摘要:
   Understanding how galaxies form and evolve is one of the most pressing questions in modern astronomy. The spatial distribution of galaxies as a function of galaxy properties encodes key information on the physical processes in galaxy formation and evolution. A better understanding of the distribution would rely on connecting galaxy properties to the underlying dark matter halos. In this talk, I will focus on the galaxy-halo connection extracted from galaxy catalogs with two different redshift sources: spectroscopic and photometric. From SDSS DR7 Main Galaxy Sample, we build a global connection between galaxy color/luminosity and halo mass, using the observed clustering of galaxies across the color-magnitude diagram and the theoretically predicted halo population. While for galaxy samples with photometric redshift, the direct measurements of galaxy clustering and the derived galaxy-halo connections would be incorrect. By assuming a Gaussian form of the photometric redshift uncertainties, we develop a method to simultaneously obtain the true galaxy-halo connections and the photometric redshift uncertainties. We then apply this method to galaxy samples from the currently largest galaxy catalog DESI Legacy Imaging Data Release 8 and find that the derived galaxy bias shows a clear color, luminosity, and redshift dependency. With the aid of galaxy-galaxy lensing measurements, we can break the degeneracy between galaxy bias and the matter fluctuation parameter $\sigma_8$. Our results show the $\sigma_8$ values constrained from the samples with different colors and luminosities in the same redshift bin agree with each other at a $\le 2\sigma$ level. After averaging the values in the same redshift bin, the $\sigma_8$ parameter increases as a function of redshift, from  $\sigma_8=0.65\pm 0.03$ at redshift $z=0.2$ gradually increasing to $\sigma_8=1.2\pm 0.3$ at redshift $z=0.8$.