A comparison of the correlation lengths on red galaxies with blue can provide a new cosmic ruler. Clustering of old, red galaxies reflects the density fluctuations in the early universe. Assuming the length scales associated with this clustering are constant everywhere and evolve slowly with time, the average size or correlation length of the clusters can be calibrated against local galaxies and used as a cosmic ruler. Longo finds that the correlation length averaged over many clusters is nearly constant and can be measured to ~2% out to z ~ 0.5 (http://au.arxiv.org/obs/0810.4066).
Thursday, 23 October 2008
New cosmic ruler
A comparison of the correlation lengths on red galaxies with blue can provide a new cosmic ruler. Clustering of old, red galaxies reflects the density fluctuations in the early universe. Assuming the length scales associated with this clustering are constant everywhere and evolve slowly with time, the average size or correlation length of the clusters can be calibrated against local galaxies and used as a cosmic ruler. Longo finds that the correlation length averaged over many clusters is nearly constant and can be measured to ~2% out to z ~ 0.5 (http://au.arxiv.org/obs/0810.4066).
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment