Probing large-scale structure with MeerKAT, the SKA and other surveys
Loading...
Date
2024
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Western Cape
Abstract
The fluctuations produced during cosmic inflation may exhibit non-Gaussian characteristics that are imprinted in the large-scale structure of the Universe. This non-Gaussian imprint is an ultra-large scale signal that can be detected using the power spectrum. We focus on the local-type non-Gaussianity fNL and employ a multi-tracer analysis that combines different probes in order to mitigate cosmic variance and maximize the non-Gaussian signal. In this work we combine the 21cm intensity mapping survey optimised for interferometer mode with spectroscopic galaxy surveys. Combining the same 21 cm experiments, including also single-dish surveys, with photometric galaxy surveys. The 21 cm single-dish surveys are based on MeerKAT and SKAO and the interferometric surveys are alike to HIRAX and PUMA. We implement foreground-avoidance filters and utilize models for the 21 cm thermal noise associated with single-dish and interferometer modes. The photometric galaxy surveys are similar to the DES and LSST while spectroscopic galaxy surveys are similar to the Euclid and MeggaMapper. Our multi-tracer Fisher forecasts show that combining spectroscopic galaxy surveys with 21 cm intensity mapping surveys in interferometer mode could lead to a ∼
20-30% improvement in the precision on this non-Gaussian signal. Furthermore, we investigate the effects on constraints of varying the parameter of non-Gaussian galaxy assembly bias and of varying the parameters of the intensity mapping foreground filters. We find that the non-Gaussian galaxy assembly bias parameter causes a greater change in the constraints on local primordial non-Gaussianity than the foreground filter parameters. Again our multi-tracer Fisher forecasts show a better precision for the combination of the photometric galaxy surveys and 21 cm interferometric surveys than with the 21 cm single-dish surveys - leading to at most an improvement of 23% in the former case and 16% in the latter case.
Furthermore, we examine the impact of varying the foreground filter parameter, redshift range and sky area on the derived constraint. We find that the fNL constraint is highly sensitive to both the redshift range and sky area. The foreground filter parameter shows negligible effect.
Description
Keywords
large-scale structure, power spectrum, mapping survey