C.D.S. - SIMBAD4 rel 1.7 - 2020.07.03CEST21:43:09

2017A&A...598A.111R - Astronomy and Astrophysics, volume 598A, 111-111 (2017/2-1)

The background Friedmannian Hubble constant in relativistic inhomogeneous cosmology and the age of the Universe.


Abstract (from CDS):

Context. In relativistic inhomogeneous cosmology, structure formation couples to average cosmological expansion. A conservative approach to modelling this assumes an Einstein-de Sitter model (EdS) at early times and extrapolates this forward in cosmological time as a "background model" against which average properties of today's Universe can be measured.
Aims. This modelling requires adopting an early-epoch-normalised background Hubble constant Hbg1.
Methods. Here, we show that the ΛCDM model can be used as an observational proxy to estimate Hbg1 rather than choose it arbitrarily. We assume (i) an EdS model at early times; (ii) a zero dark energy parameter; (iii) bi-domain scalar averaging-division of the spatial sections into over- and underdense regions; and (iv) virialisation (stable clustering) of collapsed regions.
Results. We find Hbg1=37.7±0.4km/s/Mpc (random error only) based on a Planck ΛCDM observational proxy.
Conclusions. Moreover, since the scalar-averaged expansion rate is expected to exceed the (extrapolated) background expansion rate, the expected age of the Universe should be much younger than 2/(3Hbg1)=17.3Gyr. The maximum stellar age of Galactic bulge microlensed low-mass stars (most likely: 14.7Gyr; 68% confidence: 14.0-15.0Gyr) suggests an age of about a Gyr older than the (no-backreaction) ΛCDM estimate.

Abstract Copyright: © ESO, 2017

Journal keyword(s): cosmology: observations - cosmological parameters - distance scale - large-scale structure of Universe - dark energy

Simbad objects: 2

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Number of rows : 2

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
1 HD 140283 Pe* 15 43 03.0967798658 -10 56 00.595803430 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 852 0
2 NAME Galactic Bulge reg ~ ~           ~ 3387 0

    Equat.    Gal    SGal    Ecl

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