Abstract
We present constraints on extensions of the minimal cosmological models dominated by dark matter and dark energy, and , by using a combined analysis of galaxy clustering and weak gravitational lensing from the first-year data of the Dark Energy Survey (DES Y1) in combination with external data. We consider four extensions of the minimal dark energy-dominated scenarios: (1) nonzero curvature , (2) number of relativistic species different from the standard value of 3.046, (3) time-varying equation-of-state of dark energy described by the parameters and (alternatively quoted by the values at the pivot redshift, , and ), and (4) modified gravity described by the parameters and that modify the metric potentials. We also consider external information from Planck cosmic microwave background measurements; baryon acoustic oscillation measurements from SDSS, 6dF, and BOSS; redshift-space distortion measurements from BOSS; and type Ia supernova information from the Pantheon compilation of datasets. Constraints on curvature and the number of relativistic species are dominated by the external data; when these are combined with DES Y1, we find at the 68% confidence level, and the upper limit at 68% (95%) confidence, assuming a hard prior . For the time-varying equation-of-state, we find the pivot value at pivot redshift from DES alone, and at from DES Y1 combined with external data; in either case we find no evidence for the temporal variation of the equation of state. For modified gravity, we find the present-day value of the relevant parameters to be from DES Y1 alone, and from DES Y1 combined with external data. These modified-gravity constraints are consistent with predictions from general relativity.
1 More- Received 12 October 2018
DOI:https://doi.org/10.1103/PhysRevD.99.123505
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