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A Cepheid distance to the Fornax cluster and the local expansion rate of the Universe

Madore, Barry F. and Freedman, Wendy L. and Silbermann, N. and Harding, Paul and Huchra, John and Mould, Jeremy R. and Graham, John A. and Ferrarese, Laura and Gibson, Brad K. and Han, Mingsheng and Hoessel, John G. and Hughes, Shaun M. and Illingworth, Garth D. and Phelps, Randy and Sakai, Shoko and Stetson, Peter (1998) A Cepheid distance to the Fornax cluster and the local expansion rate of the Universe. Nature, 395 (6697). pp. 47-50. ISSN 0028-0836.

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Both galaxy distances and velocities are required for the determination of the expansion rate of the Universe, as described by the Hubble constant H_0. The radial velocities of galaxies arise not just from this expansion but also from random components and large-scale flows. To reach out to distances dominated by the overall cosmic expansion, it is necessary to probe large physical scales where galaxy–galaxy and galaxy–cluster interactions become less important. But accurate distances of nearby galaxies and clusters (commonly measured using Cepheid variable stars) are nevertheless required to calibrate the indirect distance indicators generally used to measure these large scales. Here we report a Cepheid distance of 18.6 ± 1.9 (statistical error) for the galaxy NGC1365 in Fornax, a cluster of galaxies in the Southern Hemisphere. We find a value of H_0 = 70 km s^(-1) Mpc^(-1) from Fornax alone, and 73 km s^(-1) Mpc^(-1) from the intervening galaxy flow, each corrected for infall into the Virgo cluster. These values are consistent with the Hubble constant measured in the far field using secondary methods. Our data support previous suggestions that the local small-scale velocity field has very small scatter (~ ± 70 km s^(-1)).

Item Type:Article
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URLURL TypeDescription ReadCube access
Madore, Barry F.0000-0002-1576-1676
Freedman, Wendy L.0000-0003-3431-9135
Mould, Jeremy R.0000-0003-3820-1740
Illingworth, Garth D.0000-0002-6668-2011
Sakai, Shoko0000-0001-5972-663X
Stetson, Peter0000-0001-6074-6830
Additional Information:© 1998 Macmillan Publishers Ltd. Received 18 March; accepted 1 June 1998. This work was supported by NASA and the NSF, and made extensive use of the NASA/IPAC Extragalactic Database (NED). Observations are based on data obtained using the Hubble Space Telescope which is operated by the Space Telescope Science Institute under contract from the Association of Universities for Research in Astronomy. L.F. acknowledges support by NASA through a Hubble Fellowship grant awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA.
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Issue or Number:6697
Record Number:CaltechAUTHORS:20150624-113031846
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Official Citation:A Cepheid distance to the Fornax cluster and the local expansion rate of the Universe p47 Barry F. Madore, Wendy L. Freedman, N. Silbermann, Paul Harding, John Huchra, Jeremy R. Mould, John A. Graham, Laura Ferrarese, Brad K. Gibson, Mingsheng Han, John G. Hoessel, Shaun M. Hughes, Garth D. Illingworth, Randy Phelps, Shoko Sakai and Peter Stetson doi:10.1038/25678
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58584
Deposited By: Ruth Sustaita
Deposited On:24 Jun 2015 19:01
Last Modified:17 Nov 2019 07:30

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