STUDY OF UNIVERSE WITH DARK SECTOR INTERACTIONS TO RESOLVE TENSION IN THE MEASUREMENTS OF HUBBLE CONSTANT (H0)

• Main Author: Rafif Rabbani, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/49203
• Institution: Institut Teknologi Bandung

CDM is the standard model of big bang cosmology. In this model the dominant components of the universe are dark energy in the form of cosmo- logical constant (), dark matter in the form of cold dark matter (CDM), and baryonic matter. Dark energy and dark matter comprise about 95% of the total density of the universe and they are often classied as the dark sector. Despite its successes in explaining numerous observational results, CDM still has several problems that are yet to be solved. Therefore the possibility that the dark sector takes other forms is still open. Around 2014 there was an indication of an emerging problem in cosmol- ogy. Researchers found a discrepancy in the measured value of the Hubble constant (H0) from two independent methods, namely the cosmic distance ladder method and the cosmological method. Currently the discrepancy is at 4:4 and it is often referred as the H0 tension. One possible cause of this ten- sion is the existence of new physics beyond CDM. One of the proposed new physics is the presence of a non-gravitational interaction within dark sector components. This Final Project discusses the cosmic dynamics for the general phe- nomenological interaction model Q = 3H(cc + xx). We nd that at the background level, such model may give the appropriate sequence of evolution as indicated by observations, which is a universe initially radiation-dominated, followed by matter domination, and nally dark energy domination. We also derived the cosmic dynamics at linear perturbation level for scalar mode. We modied the Boltzmann solver CAMB to obtain the CMB and matter power spectra for the cases Q = 3Hcc and Q = 3Hxx. We nd that the presence of interaction aects the amplitude and the position of the acoustic peaks of the CMB power spectra on all scales. We also nd that interaction of the form Q = 3Hxx with energy transfer from dark energy to dark matter and wx < ????1 may help alleviate the H0 tension.