Mathematical Modelling and Geometry
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Published By Tver State University

2311-1275

2020 ◽  
pp. 1-13
Author(s):  
Saha Bijan

We studied nonlinear spinor fields in the framework of a static spherically symmetric space-time. In doing so we have suggested a rather simple method to solve the corresponding Einstein equations. As an example, a nonlinear spinor field was considered. The corresponding equations were solved analytically and numerically.


2020 ◽  
pp. 1-20
Author(s):  
G.S. Sharov ◽  
E.S. Sinyakov

We analyze how predictions of cosmological models depend on a choice of described observational data, restrictions on flatness, and how this choice can alleviate the H tension. These effects are demonstrated in the wCDM model in comparison with the standard ΛCDM model. We describe the Pantheon sample observations of Type Ia supernovae, 31 Hubble parameter data points H(z) from cosmic chronometers, the extended sample with 57 H(z) data points and observational manifestations of cosmic microwave background radiation (CMB). For the wCDM and ΛCDM models in the flat case and with spatial curvature, we calculate χfunctions for all observed data in different combinations, estimate optimal values of model parameters and their expected intervals. For both considered models the results essentially depend on a choice of data sets. In particular, for the wCDM model with H(z) data, supernovae and CMB the 1σ estimations may vary from H = 67.52km /(s·Mpc) (for all N = 57 Hubble parameter data points) up to H = 70.87 /(s·Mpc) for the flat case (k = 0) and N = 31. These results might be a hint how to alleviate the problem of H tension: different estimates of the Hubble constant may be connected with filters and a choice of observational data.


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