Nereid said:
turbo-1: do you have a reference to 'the apparent surplus of high-redshift quasars'?
For the avoidance of doubt, I agree that these early studies of the early universe have produced fascinating results, which MAY end up being shown to be inconsistent with the concordance model, but it's early days (did I say that already?)
As recently as 10 years ago, researchers (including Hewitt, Foltz and Chaffee 1993) had concluded that the epoch of quasar formation was at z~3. Now, with better instruments, more sophisticated identifying techniques, and deeper surveys, discovery of very faint quasars with extreme redshifts yielding z~6 is no longer big news. Here is an example of how more sophisticated identification techniques can cause an explosion in the numbers of known high-redshift quasars.
http://scholar.google.com/url?q=http://www.edpsciences.org/articles/aa/pdf/press-releases/PRAA200404.pdf
Standard cosmology is still loaded with assumptions that were not too problematic in the light of z~3 quasars, but may be quite untenable with the identification of multiple z~6 quasars. When the Large Binocular Telescope comes on line, I predict that z~6 quasars will be left in the dust. There is a high-spirited race on to discover the oldest most distant objects, and the LBT is going to be irresistable to those researchers obsessed with high redshift objects.
As an example of the problems that the Big Bang has with high-z objects: X Fan, VK Narayanan, RH Lupton, MA Strauss, et al, in this paper studied three z~6 quasars - seen as they would have been about 800 million years after the big bang,
if their redshifts are cosmological in origin. They calculate that the black hole cores of these quasars each has several billion solar masses.
Assuming that SDSS 1044-0125 is radiating at the Eddington luminosity, this object contains a central black hole of several billion solar masses. The assembly of such massive objects in a timescale shorter than 1 Gyr yields constraints on models of the formation of massive black holes (see, e.g., Haiman & Loeb 2001).
The authors also estimate that the broad emission line regions surrounding these quasars have super-solar metallicity. The paper is at this link:
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001AJ...122.2833F&db_key=AST
Now, how did black holes with masses equivalent to several billion suns have time to form in less a billion years after the big bang? And how do we explain the metallicity of their environments so early in the life of the universe? How could enough massive stars have developed and gone supernovae in that 800 million years to provide metallicity of those environments equal to or greater that of our own, which has been metal-enrichened by billions of years worth of supernovae?
If quasars are the products of local ejection events, and have intrinsic redshifts that moderate as they evolve, these problems go away. If quasars are at the distances (and look-back times) suggested by their redshifts, these z~6 objects already place severe constraints on star formation and the development of structure in the infancy of the BB universe. Objects of greater redshift are likely to be found, and will strain the standard model even further.