Measuring cosmic velocities with 21cm intensity mapping and galaxy redshift survey cross-correlation dipoles

Abstract

We investigate the feasibility of measuring the effects of peculiar velocities in large-scale structure using the dipole of the redshift-space cross-correlation function. We combine number counts of galaxies with brightness-temperature fluctuations from 21cm intensity mapping, demonstrating that the dipole may be measured at modest significance ($\lesssim 2\sigma$) by combining the upcoming radio survey CHIME with the future redshift surveys of DESI and Euclid. More significant measurements ($\lesssim 10\sigma$) will be possible by combining intensity maps from the SKA with these of DESI or Euclid, and an even higher significance measurement ($\lesssim 100\sigma$) may be made by combining observables completely internally to the SKA. We account for effects such as contamination by wide-angle terms, interferometer noise and beams in the intensity maps, non-linear enhancements to the power spectrum, stacking multiple populations, sensitivity to the magnification slope, and the possibility that number counts and intensity maps probe the same tracers. We also derive a new expression for the covariance matrix of multi-tracer redshift-space correlation function estimators with arbitrary orientation weights, which may be useful for upcoming surveys aiming at measuring redshift-space clustering with multiple tracers.

24 pages, 8 figures. A few typos corrected, results unchanged

References in corpus (8)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• New Perspective on Galaxy Clustering as a Cosmological Probe: General Relativistic Effects
• Measurement of 21 cm brightness fluctuations at z ~ 0.8 in cross-correlation
• Late-time cosmology with 21cm intensity mapping experiments
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• Testing General Relativity with 21 cm intensity mapping
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• A null test to probe the scale-dependence of the growth of structure as a test of General Relativity
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• Testing the equivalence principle on cosmological scales using the odd multipoles of galaxy cross-power spectrum and bispectrum
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• Anti-symmetric clustering signals in the observed power spectrum
• Screened fifth forces in parity-breaking correlation functions
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• Testing General Relativity with Cosmological Large Scale Structure
• Testing local position invariance with odd multipoles of galaxy clustering statistics
• Multi-wavelength spectroscopic probes: prospects for primordial non-Gaussianity and relativistic effects
• Origin & evolution of the Universe
• Gravitational redshift from large-scale structure: nonlinearities, antisymmetries, and the dipole
• Robust Intensity Mapping Analysis against Foregrounds for the Epoch of Reionization
• Visualising relativistic effects in redshift space distortions of large scale structure