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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.
We report on the current status of our search for protoclusters around quasars at z > 4. While the search is still very incomplete, clustered companion galaxies are found in virtually every case examined so far. The implied comoving number densities
At intermediate and high redshifts, measurements of galaxy star-formation rates are usually based on rest-frame ultraviolet (UV) data. A correction for dust attenuation, A_UV, is needed for these measurements. This correction is typically inferred fr
Some recent work in nuclear beta decay related to the value of |Vud| is described along with some near-term goals for future measurements.
A recent Penning-trap measurement of the masses of 46V and 46Ti leads to a Qec value that disagrees significantly with the previously accepted value, and destroys overall consistency among the nine most precisely characterized T=1 superallowed beta e
We summarize observations of the properties of powerful radio galaxies and their environments from z = 0 to 5. These data show that some high redshift radio galaxies inhabit regions of gas and galaxy over-densities indicative of proto-cluster environments.