04/24/2012:
A 2005 paper
Eisenstein gives a relatively straightforward explanation of baryonic acoustics once one makes the mental gear change from thinking in observational astronomy space to redshift space. My eyebrows went up at the statement, “It does rely on the well-understood linear perturbation theory of the recombination epoch to relate the perturbations in the photons . . . we have measured the relative distance between two radically different redshifts using a purely geometric method and the same physical mechanism” because the evidence set forth in the discussion didn’t seem to support a purely linear perturbation. I wondered whether supersonic shock behavior manifest itself in measureable turbulence. Correct me if I‘m wrong, but is the answer found in this point from the same paper: “the beat frequency between the peaks and troughs of the acoustic oscillations is a very small wavenumber that is well inside the linear regime.”
Eisenstein’s
2006 paper addressed the Swinburne “galaxies operate in pairs 490 million ly apart” point this way: “We argue that the dominant non-linear effect is the differential motion of pairs of tracers separated by 150 Mpc. These motions are driven by bulk flows and cluster formation and are much smaller than the acoustic scale itself.” Other useful papers are:
Percival et al., and what is perhaps the last (or anyway latest) word on the subject, the 29 Mar 2012
Beth Reid et al. paper. The arXiv list of Eisenstein’s
papers is also worth a look. It’s heartening how many people are active in this field.
=Dana