What are the observational limits on the homogeneity of matter at large distances given that we can only observe matter on our backward light cone? The isotropy of the cosmic background radiation puts some constraints on the matter homogeneity at the time of decoupling. What does this tell us?
The isotropy of the cosmic background radiation puts some constraints on the matter homogeneity at the time of decoupling. What does this tell us?
Yu. V. Baryshev
ResponderEliminarDear All:
The question about inhomogeneous Universe really very fundamental.
If there is no homogeneous MATTER distribution then there is no foundation of Big Bang model.
The only direct test of actual matter distribution at scales from 1 Mpc to 1000 Mpc is the observations of spatial distribution of galaxies and quasars in huge surveys like SDSS. Modern observational cosmology demonstrate that actually detected sizes of large scale structures acheaving 1000 Mpc:
Baryshev, Yurij; Teerikorpi, Pekka
"Fundamental Questions of Practical Cosmology ",
Astrophysics and Space Science Library, Volume 383
ISBN 978-94-007-2378-8. Springer Science+Business Media B.V., 2012
http://www.springerlink.com/content/n64585/?MUD=MP
So the construction of true cosmological model is an open problem.
I am not an expert of this field but I though I heard that models of inhomogeneities like most LTB were killed by the SZ effect for clusters.
ResponderEliminarIt's a very interesting question, as there are rather few ways to probe the interior of the past light cone at the same cosmic time, to do a real test. We are currently using the fossil record of galaxies at different distances to probe their past world lines, and this allows us to test to what extent the average star formation rate is homogeneous. This is not a full test, of course - to do that would require demonstration that the metric was Friedmann-Robertson-Walker, and that has not been done. We should have some results soon. As Steve says, observations of the CMB and large scale structure are consistent with homogeneity (give or take fluctuations) but strictly they are on the past light cone, so are more a test of isotropy.
ResponderEliminar