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Register a new userConstraints on massive vector dark energy models from integrated Sachs-Wolfe-galaxy cross-correlations
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The gravitational-wave event GW170817, together with the electromagnetic counterpart, shows that the speed of tensor perturbations $c_T$ on the cosmological background is very close to that of light $c$ for the redshift $z<0.009$. In generalized Proca theories, the Lagrangians compatible with the condition $c_T=c$ are constrained to be derivative interactions up to cubic order, besides those corresponding to intrinsic vector modes. We place observational constraints on a dark energy model in cubic-order generalized Proca theories with intrinsic vector modes by running the Markov chain Monte Carlo (MCMC) code. We use the cross-correlation data of the integrated Sachs-Wolfe (ISW) signal and galaxy distributions in addition to the data sets of cosmic microwave background, baryon acoustic oscillations, type Ia supernovae, local measurements of the Hubble expansion rate, and redshift-space distortions. We show that, unlike cubic-order scalar-tensor theories, the existence of intrinsic vector modes allows the possibility for evading the ISW-galaxy anticorrelation incompatible with the current observational data. As a result, we find that the dark energy model in cubic-order generalized Proca theories exhibits a better fit to the data than the cosmological constant, even by including the ISW-galaxy correlation data in the MCMC analysis.
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We present constraints on extensions of the minimal cosmological models dominated by dark matter and dark energy, $Lambda$CDM and $w$CDM, 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 $Omega_k$, 2) number of relativistic species $N_{rm eff}$ different from the standard value of 3.046, 3) time-varying equation-of-state of dark energy described by the parameters $w_0$ and $w_a$ (alternatively quoted by the values at the pivot redshift, $w_p$, and $w_a$), and 4) modified gravity described by the parameters $mu_0$ and $Sigma_0$ that modify the metric potentials. We also consider external information from Planck CMB measurements; BAO measurements from SDSS, 6dF, and BOSS; RSD measurements from BOSS; and SNIa information from the Pantheon compilation. Constraints on curvature and the number of relativistic species are dominated by the external data; when these are combined with DES Y1, we find $Omega_k=0.0020^{+0.0037}_{-0.0032}$ at the 68% confidence level, and $N_{rm eff}<3.28, (3.55)$ at 68% (95%) confidence. For the time-varying equation-of-state, we find the pivot value $(w_p, w_a)=(-0.91^{+0.19}_{-0.23}, -0.57^{+0.93}_{-1.11})$ at pivot redshift $z_p=0.27$ from DES alone, and $(w_p, w_a)=(-1.01^{+0.04}_{-0.04}, -0.28^{+0.37}_{-0.48})$ at $z_p=0.20$ 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 $Sigma_0= 0.43^{+0.28}_{-0.29}$ from DES Y1 alone, and $(Sigma_0, mu_0)=(0.06^{+0.08}_{-0.07}, -0.11^{+0.42}_{-0.46})$ from DES Y1 combined with external data, consistent with predictions from GR.
We determine constraints on spatially-flat tilted dynamical dark energy XCDM and $phi$CDM inflation models by analyzing Planck 2015 cosmic microwave background (CMB) anisotropy data and baryon acoustic oscillation (BAO) distance measurements. XCDM is a simple and widely used but physically inconsistent parameterization of dynamical dark energy, while the $phi$CDM model is a physically consistent one in which a scalar field $phi$ with an inverse power-law potential energy density powers the currently accelerating cosmological expansion. Both these models have one additional parameter compared to standard $Lambda$CDM and both better fit the TT + lowP + lensing + BAO data than does the standard tilted flat-$Lambda$CDM model, with $Delta chi^2 = -1.26 (-1.60)$ for the XCDM ($phi$CDM) model relative to the $Lambda$CDM model. While this is a 1.1$sigma$ (1.3$sigma$) improvement over standard $Lambda$CDM and so not significant, dynamical dark energy models cannot be ruled out. In addition, both dynamical dark energy models reduce the tension between the Planck 2015 CMB anisotropy and the weak lensing $sigma_8$ constraints.
We present the strongest robust constraints on primordial non-Gaussianity (PNG) from currently available galaxy surveys, combining large-scale clustering measurements and their cross-correlations with the cosmic microwave background. We update the data sets used by Giannantonio et al. (2012), and broaden that analysis to include the full set of two-point correlation functions between all surveys. In order to obtain the most reliable constraints on PNG, we advocate the use of the cross-correlations between the catalogs as a robust estimator and we perform an extended analysis of the possible systematics to reduce their impact on the results. To minimize the impact of stellar contamination in our luminous red galaxy (LRG) sample, we use the recent Baryon Oscillations Spectroscopic Survey catalog of Ross et al. (2011). We also find evidence for a new systematic in the NVSS radio galaxy survey similar to, but smaller than, the known declination-dependent issue; this is difficult to remove without affecting the inferred PNG signal, and thus we do not include the NVSS auto-correlation function in our analyses. We find no evidence of primordial non-Gaussianity; for the local-type configuration we obtain for the skewness parameter $ -36 < f_{mathrm{NL}} < 45 $ at 95 % c.l. ($5 pm 21$ at $1sigma$) when using the most conservative part of our data set, improving previous results; we also find no evidence for significant kurtosis, parameterized by $g_{mathrm{NL}}$. In addition to PNG, we simultaneously constrain dark energy and find that it is required with a form consistent with a cosmological constant.
I present to this conference our latest measurements of the integrated Sachs-Wolfe (ISW) effect. After a brief review of the reasons for which this effect arises and of the technique to detect it by cross-correlating the cosmic microwave background (CMB) with the large scale structure of the Universe (LSS), I describe the current state of the art measurement. This is obtained from a combined analysis of six different galaxy datasets, and has a significance level of ~ 4.5 sigma. I then describe the cosmological implications, which show agreement with a flat LCDM model with Omega_m = 0.20 +0.19 -0.11 at 95% confidence level. I finally show how these data can be used to constrain modified gravity theories, focusing in particular on the Dvali-Gabadaze-Porrati (DGP) model.
New physics increasing the expansion rate just prior to recombination is among the least unlikely solutions to the Hubble tension, and would be expected to leave an important signature in the early Integrated Sachs-Wolfe (eISW) effect, a source of Cosmic Microwave Background (CMB) anisotropies arising from the time-variation of gravitational potentials when the Universe was not completely matter dominated. Why, then, is there no clear evidence for new physics from the CMB alone, and why does the $Lambda$CDM model fit CMB data so well? These questions and the vastness of the Hubble tension theory model space motivate general consistency tests of $Lambda$CDM. I perform an eISW-based consistency test of $Lambda$CDM introducing the parameter $A_{rm eISW}$, which rescales the eISW contribution to the CMB power spectra. A fit to Planck CMB data yields $A_{rm eISW}=0.988 pm 0.027$, in perfect agreement with the $Lambda$CDM expectation $A_{rm eISW}=1$, and posing an important challenge for early-time new physics, which I illustrate in a case study focused on early dark energy (EDE). I explicitly show that the increase in $omega_c$ needed for EDE to preserve the fit to the CMB, which has been argued to worsen the fit to weak lensing and galaxy clustering measurements, is specifically required to lower the amplitude of the eISW effect, which would otherwise exceed $Lambda$CDMs prediction by $approx 20%$: this is a generic problem beyond EDE and likely applying to most models enhancing the expansion rate around recombination. Early-time new physics models invoked to address the Hubble tension are therefore faced with the significant challenge of making a similar prediction to $Lambda$CDM for the eISW effect, while not degrading the fit to other measurements in doing so.
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