Impact of a Locally Measured H-0 on the Interpretation of Cosmic-chronometer Data
AffiliationUniv Arizona, Dept Phys, Program Appl Math
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PublisherIOP PUBLISHING LTD
CitationImpact of a Locally Measured H-0 on the Interpretation of Cosmic-chronometer Data 2017, 835 (2):270 The Astrophysical Journal
JournalThe Astrophysical Journal
Rights© 2017. The American Astronomical Society. All rights reserved.
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AbstractMany measurements in cosmology depend on the use of integrated distances or time, but. galaxies evolving passively on a timescale much longer than their age difference allow us to determine the expansion rate H(z) solely as a function of the redshift-time derivative dz/dt. These model-independent "cosmic chronometers" can therefore be powerful discriminators for testing different cosmologies. In previous applications, the available sources strongly disfavored models (such as Lambda CDM) predicting a variable acceleration, preferring instead a steady expansion rate over the redshift range 0 less than or similar to z less than or similar to 2. A more recent catalog of 30 objects appears to suggest non-steady expansion. In this paper, we show that such a result is entirely due to the inclusion of a high, locally inferred value of the Hubble constant H-0 as an additional datum in a set of otherwise pure cosmic-chronometer measurements. This H-0, however, is not the same as the background Hubble constant if the local expansion rate is influenced by a Hubble Bubble. Used on their own, the cosmic chronometers completely reverse this conclusion, favoring instead a constant expansion rate out to z similar to 2.
VersionFinal published version
SponsorsNational Basic Research Program ("973" Program) of China [2014CB845800]; National Natural Science Foundation of China [11322328, 11433009, 11673068, 11603076]; Youth Innovation Promotion Association [2011231, 2017366]; Key Research Program of Frontier Sciences [QYZDB-SSW-SYS005]; Strategic Priority Research Program "Multi-waveband gravitational wave Universe" of the Chinese Academy of Sciences [XDB23000000]; Natural Science Foundation of Jiangsu Province [BK20161096]; Chinese Academy of Sciences Visiting Professorships [2012T1J0011]; Chinese State Administration of Foreign Experts Affairs [GDJ20120491013]