THE EXTRAGALACTIC DISTANCE SCALE KEY PROJECT XXVII.
THE FUNDAMENTAL PLANE AND D_n-sigma RELATIONS
IN LEO I, VIRGO, AND FORNAX AND A
DERIVATION OF THE HUBBLE CONSTANT

DANIEL D KELSON, GARTH D. ILLINGWORTH, JOHN L. TONRY,
WENDY L. FREEDMAN, ROBERT C. KENNICUTT, JR., JEREMY R. MOULD,
JOHN A. GRAHAM, JOHN P. HUCHRA, LUCAS M. MACRI, BARRY F. MADORE,
LAURA FERRARESE, BRAD K. GIBSON, ABHIJIT SAHA, SHOKO SAKAI,
PETER B. STETSON, EDWARD A. AJHAR, JOHN P. BLAKESLEE, ALAN DRESSLER,
HOLLAND C. FORD, SHAUN M.G. HUGHES, KIM M. SEBO, AND NANCY A. SILBERMANN

ABSTRACT

Using published photometry and spectroscopy, we construct the fundamental plane and D_n-sigma relations in Leo I, Virgo and Fornax. The published Cepheid P-L relations to spirals in these clusters fixes the relation between angular size and metric distance in both the fundamental plane and D_n-sigma relations. Using the locally calibrated fundamental plane, we infer distances to a sample of clusters with a mean redshift of cz approx 6000 km s^-1, and derive H₀ = 78 + 7 + 8 km s^-l Mpc^-l (random, systematic). This value includes a downward correction of 5% + 5% for depth effects in the Cepheid distances to the nearby clusters. If one further adopts the Key Project's metallicity correction to the Cepheid PL relation, the value of the Hubble constant decreases by a further 6% + 4%. We find that the value obtained using either the CMB, or a flow-field model, for the reference frame of the distant clusters, agree to within 1%. The D_n-sigma relation also produces similar results, as expected from the correlated nature of the two scaling relations. A complete discussion of the sources of random and systematic error in this determination of the Hubble constant is also given, in order to facilitate comparison with the other secondary indicators being used by the Key Project.

Colorado Astrophysics Preprint #396
to appear in Astrophysical Journal