The paper focuses on constraining primordial non-Gaussianity, specifically the local-type non-Gaussianity parameter fNL, by employing a multi-tracer analysis that combines different cosmological probes. The authors consider combining photometric galaxy surveys (similar to DES and LSST) with 21cm intensity mapping surveys in both single-dish (MeerKAT-like and SKA-like) and interferometric (HIRAX-like and PUMA-like) modes.
The key highlights are:
The multi-tracer approach can effectively mitigate the impact of cosmic variance and maximize the non-Gaussian signal, leading to tighter constraints on fNL compared to using a single tracer.
Combining photometric galaxy surveys with 21cm interferometric surveys can improve the precision on fNL by up to 23% compared to using the photometric surveys alone. The improvement is up to 16% when combining with 21cm single-dish surveys.
The authors investigate the impact of varying the foreground filter parameter, redshift range, and sky area on the derived fNL constraint. They find that the constraint is highly sensitive to both the redshift range and sky area, while the foreground filter parameter shows a negligible effect.
The multi-tracer analysis is more effective at mitigating the loss of long modes due to foreground removal, especially when the overlapping sky area and redshift range are larger.
Compared to photometric surveys, 21cm intensity mapping surveys provide stronger constraints on the spectral index ns and the amplitude of primordial fluctuations As, despite offering weaker constraints on fNL.
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arxiv.org
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by Mponeng Kopa... at arxiv.org 10-01-2024
https://arxiv.org/pdf/2409.19383.pdfDeeper Inquiries