Publications of the Astronomical Society of Australia

Research Article

Constraining a Possible Variation of G with Type Ia Supernovae

Jeremy Moulda1 c1 and Syed A. Uddina1 *

a1 Centre for Astrophysics & Supercomputing, Swinburne University of Technology, 10 John Street, Hawthorn, 3122, Australia

Abstract

Astrophysical cosmology constrains the variation of Newton’s Constant in a manner complementary to laboratory experiments, such as the celebrated lunar laser ranging campaign. Supernova cosmology is an example of the former and has attained campaign status, following planning by a Dark Energy Task Force in 2005. In this paper, we employ the full SNIa data set to the end of 2013 to set a limit on G variation. In our approach, we adopt the standard candle delineation of the redshift distance relation. We set an upper limit on its rate of change of 0.1 parts per billion per year over 9 Gyrs. By contrast, lunar laser ranging tests variation of G over the last few decades. Conversely, one may adopt the laboratory result as a prior and constrain the effect of variable G in dark energy equation of state experiments to δw < 0.02. We also examine the parameterisation G ~ 1 + z. Its short expansion age conflicts with the measured values of the expansion rate and the density in a flat Universe. In conclusion, supernova cosmology complements other experiments in limiting G variation. An important caveat is that it rests on the assumption that the same mass of 56Ni is burned to create the standard candle regardless of redshift. These two quantities, f and G, where f is the Chandrasekhar mass fraction burned, are degenerate. Constraining f variation alone requires more understanding of the SNIa mechanism.

(Received October 28 2013)

(Accepted February 06 2014)

Keywords:

  • stars: (supernovae): general – gravity – (cosmology): distance scale – stars: (white dwarfs)

Correspondence

c1 Corresponding author. Email: jmould@groupwise.swin.edu.au

Footnotes

*  CAASTRO, http://www.caastro.org

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