STUDI EVOLUSI PARAMETER HUBBLE H(Z) DENGAN MENGGUNAKAN METODE INVERSE DISTANCE LADDER

• Main Author: Izdihar Nafisyahrin, Hana
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/49872
• Institution: Institut Teknologi Bandung

Discrepancies between Hubble constant H0 value inferred from local distance ladder and CMB anisotropic analysis at high redshift assuming CDM model (cosmological approach) has led cosmologists to start questioning about the validity of CDM model at low redshift. The most recent distance ladder result obtained by Riess et. al. (2019) has increased the tension with global measurement by Planck Collaboration (2018) to 4.4. In order to reduce this tension, several ideas have been proposed including suppressing measurement uncertainties, using independent method (gravitational lensing and Sunyaev-Zeldovich effect), or proposing modifications on the physical basis for instance allowing dark matter and dark energy to interact with each other or adding new neutrino species. In this Final Project H0 will be determined through the use of inverse distance ladder following a previous work by Lemos et al. (2019) using Bayesian inference. In principle this method is similar to the conventional distance ladder, except that it uses a calibrator that originates from an earlier epoch, that is the sound horizon radius rd obtained by WMAP dan Planck Collaboration (2018). The use of this calibrator implicitly justifies the validity of CDM model at high redshift. Nevertheless, this Final Project also uses a parameterization model that quantifies Hubble parameter H(z) evolution at low redshift, therefore the final shape is directly constrained by observational data that allows for deviation from the standard model CDM. The data used in the analysis are angular diameter distance and Hubble distance that come from several BAO surveys and the corrected apparent magnitude of supernova Ia by Patheon. The results obtained match CDM model results more than distance ladder's. H0 inferred from epsilon and log model respectively are higher 2.45 dan 2.43 from the value preferred by Planck Collaboration (2018) and lower 2.94 and 2.87 relative to value obtained by Riess et al. (2018) for Planck rd. On the other hand for WMAP rd, the H0 values obtained in the case of epsilon and log model are higher by 1.47 and 1.41 from Planck value and lower by 3.11 and 3.15 from Riess et. al. (2019) result. This Final Project also confirm the consistency between rd value from CMB analysis and rd inferred from deuterium abundance measurements and BBN prediction. It is obtained that the Planck Collaboration (2018) rd diers from rd BBN at 1.35 and 1.91 depending on the bh2 prior used.