We study the Bianchi-I cosmological model motivated by signals of statistical isotropy violation seen in cosmic microwave background (CMB) observations and others. To that end, we consider various kinds of anisotropic matter that source anisotropy in our model, specifically cosmic strings, magnetic fields, domain walls and Lorentz violation generated magnetic fields. These anisotropic matter sources, taking one at a time, are studied for their co-evolution with standard model (isotropic) sources viz., dust-like (dark/normal) matter and dark energy modelled as cosmological constant. We constrain the Hubble parameter, density fractions of anisotropic matter, isotropic cold dark matter (CDM) and dark energy ($\Lambda$) in a Bianchi-I universe with planar symmetry i.e., with a global ellipsoidal geometry, and try to find signatures of a cosmic preferred axis if any. Pantheon Type Ia Supernova (SNIa) data is used in our study to obtain constraints on cosmological parameters of this model. In our analysis, we found a cosmic axis of anisotropy using SN1e data. Interestingly this preferred axis lies in the same direction, broadly, as some other cosmic anisotropy axes reported in the literature such as the CMB hemispherical power asymmetry, etc., with some of anisotropic sources considered. We also found a non-zero evidence for cosmic shear and eccentricity for our universe with those sources. To be more conclusive, we require more SNIa host galaxy data for tighter constraints on distance and absolute magnitude calibration which we hope will be available from the future JWST observations and other surveys.
Comment: 26 pages, 5 figures, 3 tables. Comments are welcome