1,721,299 research outputs found
{The DECADE cosmic shear project I: A new weak lensing shape catalog of 107 million galaxies}
No full textAre cosmological data sets consistent with each other within the Λ cold dark matter model?
No full textWe use a complete and rigorous statistical indicator to measure the level of concordance between cosmological data sets, without relying on the inspection of the marginal posterior distribution of some selected parameters. We apply this test to state of the art cosmological data sets, to assess their agreement within the Λ cold dark matter model. We find that there is a good level of concordance between all the experiments with one noticeable exception. There is substantial evidence of tension between the cosmic microwave background temperature and polarization measurements of the Planck satellite and the data from the CFHTLenS weak lensing survey even when applying ultraconservative cuts. These results robustly point toward the possibility of having unaccounted systematic effects in the data, an incomplete modeling of the cosmological predictions or hints toward new physical phenomena
Reconstructing gravity on cosmological scales
No full textWe present the data-driven late-Time reconstruction of gravitational theories and dark energy models on cosmological scales. We showcase the power of present cosmological probes at constraining these models and quantify the knowledge of their properties that can be acquired through state of the art data. This reconstruction exploits the power of the effective field theory approach to dark energy and modified gravity phenomenology, which compresses the freedom in defining such models into a finite set of functions that can be reconstructed across cosmic times using cosmological data. We consider several model classes described within this framework and thoroughly discuss their phenomenology and data implications. We find that some models can alleviate the present discrepancy in the determination of the Hubble constant as inferred from the cosmic microwave background and as directly measured. This results in a statistically significant preference for the reconstructed theories over the standard cosmological model
Can modified gravity models reconcile the tension between the CMB anisotropy and lensing maps in Planck-like observations?
Full text linkTheoretical Physic
Concordance and discordance in cosmology
No full textThe success of present and future cosmological studies is tied to the ability to detect discrepancies in complex data sets within the framework of a cosmological model. Tensions caused by the presence of unknown systematic effects need to be isolated and corrected to increase the overall accuracy of parameter constraints, while discrepancies due to new physical phenomena need to be promptly identified. We develop a full set of estimators of internal and mutual agreement and disagreement, whose strengths complement each other. These estimators take into account the effect of prior information and compute the statistical significance of both tensions and confirmatory biases. The estimators that we present optimally weight all parameter space directions that are either fully constrained by the data or the prior, allowing for complete and fair degree of freedom counting. We apply them to a wide range of state-of-the-art cosmological probes and show that these estimators can be easily used, regardless of model and data complexity. We derive a series of results that show that discrepancies indeed arise within the standard ΛCDM model. Several of them exceed the probability threshold of 95% and deserve a dedicated effort to understand their origin
Non-Gaussian estimates of tensions in cosmological parameters
No full textWe discuss how to efficiently and reliably estimate the level of agreement and disagreement on parameter determinations from different experiments, fully taking into account non-Gaussianities in the parameter posteriors. We develop two families of scalable algorithms that allow us to perform this type of calculations in an increasing number of dimensions and for different levels of tensions. One family of algorithms rely on kernel density estimates of posterior distributions while the other relies on machine learning modeling of the posterior distribution with normalizing flows. We showcase their effectiveness and accuracy with a set of benchmark examples and find both methods agree with each other and the true tension within in difficult cases and generally to or better. This allows us to study the level of internal agreement between different measurements of the clustering of cosmological structures from the Dark Energy Survey and their agreement with measurements of the cosmic microwave background from the Planck satellite
{The DECADE cosmic shear project II: photometric redshift calibration of the source galaxy sample}
No full text{Constraining the baryonic feedback with cosmic shear using the DES Year-3 small-scale measurements}
No full text{Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck. II. Cross-correlation measurements and cosmological constraints}
No full textCross-correlations of galaxy positions and galaxy shears with maps of gravitational lensing of the cosmic microwave background (CMB) are sensitive to the distribution of large-scale structure in the Universe. Such cross-correlations are also expected to be immune to some of the systematic effects that complicate correlation measurements internal to galaxy surveys. We present measurements and modeling of the cross-correlations between galaxy positions and galaxy lensing measured in the first three years of data from the Dark Energy Survey with CMB lensing maps derived from a combination of data from the 2500 deg2 SPT-SZ survey conducted with the South Pole Telescope and full-sky data from the Planck satellite. The CMB lensing maps used in this analysis have been constructed in a way that minimizes biases from the thermal Sunyaev Zel'dovich effect, making them well suited for cross-correlation studies. The total signal-to-noise of the cross-correlation measurements is 23.9 (25.7) when using a choice of angular scales optimized for a linear (nonlinear) galaxy bias model. We use the cross-correlation measurements to obtain constraints on cosmological parameters. For our fiducial galaxy sample, which consist of four bins of magnitude-selected galaxies, we find constraints of omega m 1/4 0.272 thorn 0.032 pffiffiffiffiffiffiffiffiffiffiffiffiffiffi-0.052 and S8 equivalent to sigma 8 omega m=0.3 1/4 0.736 thorn 0.032 -0.028 (omega m 1/40.245 thorn 0.0-0.04426 and S8 1/40.734 thorn 0.035 -0.028 ) when assuming linear (nonlinear) galaxy bias in our modeling. Considering only the cross-correlation of galaxy shear with CMB lensing, we find omega m 1/4 0.270 thorn 0.043 -0.061 and S8 1/4 0.740 thorn 0.034 -0.029 . Our constraints on S8 are consistent with recent cosmic shear measurements, but lower than the values preferred by primary CMB measurements from Planck
{Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck. I. Construction of CMB lensing maps and modeling choices}
No full textJoint analyses of cross-correlations between measurements of galaxy positions, galaxy lensing, and lensing of the cosmic microwave background (CMB) offer powerful constraints on the large-scale structure of the Universe. In a forthcoming analysis, we will present cosmological constraints from the analysis of such cross-correlations measured using Year 3 data from the Dark Energy Survey (DES), and CMB data from the South Pole Telescope (SPT) and Planck. Here we present two key ingredients of this analysis: (1) an improved CMB lensing map in the SPT-SZ survey footprint and (2) the analysis methodology that will be used to extract cosmological information from the cross-correlation measurements. Relative to previous lensing maps made from the same CMB observations, we have implemented techniques to remove contamination from the thermal Sunyaev Zel'dovich effect, enabling the extraction of cosmological information from smaller angular scales of the cross-correlation measurements than in previous analyses with DES Year 1 data. We describe our model for the cross-correlations between these maps and DES data, and validate our modeling choices to demonstrate the robustness of our analysis. We then forecast the expected cosmological constraints from the galaxy survey-CMB lensing auto and cross-correlations. We find that the galaxy-CMB lensing and galaxy shear-CMB lensing correlations will on their own provide a pffiffiffiffiffiffiffiffiffiffiffiffiffifficonstraint on S8 1/4 sigma 8 omega m=0.3 at the few percent level, providing a powerful consistency check for the DES-only constraints. We explore scenarios where external priors on shear calibration are removed, finding that the joint analysis of CMB lensing cross-correlations can provide constraints on the shear calibration amplitude at the 5% to 10% level
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