Large-scale peculiar velocities through the galaxy luminosity function at z ~ 0.1

TL;DR

This paper demonstrates how large galaxy surveys can be used to measure cosmic peculiar velocities by analyzing luminosity variations, providing constraints consistent with the standard cosmological model.

Contribution

It applies a novel method to a large dataset to constrain velocity moments and the matter power spectrum, validating the approach with SDSS data.

Findings

Results agree with the ΛCDM model

Constraints on velocity moments and σ₈ are obtained

Consistent with previous photometric zero-point tilt reports

Abstract

Peculiar motion introduces systematic variations in the observed luminosity distribution of galaxies. This allows one to constrain the cosmic peculiar velocity field from large galaxy redshift surveys. Using around half a million galaxies from the SDSS Data Release 7 at z ~ 0.1, we demonstrate the applicability of this approach to large datasets and obtain bounds on peculiar velocity moments and $\sigma_{8}$, the amplitude of the linear matter power spectrum. Our results are in good agreement with the $\Lambda$CDM model and consistent with the previously reported ~ 1% zero-point tilt in the SDSS photometry. Finally, we discuss the prospects of constraining the growth rate of density perturbations by reconstructing the full linear velocity field from the observed galaxy clustering in redshift space.