Constraining a Possible Variation of G with Type Ia Supernovae
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 |dot{G}/G| 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.
- Publication:
-
Publications of the Astronomical Society of Australia
- Pub Date:
- March 2014
- DOI:
- 10.1017/pasa.2014.9
- arXiv:
- arXiv:1402.1534
- Bibcode:
- 2014PASA...31...15M
- Keywords:
-
- stars: (supernovae): general;
- gravity;
- (cosmology): distance scale;
- stars: (white dwarfs);
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- to appear in PASA