Speaker
Description
Secondary bias reflects the fact that large-scale clustering of haloes at a given mass varies significantly with their secondary properties. Recent studies identify tidal anisotropy, defined on intermediate scales, as the primary driver of secondary bias. Essentially, the tidal field is tightly intertwined with the large-scale matter distribution. In this work, we investigate the intricate relationships between secondary bias, matter anisotropy, and tidal anisotropy. Firstly, to depict the relation between secondary bias and matter anisotropy. we quantify the anisotropic secondary bias (ASB), exploring how secondary bias relates to halo orientation. We find that ASB is insignificant for concentration, formation time, and triaxiality but is pronounced for spin and the minor-to-major axis ratio. This indicates that halos with slower rotation or more elongated shapes tend to align with filaments, while other halo properties show no such correlation with alignment. Furthermore, we find that matter anisotropy (alignment) itself cannot explain the secondary bias. Moreover, tidal anisotropy emerges as the primary driver of secondary bias, including the alignment bias, but it plays a negligible role in the ASB. These findings underscore the complex interplay between the cosmic web and internal halo properties. Moreover, we observe that the halo definition partially influences secondary bias, particularly spin bias at the low-mass end, offering deeper insights into the physical origins of spin bias. Nevertheless, the halo definition has minimal impact on anisotropic secondary bias. Our findings emphasize the significant influence of halo anisotropy and definitions of secondary bias, related to the halo statistics, galaxy-halo models, and cosmological measurement.
