Measuring our peculiar velocity from spectroscopic redshift surveys

TL;DR

This paper proposes a new method to measure our peculiar velocity using the oscillatory FOTO effect in galaxy power spectra from redshift surveys, enabling tests of cosmological models and the CMB dipole.

Contribution

It introduces a novel technique leveraging redshift corrections to determine the magnitude and direction of our peculiar velocity from galaxy surveys.

Findings

FOTO effect can be detected with high signal-to-noise ratio in mock surveys.

Redshift corrections do not erase the FOTO signal, enabling velocity measurement.

Method can test CMB dipole interpretation and constrain cosmological parameters.

Abstract

Our peculiar velocity imprints a dipole on galaxy density maps derived from redshift surveys. The dipole gives rise to an oscillatory signal in the multipole moments of the observed power spectrum which we indicate as the finger-of-the-observer (FOTO) effect. Using a suite of large mock catalogues mimicking ongoing and future $\textrm{H}\alpha$- and $\textrm{H}\scriptstyle\mathrm{I}$-selected surveys, we demonstrate that the oscillatory features can be measured with a signal-to-noise ratio of up to 7 (depending on the sky area coverage and provided that observational systematics are kept under control on large scales). We also show that the FOTO effect cannot be erased by correcting the individual galaxy redshifts. On the contrary, by leveraging the power of the redshift corrections, we propose a novel method to determine both the magnitude and the direction of our peculiar velocity. After applying this technique to our mock catalogues, we conclude that it can be used to either test the kinematic interpretation of the temperature dipole in the cosmic microwave background or to extract cosmological information such as the matter density parameter and the equation of state of dark energy.