Allan Sandage and the Cosmic Expansion

Abstract

This is an account of Allan Sandage's work on (1) The character of the expansion field. For many years he has been the strongest defender of an expanding Universe. He later explained the CMB dipole by a local velocity of 220 +/- 50 km/s toward the Virgo cluster and by a bulk motion of the Local supercluster (extending out to ~3500 km/s) of 450-500 km/s toward an apex at l=275, b=12. Allowing for these streaming velocities he found linear expansion to hold down to local scales (~300 km/s). (2) The calibration of the Hubble constant. Probing different methods he finally adopted - from Cepheid-calibrated SNe Ia and from independent RR Lyr-calibrated TRGBs - H_0 = 62.3 +/- 1.3 +/- 5.0 km/s/Mpc.

12 pages, 11 figures, 1 table, Submitted to Astrophysics and Space Science, Special Issue on the Fundamental Cosmic Distance Scale in the Gaia Era

References in corpus (13)

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• Improved Distances to Type Ia Supernovae with Multicolor Light Curve Shapes: MLCS2k2
• The Hubble Constant: A Summary of the HST Program for the Luminosity Calibration of Type Ia Supernovae by Means of Cepheids
• A new Cepheid distance to the maser-host galaxy NGC 4258 and its implications for the Hubble Constant
• Cepheid Parallaxes and the Hubble Constant
• Cepheid Distances to SNe Ia Host Galaxies based on a Revised Photometric Zero-Point of the HST-WFPC2 and New P-L Relations and Metallicity Corrections
• Planetary Nebulae in Face-On Spiral Galaxies. I. Planetary Nebula Photometry and Distances
• Cepheid Calibrations of Modern Type Ia Supernovae:Implications for the Hubble Constant
• Comparison of Distances from RR Lyrae Stars, the Tip of the Red-Giant Branch and Classical Cepheids
• Cepheids in external galaxies. I. The maser-host galaxy NGC 4258 and the metallicity dependence of P-L and P-W relations
• The expansion field: The value of H_0
• Calibrating Type Ia Supernovae using the Planetary Nebula Luminosity Function I. Initial Results
• Temperature Differences in the Cepheid Instability Strip Require Differences in the Period-Luminosity Relation in Slope and Zero Point

Cited by in corpus (6)

• Cepheid theoretical models and observations in HST/WFC3 filters: the effect on the Hubble constant Ho
• The luminosity of supernovae of type Ia from TRGB distances and the value of H_0
• Theoretical fit of Cepheid light an radial velocity curves in the Large Magellanic Cloud cluster NGC 1866
• Distance and reddening of the Local Group dwarf irregular galaxy NGC 6822
• On the Form of the Spitzer Leavitt Law and its Dependence on Metallicity
• The bulk flow motion and the Hubble-Lema\^ıtre law in the Local Universe with the ALFALFA survey