AAS 197, January 2001
Session 95. Cosmological Parameters and Evolution
Oral, Wednesday, January 10, 2001, 1:30-3:00pm, Town and Country

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[95.03] Redshift-Volume Test of Cosmological Parameters Using Distant Early-Type Galaxies: Further Evidence for Dark Energy in The Universe

M. Im (UCSC)

We report a new measurement of the cosmological parameters using distant early-type galaxies compiled from two major distant galaxy surveys --- the Deep Extragalactic Evolutionary Probe (http://www.ucolick.org/simdeep) and the HST Medium Deep Survey (http://astro.phys.cmu.edu/mds/index.html). Due to curvature effects, an open or \Lambda-dominated universe provides more volume for a given area on the sky than a flat or closed universe. The ``redshift-volume'' test uses the volume change as a function of redshift to measure cosmological parameters, and it has been considered as a potentially very powerful way to determine the geometry of the universe --- more powerful than the recent cosmological tests with Type-Ia Supernovae.

We have identified distant early-type galaxies whose evolutionary changes are well-understood, and counted their number as a function of redshift to measure the volume of the universe out to z=1. Our results from this redshift-volume test agree with previous measurements of cosmological parameters, providing yet further evidence that the universe is dominated by the dark energy, and that the mass density of the universe is too low to stop the expansion of the universe. This work is supported by STScI grant AR-87670.4-A and NSF grant AST-9529098.

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The author(s) of this abstract have provided an email address for comments about the abstract: myung@ucolick.org

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