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Showing 1 to 8 of 8 for “"Primordial non-Gaussianity"”.
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Probing primordial non-Gaussianity using large scale structure
… satellite has lead to a tentative detection of non-Gaussianity. Using the bispectrum statistic applied to the MegaZ catalogue of over 600,000 luminous red galaxies we find new bounds on the large-scale nonGaussianity. We constrain the fNL parameter using a particular type of triangular …
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High-Resolution CMB Bispectrum Estimator
… correlation function, allows us to study weak non-Gaussian signatures of the primordial fluctuations. Primordial non-Gaussianity is a key prediction of many physically well-motivated inflation models, and measuring its shape and amplitude allows us to constrain various models of the early …
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Higher Order Couplings in the Clustering of Biased Tracers of Large-Scale Structure
… In order to extract this information, the non-linearities present in late-time observables provided by LSS surveys must be understood well. In general, there are three main sources of non-linearities: (1) non-linear matter clustering due to gravity; (2) non-linear biasing, i.e. the relation …
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Probing the Cosmological Initial Conditions Using the CMB
… we found (Yadav and Wandelt 2008) evidence for primordial non-Gaussianity of the local type (fNL) in the temperature anisotropy of the Cosmic Microwave Background. Analyzing the bispectrum of the WMAP 3-year data up to lmax=750 we find 27< fNL<147 (95% CL). This amounts to a rejection of fNL=0 …
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Gravitational waves and gauge fields in the early Universe
… lead to the resonant production of Abelian and non-Abelian gauge bosons. We subsequently demonstrate that gravitational wave emission constrains a similar model invoked to resolve the discrepancy in measurements of the present-day expansion rate. Finally, we study gravitational waves induced by …
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Reconstructing the Sky with CMB Lensing methods
… provide powerful tests for parameter tensions, non-Gaussianity, neutrino mass, and modifications to Λ−CDM and gravity. However, such cross-correlations are sensitive to CMB foreground contamination, and the resulting biases represent an important challenge for cosmological analyses. In this …
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Early Seeds and Cosmic Skies: Quantum Origins of the Universe and Insights from Large-Scale Structure
… in-in formalism. Here, we show that for non-dissipative systems, we can calculate correlators using the more widely used in-out formalism. In de Sitter space, we achieve this by extending the expanding Poincaré patch with a contracting one. This leads to simplified calculations with fewer …
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Projected Angular Statistics for Large-scale Structure Cosmology
… matter and dark energy, modified gravity and primordial non- Gaussianity. Galaxy surveys measure (sometimes approximate) redshifts and angular positions of galaxies, which trace the LSS. The natural observables are maps of the galaxy overdensity, projected in redshift bins. Similarly, …