellent agreement with those obtained from a 2dFGRS group catalogue and from other independent studies. We also use our CLF model to compute the probability distribution P(M vertical bar L-cen), that a central galaxy of luminosity L-cen resides in a halo of mass M. We find this distribution to be much broader than what is typically assumed in halo occupation distribution models, which has important implications for the interpretation of satellite kinematics and galaxy-galaxy lensing data. Finally, reproducing the luminosity dependence of the pairwise peculiar velocity dispersions in the 2dFGRS requires relatively low mass-to-light ratios for clusters and a satellite fraction that decreases strongly with increasing luminosity. This is only marginally consistent with the constraints obtained from the luminosity dependence of the galaxy two-point correlation function. We argue that a cosmology with parameters between those of the WMAP1 and WMAP3 cosmologies is likely to yield results with a higher level of consistency.

TL;DR: In this article, the authors used the conditional luminosity function (CLF) and data from the 2dFGRS to constrain the average relation between light and mass in a LCDM cosmology with Omegam=0.23 and sigma_8 = 0.74.

TL;DR: In this article, the authors use analytic estimates of the inflow for a self-regulated unstable disk at a Toomre stability parameter Q~1, and isolated galaxy simulations capable of resolving the nuclear inflow down to the central parsec.

TL;DR: In this paper, the link between galaxy luminosity and dark matter halo mass was established using the conditional luminosity function (CLF), which gives the number of galaxies with luminosities in the range L +/- dL/2 that reside in a halo of mass M. The resulting CLF models are used to predict the galaxy-galaxy lensing signal.

TL;DR: In this article, a conditional luminosity function (CLF) was used to constrain the parameters of the galaxy-galaxy lensing signal, and the luminosity dependence of the correlation lengths of galaxies.