科研之友
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摘要
We use gravitational lenses from the Cosmic Lens All-Sky Survey to constrain the evolution of galaxies since redshift z similar to 1 in the current Lambda cold dark matter cosmology. This constraint is unique as it is based on a mass-selected lens sample of galaxies. Our method of statistical analysis is the same as that done in recent work by K.-H. Chae. We parameterize the early-type number density evolution in the form of (1 + z)(nun) and the velocity dispersion in the form of (1 + z)(nuupsilon). We find that nu(n) = -0.11(-0.4)(+0.82) (1 sigma) if we assume <LF>nu(upsilon) = 0, implying that the number density of early-type galaxies is within 50%-<LF>164% of the present-day value at redshift z = 1. Allowing the velocity dispersion to evolve, we find that nu(upsilon) = 0.4(-0.4)(+0.5) (1 sigma), indicating that the velocity dispersion must be within 57%-107% of the present-day value at z = <LF>1. These results are consistent with the early formation and passive evolution of early-type galaxies. More stringent limits from lensing can be obtained from future large lens surveys and by using very high redshift quasars (z greater than or similar to 5) such as those found from the Sloan Digital Sky Survey.
- 出版日期2003-12-20
