Observational Tests for the Cosmological Principle and World Models
Abstract
We review observational tests for the homogeneity of the Universe on large scales. Redshift and peculiar velocity surveys, radio sources, the XRay Background, the Lyman$\alpha$ forest and the Cosmic Microwave Background are used to set constraints on inhomogeneous models and in particular on fractallike models. Assuming the Cosmological Principle and the FRW metric, we estimate cosmological parameters by joint analysis of peculiar velocities, the CMB, cluster abundance, IRAS and Supernovae. Under certain assumptions the best fit density parameter is Omega_m = 1  lambda \approx 0.4 . We present a new method for joint estimation by combining different data sets in a Bayesian way, and utilising `HyperParameters'.
 Publication:

Structure Formation in the Universe
 Pub Date:
 2001
 arXiv:
 arXiv:astroph/0001061
 Bibcode:
 2001ASIC..565..131L
 Keywords:

 Astrophysics
 EPrint:
 Review talk, to appear in the proceedings of the NATO ASI `Structure Formation in the Universe', Isaac Newton Institute, Cambridge, July 1999, ed. R. Crritenden &