CARNEGIE HUBBLE PROGRAM: A MID-INFRARED CALIBRATION OF THE HUBBLE CONSTANT

• Published in: The Astrophysical journal Vol. 758; no. 1; pp. 1 - 10
• Main Authors: FREEDMAN, Wendy L, MADORE, Barry F, SCOWCROFT, Victoria, BURNS, Chris, MONSON, Andy, PERSSON, S. Eric, SEIBERT, Mark, RIGBY, Jane
• Format: Journal Article
• Language: English
• Published: Bristol IOP 10-10-2012
• Subjects: Acoustics; ANISOTROPY; ASTRONOMY; ASTROPHYSICS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BARYONS; Calibration; CEPHEIDS; COSMOLOGY; Earth, ocean, space; EQUATIONS OF STATE; Exact sciences and technology; Hubble constant; Hubble Space Telescope; LUMINOSITY; MAGELLANIC CLOUDS; MILKY WAY; NEUTRINOS; NONLUMINOUS MATTER; OSCILLATIONS; RED SHIFT; RELATIVISTIC RANGE; RELICT RADIATION; SUPERNOVAE; TELESCOPES; UNIVERSE; Red shift; Uncertainty; Galaxies; Cosmic background radiation; Spatial observatory; Period luminosity relation; Type I supernova; Neutrinos; Dark energy; cosmological parameters; Flat metric; Cepheids; Distance scale; Milky Way; stars: variables: Cepheids; Baryons; Equations of state; Cosmological parameter; Anisotropy; Metallicity; galaxies: distances and redshifts; Elementary particles; Hubble constant; Cosmology; cosmology: observations; Massless particles; Large Magellanic Cloud
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637x/758/1/24

Using a mid-infrared calibration of the Cepheid distance scale based on recent observations at 3.6 mu m with the Spitzer Space Telescope, we have obtained a new, high-accuracy calibration of the Hubble constant. In combination with the new Spitzer calibration, the systematic uncertainty in H[sub 0] over that obtained by the Hubble Space Telescope Key Project has decreased by over a factor of three. The result, in combination with WMAP7 measurements of the cosmic microwave background anisotropies and assuming a flat universe, yields a value of the equation of state for dark energy, w[sub 0] = -1.09 [+ or -] 0.10. Alternatively, relaxing the constraints on flatness and the numbers of relativistic species, and combining our results with those of WMAP7, Type Ia supernovae and baryon acoustic oscillations yield w[sub 0] = -1.08 [+ or -] 0.10 and a value of N[subeff] = 4.13 [+ or -] 0.67, mildly consistent with the existence of a fourth neutrino species.