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Subaru Spectroscopy of the Gravitational Lens HST 14176+5226: Implications for a Large Cosmological Constan

Youichi Ohyama·Takashi Hamana·Nobunari Kashikawa·Masashi Chiba·Toshifumi Futamase·Masanori Iye·Koji S. Kawabata·Kentaro Aoki·Toshiyuki Sasaki·George Kosugi·Tadafumi Takata
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Abstract

We present new optical spectroscopy of the lens elliptical galax in the ``Einstein Cross'' lens system HST 14176+5226, using the Faint Object Camera and Spectrograph (FOCAS) of the Subaru t Our spectroscopic observations are aimed at measuring the stella dispersion of the lens galaxy, located at high redshift of z_L= as an important component to lens models. We have measured this 230 +- 14 km s^{-1} (1 sigma) inside 0.35 effective radi based on the comparison between the observed galaxy spectrum and templates of three G-K giants by means of the Fourier cross-corr To extract the significance of this information on the geometry universe which also affects the lensing of the background image, to fit three different lens models to the available data of the Provided that the lens galaxy has the structural and dynamical p (i.e., its radial density profile, core radius, and velocity ani similar to those of local elliptical galaxies, we calculate the function for the simultaneous reproduction of both the observed and newly measured velocity dispersion of the lens. Although the interval depends rather sensitively on the adopted lens models o parameters, our experiments suggest the larger likelihood for a cosmological constant, Omega_Lambda: formal 1 sigma lower Omega_Lambda in the flat universe ranges 0.73 to 0.97, where lower limit is basically unavailable. This method for determinin model is thus dependent on lens models but is insensitive to oth ambiguities, such as the dust absorption or the evolutionary eff galaxies. Exploring spectroscopic observations of more lens gala redshift may minimize the model uncertainties and thus place a m constraint on Omega_Lambda.

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Youichi Ohyama, Takashi Hamana, Nobunari Kashikawa, Masashi Chiba, Toshifumi Futamase, Masanori Iye, Koji S. Kawabata, Kentaro Aoki, Toshiyuki Sasaki, George Kosugi, Tadafumi Takata. 2002-03-19. Subaru Spectroscopy of the Gravitational Lens HST 14176+5226: Implications for a Large Cosmological Constan. https://doi.org/10.1086/340565

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