Brane universes tested against astronomical data

We discuss observational constrains coming from supernovae imposed on the behaviour of the Randall-Sundrum models. We test the models using the Perlmutter SNIa data as well as the new Knop and Tonry/Barris samples. The data indicates that, under the assumption that we admit zero pressure dust matter on the brane, the cosmological constant is still needed to explain current observations. We estimate the model parameters using the best-fitting procedure and the likelihood method. The observations from supernovae give a large value of the density parameter for brane matter Q(lambda,0) similar or equal to 0.01 as the best fit. For high redshifts z > 1.2, the difference between the brane model and the ACDM (Perlmutter) model becomes detectable observationally. From the maximum likelihood method we obtained the favored value of Omega(lambda,0) = 0.004 +/- 0.016 for Omega(k,0) = 0 and Omega(m,0) = 0.3. This gives the limit Omega(lambda,0) < 0.02 at 1sigma level. While the model with brane effects is preferred by the supernovae type la data, the model without brane fluid is still statistically admissible. We also discuss how fit depends on restrictions of the sample, especially with respect to redshift criteria. We also pointed out the property of sensitive dependence of results with respect to the choice of M parameter. For comparison the limit on brane effects which comes from CMB anisotropies and BBN is also obtained. The uncertainty in the location of the first peak gives a stronger limit Omega(lambda,0) < 1.0 x 10(-12) whereas from BBN we obtain that Omega(lambda,0) < 1.0 x 10(-27). However, both very strict limits are obtained with the assumption that brane effects do not change the physics in the pre-recombination era, while the SNIa limit is model independent. We demonstrate that the fit to supernovae data can also be obtained if we admit the phantom matter p = -(4/3)rho on the brane, where this matter mimics the influence of the cosmological constant. We show that phantom matter enlarges the age of the universe on the brane which is demanded in cosmology. Finally, we propose to check for dark radiation and brane tension by the application of the angular diameter of galaxies minimum value test.