de Putter, R., Verde, L., & Jimenez, R. (2013). Testing LTB void models without the cosmic microwave background or large scale structure: new constraints from galaxy ages. J. Cosmol. Astropart. Phys., 02(2), 047–22pp.
Abstract: We present new observational constraints on inhomogenous models based on observables independent of the CMB and large-scale structure. Using Bayesian evidence we find very strong evidence for homogeneous LCDM model, thus disfavouring inhomogeneous models. Our new constraints are based on quantities independent of the growth of perturbations and rely on cosmic clocks based on atomic physics and on the local density of matter.
|
Das, S., de Putter, R., Linder, E. V., & Nakajima, R. (2012). Weak lensing cosmology beyond Lambda CDM. J. Cosmol. Astropart. Phys., 11(11), 23pp.
Abstract: Weak gravitational lensing is one of the key probes of the cosmological model, dark energy, and dark matter, providing insight into both the cosmic expansion history and large scale structure growth history. Taking into account a broad spectrum of physics affecting growth – dynamical dark energy, extended gravity, neutrino masses, and spatial curvature – we analyze the cosmological constraints. Similarly we consider the effects of a range of systematic uncertainties, in shear measurement, photometric redshifts, intrinsic alignments, and the nonlinear power spectrum, on cosmological parameter extraction. We also investigate, and provide fitting formulas tor, the influence of survey parameters such as redshift depth, galaxy number densities, and sky area on the cosmological constraints in the beyond-ACDM parameter space. Finally, we examine the robustness of results for different fiducial cosmologies.
|
Cervantes-Cota, J. L., de Putter, R., & Linder, E. V. (2010). Induced gravity and the attractor dynamics of dark energy/dark matter. J. Cosmol. Astropart. Phys., 12(12), 019–20pp.
Abstract: Attractor solutions that give dynamical reasons for dark energy to act like the cosmological constant, or behavior close to it, are interesting possibilities to explain cosmic acceleration. Coupling the scalar field to matter or to gravity enlarges the dynamical behavior; we consider both couplings together, which can ameliorate some problems for each individually. Such theories have also been proposed in a Higgs-like fashion to induce gravity and unify dark energy and dark matter origins. We explore restrictions on such theories due to their dynamical behavior compared to observations of the cosmic expansion. Quartic potentials in particular have viable stability properties and asymptotically approach general relativity.
|
Barenboim, G., Fernandez-Martinez, E., Mena, O., & Verde, L. (2010). The dark side of curvature. J. Cosmol. Astropart. Phys., 03(3), 008–17pp.
Abstract: Geometrical tests such as the combination of the Hubble parameter H(z) and the angular diameter distance d(A)(z) can, in principle, break the degeneracy between the dark energy equation of state parameter w(z), and the spatial curvature Omega(k) in a direct, model-independent way. In practice, constraints on these quantities achievable from realistic experiments, such as those to be provided by Baryon Acoustic Oscillation (BAO) galaxy surveys in combination with CMB data, can resolve the cosmic confusion between the dark energy equation of state parameter and curvature only statistically and within a parameterized model for w(z). Combining measurements of both H(z) and d(A)(z) up to sufficiently high redshifts z similar to 2 and employing a parameterization of the redshift evolution of the dark energy equation of state are the keys to resolve the w(z) – Omega(k) degeneracy.
|
Anderson, L. et al, de Putter, R., & Mena, O. (2012). The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: baryon acoustic oscillations in the Data Release 9 spectroscopic galaxy sample. Mon. Not. Roy. Astron. Soc., 427(4), 3435–3467.
Abstract: We present measurements of galaxy clustering from the Baryon Oscillation Spectroscopic Survey (BOSS), which is part of the Sloan Digital Sky Survey III (SDSS-III). These use the Data Release 9 (DR9) CMASS sample, which contains 264 283 massive galaxies covering 3275 square degrees with an effective redshift z = 0.57 and redshift range 0.43 < z < 0.7. Assuming a concordance Lambda CDM cosmological model, this sample covers an effective volume of 2.2 Gpc(3), and represents the largest sample of the Universe ever surveyed at this density, (n) over bar approximate to 3 x 10(-4) h(-3) Mpc(3). We measure the angle-averaged galaxy correlation function and power spectrum, including density-field reconstruction of the baryon acoustic oscillation (BAO) feature. The acoustic features are detected at a significance of 5 sigma in both the correlation function and power spectrum. Combining with the SDSS-II luminous red galaxy sample, the detection significance increases to 6.7 sigma. Fitting for the position of the acoustic features measures the distance to z = 0.57 relative to the sound horizon D-V/r(s) = 13.67 +/ 0.22 at z = 0.57. Assuming a fiducial sound horizon of 153.19 Mpc, which matches cosmic microwave background constraints, this corresponds to a distance D-V (z = 0.57) = 2094 +/- 34 Mpc. At 1.7 per cent, this is the most precise distance constraint ever obtained from a galaxy survey. We place this result alongside previous BAO measurements in a cosmological distance ladder and find excellent agreement with the current supernova measurements. We use these distance measurements to constrain various cosmological models, finding continuing support for a flat Universe with a cosmological constant.
|
