The spin bias of dark matter halos

Author(s)

Beatriz Tucci Schiewaldt

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Física (IF/SBI)
• Defense date: 2021-10-05

Examining board members

Luis Raul Weber Abramo; Andrés Balaguera Antolínez; Ravi Kiran Sheth

• Advisor: Luis Raul Weber Abramo

Abstract

The dependence of dark matter halo bias on spin at fixed mass is known as spin bias. However, although at the high-mass end the higher-spin halos have a higher bias than their lower-spin counterparts, this trend inverts for low-mass halos. We have recently clarified this complex scenario, showing that this inversion of the mass dependence of spin bias can be completely explained by the population of splashback halos -- i.e., halos that at some point in the past fell inside the virial radius of another halo (typically, a larger-mass halo), but then exited that parent halo. This dependence of spin bias on splashback halos was first explained in the recent paper Tucci et al. (2021). What we found is that, when this specific population is excluded from the sample, only the intrinsic spin bias signal remains -- i.e., a higher bias for higher-spin halos. Now that we understood the low-mass feature, our goal is to shed light onto the physical origins of the high-mass, intrinsic spin bias. In order to connect halo spin to its bias in a single analytical framework, we investigate the main theories for halo angular momentum and halo bias. We also explore how this mechanism, which is more readily studied via halos in N-body simulations, can be extended to galaxies in the context of the halo-galaxy connection framework and galaxy formation. Finally, we study possible consequences for observational cosmology. (AU)

• FAPESP's process: 20/10520-5 - The tidal field as a mediator between dark matter halo spin and its large-scale bias
• Grantee: Beatriz Tucci Schiewaldt
• Support Opportunities: Scholarships in Brazil - Master