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CONSTRAINTS ON A-DECAYING COSMOLOGY FROM OBSERVATIONAL POINT OF VIEW

  • KOMIYA ZEN (Department of Physics, College of Science, Tokyo University of Science) ;
  • KAWABATA KIYOSHI (Department of Physics, College of Science, Tokyo University of Science) ;
  • HIRANO KOICHI (Department of Physics, College of Science, Tokyo University of Science) ;
  • BUNYA HIROSHI (Department of Physics, College of Science, Tokyo University of Science) ;
  • YAMAMOTO NAOTAKA (Grid Technology Research Center, National Institute of Advanced Industrial Science and Technology)
  • Published : 2005.06.01

Abstract

To constrain the values of the model parameters for the cosmological models involving the time-decaying $\Lambda$ term, we have computed sets of theoretical predictions for the N-m relation of galaxies as well as the CMB angular power spectrum: three types of variation, viz., ${\Lambda}{\propto} T^{-1},\;a^{-m}$, and $H^n$ are thereby assumed following Overduin & Cooperstock (1998), although we concentrate here on the discussion of the results obtained from the first type. Our results for the N-m relation indicate that the observed excess of the galaxy counts N in the faint region beyond the blue apparent magnitude 24 can be reasonably well accounted for with the value of ${\iota}$ in the range between 0.2 and 1. Furthermore, a comparison of our computational results of the CMB spectra with the observational data shows that the models with a mild degree of the $\Lambda$ term decay, viz., with the value of ${\iota}{\le}$0.4, are favorable. In this case, the age of our universe turns out to be larger than or equal to 14 Gyr, the lower limit inferred from some Uranium datings.

Keywords

cosmology;cosmological term;time variation;galaxy number counts;galaxy merger;CMB spectra

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