Measuring our velocity from fluctuations in number counts

Abstract

Our velocity relative to the cosmic microwave background (CMB) generates a dipole from the CMB monopole, which was accurately measured by COBE. The relative velocity also modulates and aberrates the CMB fluctuations, generating a small signature of statistical isotropy violation in the covariance matrix. This signature was first measured by Planck 2013. Galaxy surveys are similarly affected by a Doppler boost. The dipole generated from the number count monopole has been extensively discussed, and measured (at very low accuracy) in the NVSS and TGSS radio continuum surveys. For the first time, we present an analysis of the Doppler imprint on the number count fluctuations, using the bipolar spherical harmonic formalism to quantify these effects. Next-generation wide-area surveys with a high redshift range are needed to detect the small Doppler signature in number count fluctuations. We show that radio continuum surveys with the SKA should enable a detection at $\gtrsim 3\sigma$ in Phase 2, with marginal detection possible in Phase 1.

Version accepted by JCAP

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Cited by in corpus (10)

• Testing the standard model of cosmology with the SKA: the cosmic radio dipole
• Doppler boosting the stochastic gravitational wave background
• Bayesian estimation of our local motion from the Planck-2018 CMB temperature map
• Testing the Cosmological Principle in the radio sky
• Non-comoving Cosmology
• Generalisation of the Kaiser Rocket effect in general relativity in the wide-angle galaxy 2-point correlation function
• Footprints of Doppler and Aberration Effects in CMB Experiments: Statistical and Cosmological Implications
• The Science of Fundamental Catalogs
• Statistical effects of the observer's peculiar velocity on source number counts
• Peculiar velocity effects on the Hubble constant from time-delay cosmography