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Quintessence Cosmology and Varying
Takeshi Chiba, Kazunori Kohri
If the reported measurements of the time variation of the fine structure constant from observations of distant QSOs are correct, combined with the Oklo limit they would strongly co…
Constancy of the Constants of Nature
Takeshi Chiba
The current observational and experimental bounds on time variation of the constants of Nature are briefly reviewed.
Extended Quintessence and its Late-time Domination
Takeshi Chiba
Various astronomical observations point towards the evidence for dark energy. One of the most mysterious problem is the coincidence problem: why dark energy becomes dominant only r…
Lens Model Degeneracy and Cosmological Tests by Strong Gravitational Lensing
Takeshi Chiba, Ryuichi Takahashi
We estimate the sensitivity of lensing observables to the parameters in the lens model (isothermal sphere/Navarro-Frenk-White profile) parameters and to cosmological parameters. We…
Gravitational Lens Statistics and The Density Profile of Dark Halos
Ryuichi Takahashi, Takeshi Chiba
We investigate the influence of the inner profile of lens objects on gravitational lens statistics taking into account of the effect of magnification bias and both the evolution an…