Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-08-19
Astrophys.J.549:688-701,2001
Astronomy and Astrophysics
Astrophysics
26 pages including 9 eps figures. Submitted to ApJ
Scientific paper
10.1086/319462
Measurements of the cosmological density parameter Omega using techniques that exploit the gravity-induced motions of galaxies constrain, in linear perturbation theory, the degenerate parameter combination beta = Omega^{0.6}/b, where the linear bias parameter b is the ratio of the fluctuation amplitudes of the galaxy and mass distributions. However, the relation between the galaxy and mass density fields depends on the complex physics of galaxy formation, and it can in general be non-linear, stochastic, and perhaps non-local. The one-parameter linear bias model is almost certainly oversimplified, which leads to the obvious question: What is the quantity beta that is actually measured by different techniques? To address this question, we estimate beta from galaxy distributions that are constructed by applying a variety of locally biased galaxy formation models to cosmological N-body simulations. We compare the values of beta estimated using three different techniques: a density-density comparison similar to the POTENT analysis, a velocity-velocity comparison similar to the VELMOD analysis, and an anisotropy analysis of the redshift-space power spectrum. In most cases, we find that beta estimated using all three methods is similar to the asymptotic value of Omega^{0.6}/b_{sigma}(R) at large R, where b_{sigma}(R) is the ratio of rms galaxy fluctuations to rms mass fluctuations on scale R. Thus, something close to the conventional interpretation of beta continues to hold even for complex bias models. Moreover, we find that beta estimates made using these three methods should, in principle, agree with each other. It is thus unlikely that non-linear or scale-dependent bias is responsible for the discrepancies that exist among current measurements of beta from different techniques.
Berlind Andreas A.
Narayanan Vijay K.
Weinberg David H.
No associations
LandOfFree
Biased Galaxy Formation And Measurements Of Beta does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Biased Galaxy Formation And Measurements Of Beta, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Biased Galaxy Formation And Measurements Of Beta will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-125579