Differentiating dark energy and modified gravity with galaxy redshift surveys

By Yun Wang. 2007

135 citations recorded by the source corpus.

The observed cosmic acceleration today could be due to an unknown energy component (dark energy), or a modification to general relativity (modified gravity). If dark energy models and modified gravity models are required to predict the same cosmic expansion history H(z), they will predict different growth rates for cosmic large scale structure, fg(z). If gravity is not modified, the measured H(z) leads to a unique prediction for fg(z), fgH(z), if dark energy and dark matter are separate. Comparing fgH(z) with the measured fg(z) provides a transparent and straightforward test of gravity. We show that a simple χ2 test provides a general figure of merit for our ability to distinguish between dark energy and modified gravity given the measured H(z) and fg(z). We find that a magnitude-limited NIR galaxy redshift survey covering >10 000 (deg)2 and a redshift range of 0.5<z<2 can be used to measure H(z) to 1–2% accuracy via baryon acoustic oscillation measurements, and fg(z) to the accuracy of a few per cent via the measurement of redshift-space distortions and the bias factor which describes how light traces mass. We show that if the H(z) data are fitted by both a DGP gravity model and an equivalent dark energy model that predict the same H(z), a survey area of 11 931 (deg)2 is required to rule out the DGP gravity model at the 99.99% confidence level. It is feasible for such a galaxy redshift survey to be carried out by the next generation space missions from NASA and ESA, and it will revolutionize our understanding of the universe by differentiating between dark energy and modified gravity.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/5081014b8459cf7d171d2012006b3759afcc366d

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

The 6dF Galaxy Survey: z \approx 0 measurement of the growth rate and sigma_8 (2012, background): “It is interesting to note in this context the fact that a different form of gravitational interaction on large scales could be responsible for the accelerating expansion of the Universe (e.g. Dvali, Gabadadze & Porrati 2000; Wang 2008).”
The WiggleZ Dark Energy Survey: the growth rate of cosmic structure since redshift z=0.9 (2011, background): “Further observational data is required to distinguish clearly between the subtly-varying predictions of these very different physical models (e.g., Linder 2005, Wang 2008, Wiltshire 2009).”
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS anisotropic galaxy clustering (2013, background): “…clustering allows us to differentiate smooth dark energy and modified gravity as the cause for cosmic acceleration through the simultaneous measurements of the cosmic expansion history H(z) and the growth rate of cosmic large scale structure, f(z) (Guzzo et al. 2008; Wang 2008; Blake et al. 2012).”