Master Thesis defense By Kevin Kumar

Titel:  Constraining the Hubble constant from structural and dynamical analysis of the Leo I group

Abstract: Two different approaches are traditionally used to determine the Hubble constant. The
discrepancy of the value obtained from each approach has rendered astronomers perplexed
over the past few years. Recent observations of the Leo I group reveal conflicting
conclusions about its dynamics and structure. Using high-precision TRGB-based measurements
of the Leo I group, it is possible to re-analyse its structure and provide a
distance ratio between the group and the Coma cluster through a revised Fundamental
Plane. The estimated distance to the Coma cluster is DComa = (99  2 (stat)  3 (sys))
Mpc. The peculiar velocity of Coma is obtained through low-redshift Universe reconstruction.
This provides a corrected observed velocity of Coma in the CMB rest-frame
of vComa = (7190  160) kms􀀀1. The resulting value of the Hubble constant is H0 =
(74  2 (stat)  3 (sys)) kms􀀀1Mpc􀀀1, which is in good agreement with recent type Ia
SNe and Cepheid-based estimates.