UC Santa Cruz

In the modern Lambda-CDM model of cosmology, galaxies form in the centers of overdense regions in the cosmic web, known as dark matter halos. The formation and evolution of galaxies are believed to be connected to the formation and evolution of the halos they occupy. This concept is referred to as the galaxy--halo connection, and it provides us with an avenue for understanding the complex physics involved in galaxy formation. Because we assume every galaxy is located in the center of a halo, drawing parallels between the spatial distributions of galaxies and halos is an effective way of illuminating how halo properties may be connected to galaxy properties. However, three-dimensional spatial information is difficult to obtain accurately in the real Universe, as all information must be extracted from the emitted light of distant galaxies. In this paper, we apply the stochastic order redshift technique (SORT) to mock redshift surveys to test how well it recovers the true distribution of galaxies. SORT relies on a small (10%) reference sample of high-quality redshifts that outline the underlying structure of galaxies to determine new estimates of low-quality redshifts. We find that SORT overall improves redshifts, recovers the redshift-space clustering on scales > 2.5 Mpc/h, and provides improved estimates of local densities. Then, we study the clustering properties of central SDSS galaxies as a function of specific star formation rate (sSFR). We find that central galaxy auto-correlations show little dependence on sSFR, with the established result of quiescent galaxies clustering more strongly than star-forming galaxies attributable to satellites. Because halo assembly history is known to affect distinct halo clustering, this result implies there is little net correlation between halo assembly history and central galaxy sSFR. We also find that cross-correlations of centrals with satellites increase with lower sSFR, suggesting that quiescent centrals have more satellites than star-forming centrals of the same mass. We compare our findings to the predictions of empirical models of sSFR using the Bolshoi-Planck N-body simulation and find that models dependent on halo assembly history disagree with observations while a model independent of halo assembly history reproduces well the observed clustering properties of centrals.