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 Title
 Observational constraints on FLRW, Bianchi type I and V brane models
 KIAS Author
 Davari, Z.
 Journal
 PHYSICS OF THE DARK UNIVERSE, 2024
 Archive

2407.15565
 Abstract
 This study explores the compatibility of Covariant Extrinsic Gravity (CEG), a braneworld scenario with an arbitrary number of noncompact extra dimensions, with current cosmological observations. We employ the chisquare statistic and Markov Chain Monte Carlo (MCMC) methods to fit the FriedmannLemaitreRobertsonWalker (FLRW) and Bianchi typeI and V brane models to the latest datasets, including Hubble, Pantheon+ Supernova samples, Big Bang Nucleosynthesis (BBN), Baryon Acoustic Oscillations (BAO), and the structure growth rate, f sigma 8(z). Parameters for FLRW universe consist Omega((b))(0),Omega((cd))(0),Omega((k))(0),H0,gamma,sigma(8), while for the Bianchi model are Omega((b))(0),Omega((cd))(0),Omega((k))(0),H0,gamma,sigma(8). By comparing our models to observational data, we determine the best values for cosmological parameters. For the FLRW model, these values depend on the sign of gamma (which gives the time variation of gravitational constant in Hubble time unit): gamma>0 yields gamma=0.000080.00011+0.00015, and Omega((k))(0)=0.014(+0.024)(0.022) and gamma<0 leads to gamma=0.0226(+0.0054)(0.0062), and Omega((k))(0)=0.023(+0.039)(0.041). It should be noted that in both cases Omega((k))(0)>0, which represents a closed universe. Similarly, for the Bianchi typeV brane model, the parameter values vary with the sign of gamma, resulting in gamma=0.00084(+0.00019)(0.00021), Omega((beta))(0)=0.0258(+0.0052)(0.0063), and Omega(theta)(0)(x10(5))=4.190.75+0.67 (as with the density parameter of stiff matter) for gamma>0, and gamma=0.001070.00020+0.00019, Omega((beta))(0)=0.0259(+0.0050)(0.0062), and Omega(theta)(0)(x105)=4.17(+0.91)(0.98) for gamma<0. In both cases Omega((beta))(0)>0, which represents the Bianchi typeV, because in the Bianchi typeI, beta=0. Subsequently, utilizing these obtained best values, we analyze the behavior of key cosmological parameters such as the Hubble parameter, deceleration parameter, distance modulus, equation of state, and density parameters that characterize both matter and the geometric component of dark energy, as functions of redshift. Our results notably show that the FLRW model with gamma<0 is more compatible with observational data than the Bianchi model, based on various statistical criteria.