In the first million years of the Universe, cosmic perturbations drive sound waves into the cosmic plasma. These sound waves are seen in the cosmic microwave background maps as the acoustic oscillations. We have now detected the imprint of the acoustic phenomenon in the clustering of nearby galaxies, thereby completing an important test of our theory of gravitational structure formation. Moreover, because the sound wave pattern has been seen both at low redshift in the galaxies and at high redshift in the CMB, we can measure the relative distance to these two very disparate redshifts. This yields a geometric demonstration of the acceleration of the expansion rate of the universe.

Here are a bunch of relevant links.

• The paper itself (submitted to the Astrophysical Journal) (astro-ph) (PDF) (PS)

• The SDSS press release.

• The 2dF survey has a similar result; here's a link to their page.

• A non-technical description of what we've found. (PDF) (PS)

• Some illustrative (i.e., not realistic) animations of expanding waves: One wave (the color change is supposed to represent the transition from ionized to neutral gas) and Many superposed waves (to show that one doesn't actually get a bullseye pattern in the sky). [apologies, but these gif files still have a minor flaw in the transparency setting that I haven't fixed yet.]

• Some figures, including the press figure and pie diagrams. Credit: Sloan Digital Sky Survey.

• An illustrated technical explanation of the acoustic phenomenon.

• Another description, this time a bit more technical yet. (PDF) (PS)

• Our poster from the January 2005 AAS meeting. (PDF)

• The main SDSS web page and our third data release, which contains our on-line documentation of the survey.

• The NYU value-added galaxy catalog, which contains the large-scale structure samples. Or see the Blanton et al. (2004) paper.

• Electronic copies of our correlation function and its covariance matrix

• Description of the recipe we use to generate predicted correlation functions from a given cosmological theory

• Electronic copies of the figures in the paper. Credit: Eisenstein et al. (2005)

• Links to papers that document aspects of the LRG sample: Eisenstein et al. (2001), Zehavi et al (2004), Hogg et al (2004), and of course the SDSS data release.

• A code to forecast the acoustic scale precision available from future redshift surveys is here.