DETERMINING THE LOCAL DARK MATTER DENSITY USING GAIA DR2

• Main Author: Dafa Wardana, Mochammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/39457
• Institution: Institut Teknologi Bandung

Dark matter is believed to comprise about 26.4 % of the total mass-energy content of the universe, more than baryonic matter which is only about 4.9 % (Planck Collaboration et al., 2018). Although these results indicate that the amount of dark matter is abundant, properties of dark matter are still unknown in detail. Therefore, various attempts are tried to gain better understanding of the properties of dark matter. One of the attempts which is to conduct direct experiment, i.e. detecting the interaction of dark matter particles with nuclei in the detector materials. The experiments require the value of the local dark matter density to estimate detection rate of the interaction of dark matter particles with the detector materials. One way that can be used to determine the local dark matter density is by considering the motion of objects in the Solar neighborhood, which will be called tracers. In this Final Project, determination of the local dark matter density was performed by considering the motion and number density of a star population in a cylindrical space with a radius of 150 pc and half-height of 200 pc. The data of star motion and number density are calculated using Gaia DR2 downloaded from the Gaia Archive site, i.e. https://gea.esac.esa.int/archive/. K dwarf stars are selected as tracers and data was selected based on the range of absolute visual magnitude MV and the eective temperature of K dwarfs. The Jeans and Poisson equations are used to connect the observed quantities, the velocity and number density of tracers, with the local dark matter density. Tracers are assumed to be in dynamic equilibrium and their number density as a function of height follows an exponential prole. Marginalization of the local dark matter density was done with the Bayesian theorem using the Markov Chain Monte Carlo (MCMC) method. Determination of the local dark matter density in this Final Project gives a result of dm = 0:01160:0012 M/pc3 or dm = 0:4390:046 GeV/cm3.