Testing the framework of the halo occupation distribution with assembly bias modelling and empirical extensions

ABSTRACT We investigate theoretical systematics caused by the application of the halo occupation distribution (HOD) to the study of galaxy clustering at non-linear scales. To do this, we repeat recent cosmological analyses using extended HOD models based on both the Aemulus and Aemulus $\nu$ simulation suites, allowing for variations in the dark matter halo shape, incompleteness, baryonic effects, and position bias of central galaxies. We fit to the galaxy correlation function including the projected correlation function, redshift-space monopole and quadrupole, and consider how the changes in HOD affect the retrieval of cosmological information. These extensions can be understood as an evaluation of the impact of the secondary bias in the clustering analysis. In the application of BOSS (Baryon Oscillation Spectroscopic Survey) galaxies, these changes do not have a significant impact on the measured linear growth rate. However, we do find weak to mild evidence for some of the effects modelled by the empirical parametrizations adopted. The modelling is able to make the HOD approach more complete in terms of cosmological constraints. We anticipate that the future and better data can provide tighter constraints on the new prescriptions of the HOD model.