Constraining galaxy formation and cosmology with the conditional luminosity function of galaxies

Abstract

We use the conditional luminosity function Φ(L | M) dL, which gives the number of galaxies with luminosities in the range L± d L/2 that reside in a halo of mass M, to link the distribution of galaxies to that of dark matter haloes. Starting from the number density of dark matter haloes predicted by current models of structure formation, we seek the form of Φ(L | M) that reproduces the galaxy luminosity function and the luminosity dependence of the galaxy clustering strength. We test the models of Φ(L | M) by comparing the resulting mass‐to‐light ratios with constraints from the Tully–Fisher (TF) relation and from galaxy clusters. A comparison between model predictions and current observations yields a number of stringent constraints on both galaxy formation and cosmology. In particular, this method can break the degeneracy between Ω0 and the power‐spectrum normalization σ8, inherent in current weak‐lensing and cluster‐abundance studies. For flat ΛCDM cosmogonies with σ8 normalized by recent weak gravitational lensing observations, the best results are obtained for Ω0∼ 0.3; Ω0≲ 0.2 leads to too large galaxy correlation lengths, while Ω0≳ 0.4 gives too high mass‐to‐light ratios to match the observed TF relation. The best‐fitting model for the ΛCDM concordance cosmology with Ω0= 0.3 and ΩΛ= 0.7 predicts mass‐to‐light ratios that are slightly too high to match the TF relation. We discuss a number of possible effects that might remedy this problem, such as small modifications of σ8 and the Hubble parameter with respect to the concordance values, the assumption that the Universe is dominated by warm dark matter, systematic errors in current observational data, and the existence of dark galaxies. We use the conditional luminosity function derived from the present data to predict several statistics about the distribution of galaxy light in the local Universe. We show that roughly 50 per cent of all light is produced in haloes less massive than 2 × 1012h−1 M⊙. We also derive the probability distribution P(M | L) dM that a galaxy of luminosity L resides in a halo with virial masses in the range M± dM/2.

The Dark Side of the Halo Occupation Distribution

“…This is comparable to the observed fraction of $20% of galaxies located in groups and clusters. Yang et al 2003). The model has quickly proven to be a very convenient analytic formalism for predicting and interpreting the nonlinear clustering of dark matter and galaxies.…”

Formation of disc galaxies in preheated media: a preventative feedback model

“…Surveys in radio bands, such as HIPASS (Meyer et al 2004;Zwaan et al 2004) and ALFALFA (Giovanelli et al 2005b,a), have also made it possible to estimate the cold gas mass function of local galaxies, providing a complete census of the cold baryonic contents of present-day galaxies. Combined with the halo mass function predicted by the current ΛCDM model, these data can be used to statistically establish connections between galaxies and their host dark matter halos (Yang, Mo & van den Bosch 2003;Conroy, Wechsler & Kravtsov 2006;Yang et al 2012Yang et al , 2013Behroozi, Conroy & Wechsler 2010;Behroozi, Wechsler & Conroy 2013;Moster, Naab & White 2013;Lu et al 2013c;Reddick et al 2013). This type of study has produced important results for the luminosity/stellar mass -halo mass relation, the cold gas mass -halo mass relation, and the star formation and stellar mass assembly histories in halos of different masses.…”

Velocity of galaxies with different luminosity

“…The M ⋆ like galaxies are rather moderate in their PVD, and probably reside in galaxy size halos. The thick solid line represents the prediction based on the up-to-date halo model of Yang et al (2003). For the halo model, we adopt the cosmological model that is a currently popular flat low-density model with the density parameter Ω 0 = 0.3 and the cosmological constant λ 0 = 0.7 (LCDM).…”