Name: Sukhdeep Singh
Affiliation: Indian Institute of Technology Kharagpur
Conference ID : ASI2022_176
Title : Fast Estimator for bispectrum of 3D cosmological fields
Authors : Abinash Kumar Shaw, Somnath Bharadwaj, Debanjan Sarkar, Arindam Mazumdar, Sukhdeep Singh, Suman Majumdar
Abstract Type: Poster
Abstract Category : General Relativity and Cosmology
Abstract : In the era of precision cosmology, the study of clustering statistics beyond power-spectrum (Fourier transform of 2-point correlation function) is very crucial to capture detailed features of underlying non-Gaussian cosmological fields. Bispectrum (Fourier counterpart of 3-point correlation function), the lowest order statistics sensitive to non-Gaussianity, of density field distribution in real and redshift space provide great deal of cosmological information regarding the physics of the very early Universe, subsequent growth of structures and constraining various model parameters. However, higher order statistics are very computationally expansive due to their high dimensionality. It is necessary to develop their fast and accurate estimators to analyse the enormous amount of data from ongoing and upcoming galaxy surveys like LSST, DESI, EUCLID etc. We have developed a Fast Fourier Transform based estimator of binned bispectrum for 3D cosmological density fields by linearly binning the wave-vector space (k-space) in uniform concentric spherical shells. The parameterization of triangles formed by different wave-vectors (or Fourier modes) is taken in such a way that the shape and size dependence of bispectrum, corresponding to each possible closed triangle configuration, can be studied separately. The estimator is also implemented to analyse the monopole moment of redshift space bispectrum of field possessing linear redshift-space distortion caused by peculiar velocities of galaxies. The estimator is very fast and results are in good agreement with analytical predictions form second order perturbation theory. The estimator can further be used to analyse survey data to explore the features of cosmic fields and extract precious cosmological information.