1612.03034
First test of Verlinde's theory of emergent gravity using weak gravitational lensing measurements
Brouwer, et al
Verlinde (2016) proposed that the observed excess gravity in galaxies and clusters is the consequence of Emergent Gravity (EG). In this theory the standard gravitational laws are modified on galactic and larger scales due to the displacement of dark energy by baryonic matter. EG gives an estimate of the excess gravity (described as an apparent DM density) in terms of the baryonic mass distribution and the Hubble parameter. In this work, present the first test of EG using WL, within the regime of validity of the current model. Although there is no direct description of lensing and cosmology in EG yet, can make a reasonable estimate of the expected lensing signal of low redshift galaxies by assuming a BG LCDM cosmology. Measure the (apparent) average surface mass density profiles of 33,613 isolated central galaxies, and compare them to those predicted by EG based on the galaxies' baryonic masses. To this end, employ the ~180 sq.deg. overlap of KiDS with the spectroscopic GAMA survey. Find that the prediction from EG, despite requiring no free parameters, is in good agreement with the observed gglensing profiles in 4 different stellar mass bins. Although this performance is remarkable, this study is only a first step. Further advancements on both the theoretical framework and observational tests of EG are needed before it can be considered a fully developed and solidly tested theory.
1612.03121
Integrated cosmological probes: extended analysis
Nicola, Refregier, Amara
Recent progress in cosmology has relied on combining different cosmo probes. In earlier work, implemented an integrated approach to cosmology where the probes are combined into a common framework at the map level. This has the advantage of taking full account of the correlations between the different probes, to provide a stringent test of systematics and the validity of the cosmo model. Extend this analysis to include not only CMB temperature, galaxy clustering, WL from SDSS but also CMB lensing, WL from DES SV, Type Ia SNe and H0 measurements. This yields 12 auto and cross power spectra as well as BG probes. Furthermore, extend the treatment of systematic uncertainties. For LCDM, find results that are consistent with earlier work. Given the enlarged data set and systematics treatment, this confirms the robustness of the analysis and results. Furthermore, find that the best-fit cosmo model gives a good fit to the data considered with no signs of tensions within the analysis. Also find the constraints to be consistent with this found by WMAP9, SPT and ACT and the KiDS WL survey. Comparing with the Planck Collaboration results, see a broad agreement, but there are indications of a tension from the marginalized constraints in most pairs of cosmological parameters. Since the analysis includes CMB temperature Planck data at 10<ell<610, the tension appears to arise between the Planck high-ell and the other measurements. Furthermore, find the constraints on the probe calibration parameters to be in agreement with expectations, showing that the datasets are mutually consistent. In particular, this yields a confirmation of the amplitude calibration of the WL measurements from SDSS, DES SV and Planck CMB lensing from the integrated analysis.
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