A new Cepheid distance to the maser-host galaxy NGC 4258 and its implications for the Hubble Constant

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dc.creatorMacri, L. M.
dc.creatorStanek, K. Z.
dc.creatorBersier, D.
dc.creatorGreenhill, L.
dc.creatorReid, M.
dc.date2006-08-10
dc.date2006-08-10
dc.date.accessioned2026-07-07T10:23:25Z
dc.date.available2026-07-07T10:23:25Z
dc.descriptionWe present initial results from a time-series BVI survey of two fields in NGC 4258 using the Advanced Camera for Surveys onboard the Hubble Space Telescope. This galaxy was selected because of its accurate maser-based distance, which is anticipated to have a total uncertainty of ~3%. The goal of the HST observations is to provide an absolute calibration of the Cepheid Distance Scale and to measure its dependence on chemical abundance (the so-called "metallicity effect"). We carried out observations of two fields at different galactocentric distances with a mean abundance difference of 0.5 dex. We discovered a total of 281 Cepheids with periods ranging from 4 to 45 days (the duration of our observing window). We determine a Cepheid distance modulus for NGC 4258 (relative to the LMC) of 10.88 +- 0.04 (random) +- 0.05 (systematic) mag. Given the published maser distance to the galaxy, this implies μ(LMC)=18.41 +- 0.10 (r) +- 0.13 (s) mag or D(LMC)= 48.1 +- 2.3 (r) +- 2.9 (s) kpc. We measure a metallicity effect of γ=-0.29 +- 0.09 (r) +- 0.05 (s) mag/dex. We see no evidence for a variation in the slope of the Period-Luminosity relation as a function of abundance. We estimate a Hubble Constant of H_0= 74 +- 3 (r) +- 6 (s) km/s Mpc using a recent sample of 4 well-observed type Ia SNe and our new calibration of the Cepheid Distance Scale. It may soon be possible to measure the value of H_0 with a total uncertainty of 5%, with consequent improvement in the determination of the equation of state of dark energy.
dc.description39 pages, 24 figures. Accepted for publication in the Astrophysical Journal. Full-resolution version available in PS and PDF formats at http://www.noao.edu/staff/lmacri/0608211-full.ps.gz and http://www.noao.edu/staff/lmacri/0608211-full.pdf
dc.identifierhttps://arxiv.org/abs/astro-ph/0608211
dc.identifierhttp://arxiv.org/abs/astro-ph/0608211
dc.identifierAstrophys.J.652:1133-1149,2006
dc.identifierdoi:10.1086/508530
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/175821
dc.subjectAstrophysics
dc.titleA new Cepheid distance to the maser-host galaxy NGC 4258 and its implications for the Hubble Constant
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