The Ups and Downs of the Hubble Constant

Tammann, G.

doi:10.1002/9783527619030.ch1

Cited by 8 publications

(5 citation statements)

References 129 publications

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“…Individual LMC moduli are compiled in Federspiel et ai (1998) and give (m -M) = 18.54 ± 0.03. This value is also in good agreement with the position of the red-giant tip (Lee et α/., 1993;Tammann, 1996). Conservatively (m -M) = 18.50 has been adopted in the following.…”

Section: The Calibration Of Hsupporting

confidence: 70%

The Linearity of the Cosmic Expansion Field and the Value of the Hubble Constant

Tammann¹

1999

Symp. - Int. Astron. Union

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Abstract. A linearity test shows Ho to decrease by 7% out to 18 000 km s"1 . The value at 10 000 kms" 1 is a good approximation to the mean value of Ho over very large scales. The construction of the extragalactic distance scale is discussed. Field galaxies, cluster distances relative to Virgo, and blue supernovae of type la yield Ho (cosmic) with increasing weight; they give consistently Ho = 57 ± 7 (external error). This value is supported by purely physical distance determinations (SZ effect, gravitational lenses, MWB fluctuations). Arguments for Ho > 70 are discussed and shown to be flawed.

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Section: The Calibration Of Hsupporting

confidence: 70%

The Linearity of the Cosmic Expansion Field and the Value of the Hubble Constant

Tammann¹

1999

Symp. - Int. Astron. Union

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“…It is not an attempt to review the global history of H 0 determinations, as this has been done many times, often by the original protagonists or their close collaborators. For an overall review of this process see, for example, [223] and [210]. Compilations of data and analysis of them are given by Huchra (http://cfa-www.harvard.edu/∼huchra/hubble), and Gott ([77], updated by [35]) 5.…”

Section: Introductionmentioning

confidence: 99%

The Hubble Constant

Jackson

2015

Living Rev Relativ

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I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of their distance by geometric means. The second category comprises the use of all-sky cosmic microwave background, or correlations between large samples of galaxies, to determine information about the geometry of the Universe and hence the Hubble constant, typically in a combination with other cosmological parameters. Many, but not all, object-based measurements give H0 values of around 72–74 km s−1 Mpc−1, with typical errors of 2–3 km s−1 Mpc−1. This is in mild discrepancy with CMB-based measurements, in particular those from the Planck satellite, which give values of 67–68 km s−1 Mpc−1 and typical errors of 1–2 km s−1 Mpc−1. The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant. Whether a discrepancy exists, and whether new physics is needed to resolve it, depends on details of the systematics of the object-based methods, and also on the assumptions about other cosmological parameters and which datasets are combined in the case of the all-sky methods.

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“…It is not an attempt to review the global history of H 0 determinations, as this has been done many times, often by the original protagonists or their close collaborators. For an overall review of this process see, for example, [161] and [149]; see also data compilations and reviews by Huchra (http://cfa-www.harvard.edu/∼huchra/hubble) and Allen (http://www.institute-of-brilliant-failures.com/). …”

Section: Introductionmentioning

confidence: 99%

The Hubble Constant

Jackson

2007

Living Rev. Relativ.

114

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I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. In the last 20 years, much progress has been made and estimates now range between 60 and 75 km s−1 Mpc−1, with most now between 70 and 75 km s−1 Mpc−1, a huge improvement over the factor-of-2 uncertainty which used to prevail. Further improvements which gave a generally agreed margin of error of a few percent rather than the current 10% would be vital input to much other interesting cosmology. There are several programmes which are likely to lead us to this point in the next 10 years.

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The Ups and Downs of the Hubble Constant

Cited by 8 publications

References 129 publications

The Linearity of the Cosmic Expansion Field and the Value of the Hubble Constant

The Linearity of the Cosmic Expansion Field and the Value of the Hubble Constant

The Hubble Constant

The Hubble Constant

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