The origin in spin in dark matter halos

• Grant number: 21/01836-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2021
• End date: January 31, 2022
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
• Principal Investigator: Luis Raul Weber Abramo
• Grantee: Danilo Bissoli Apendino
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Modern cosmology places great emphasis on galaxy surveys as tools for testing models and finding answers to two of the big science questions of our time: what are dark matter and dark energy. However, our observations are limited to objects that emit, absorb or reflect light, such as galaxies, quasars, Hydrogen clouds, etc. It is believed that these luminous objects "trace" the total matter density up to a bias. However, there are open issues with that association. One of the problems with this program is the origin of galaxy bias and the origin of the bias of the dark matter halos where those galaxies reside. It is known that the larger the halo mass, the greater is the bias. However, in recent years it has been understood that mass is not the only driver of bias: as shown recently by us [SATO-POLITO et al.,2018; MONTERO-DORTA et al., 2020; TUCCI et al., 2021], there are several other factors that affect bias, including the concentration of the density profile, the spin of the halo, and the age of the object (the time when it accreted most of its mass).In this project, we will study some kinematic and dynamical properties of dark matter halos since early times, when structure growth was still nearly linear, until recent times when nonlinearities are dominant. In order to study these halo properties at different times, we will employ analytical and numerical tools. From the analytical side, we will study the halo model and how the density peaks give rise to halos [COORAY; SHETH, 2002], as well as the relation between the bias of those halos and the properties of the matter density field in their vicinities [DESJACQUES; JEONG; SCHMIDT, 2018]. On the numerical side, we will employ the suite of N-body simulations MultiDARK (), which is one of the most complete cosmological simulations on the market, with plenty of snapshots of the same volume. Our group has worked extensively with those simulations, and the student will be able to take advantage of the know-how developed by many of his colleagues. Our goal is to first characterize the kinematic and dynamic properties of the halos as they first form; then, we will find correlations between those features and the properties of the initial density field, which at early times is well described by Gaussian initial conditions. (AU)