Distance Measurement of Galaxies to a Redshift of ∼ 0.1 Using the CO-Line Tully-Fisher Relation

We report on the first results of a long-term project to derive distances ofgalaxies at cosmological distances by applying the CO-line width-luminosityrelation. We have obtained deep CO-line observations of galaxies at redshiftsup to 29,000 km/s using the Nobeyama 45-m mm-wave Telescope, and somesupplementary data were obtained by using the IRAM 30-m telescope. We havedetected the CO line emission for several galaxies, and used their CO linewidths to estimate the absolute luminosities using the line-width-luminosityrelation. In order to obtain photometric data and inclination correction, wealso performed optical imaging observations of the CO-detected galaxies usingthe CFHT 3.6-m telescope at high resolution. The radio and optical data havebeen combined to derive the distance moduli and distances of the galaxies, andHubble ratios were estimated for these galaxies. We propose that the CO linewidth-luminosity relation can be a powerful method to derive distances ofgalaxies to redfhift of z = 0.1 and to derive the Hubble ratio in a significantvolume of the universe. Key words: Cosmology - Galaxies: general - Distance scale - CO lineComment: To appear in PASJ, Plain Tex, 3 figures (in 10 ps files