Journal
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
Volume -, Issue 12, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/1475-7516/2019/12/028
Keywords
cosmological parameters from LSS; redshift surveys; power spectrum
Funding
- University of Padova under the STARS Grants programme CoG-ITO: Cosmology beyond Gaussianity, Inference, Theory and Observations
- South African Radio Astronomy Observatory
- National Research Foundation [75415]
- UK Science & Technology Facilities Council [ST/N000668/1]
- STFC [ST/S000550/1] Funding Source: UKRI
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The large-scale structure growth index gamma provides a consistency test of the standard cosmology and is a potential indicator of modified gravity. We investigate the constraints on gamma from next-generation spectroscopic surveys, using the power spectrum that is observed in redshift space, i.e., the angular power spectrum. The angular power spectrum avoids the need for an Alcock-Packzynski correction. It also naturally incorporates cosmic evolution and wide-angle effects, without any approximation. We include the cross-correlations between redshift bins, using a hybrid approximation when the total number of bins is computationally unfeasible. We show that the signal-to-noise on gamma increases as the redshift bin-width is decreased. Shot noise per bin also increases - but this is compensated by the increased number of auto- and cross-spectra. In our forecasts, we marginalise over the amplitude of primordial fluctuations and other standard cosmological parameters, including the dark energy equation of state parameter, as well as the clustering bias. Neglecting cross-bin correlations increases the errors by similar to 40-150%. Using only linear scales, we find that a DESI-like BGS survey and an HI intensity mapping survey with the SKA1 precursor MeerKAT deliver similar errors of similar to 4-6%, while a Euclid-like survey and an SKA1 intensity mapping survey give similar to 3% errors.
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