Abstract
Observed galaxy luminosities (derived from redshifts) hold information on the large-scale peculiar velocity field in the form of spatially correlated scatter, which allows for bounds on bulk flows and the growth rate of matter density perturbations using large galaxy redshift surveys. We apply this luminosity approach to galaxies from the recent SDSS Data Release 13. Our goal is twofold. First, we take advantage of the recalibrated photometry to identify possible systematic errors relevant to our previous analysis of earlier data. Second, we seek improved constraints on the bulk flow and the normalized growth rate f$\sigma_{8}$ at z ~ 0.1. Our results confirm the robustness of our method. Bulk flow amplitudes, estimated in two redshift bins with 0.02 < z$_{1}$ < 0.07 < z$_{2}$ < 0.22, are generally smaller than in previous measurements, consistent with both the updated photometry and expectations for the $\Lambda$CDM model. The obtained growth rate, f$\sigma_{8}$ = 0.48 +/- 0.16, is larger than, but still compatible with, its previous estimate, and closer to the reference value of Planck. Rather than precision, the importance of these results is due to the fact that they follow from an independent method that relies on accurate photometry, which is a top requirement for next-generation photometric catalogs.
Highlights
Cosmology is steadily maturing from a phase driven by high precision to a high-accuracy science
The luminosity method can be used to assess the coherence of the peculiar velocity field, most notably the bulk flow, i.e. the volume average of the peculiar velocity field. This constitutes a second example, this technique has provided an important consistency check to other estimates based on galaxy peculiar velocities and contributed to rule out claims of anomalously large flows that would prove difficult to justify within the standard cosmological cold dark matter ( CDM) scenario (Nusser, Branchini & Davis 2011; Branchini, Davis & Nusser 2012; Feix, Nusser & Branchini 2014)
This mainly applies to the bulk flow estimate since the measurement of the growth rate involves additional information which reduces the impact of systematics
Summary
Cosmology is steadily maturing from a phase driven by high precision to a high-accuracy science. The luminosity method can be used to assess the coherence of the peculiar velocity field, most notably the bulk flow, i.e. the volume average of the peculiar velocity field And this constitutes a second example, this technique has provided an important consistency check to other estimates based on galaxy peculiar velocities and contributed to rule out claims of anomalously large flows that would prove difficult to justify within the standard cosmological cold dark matter ( CDM) scenario (Nusser, Branchini & Davis 2011; Branchini, Davis & Nusser 2012; Feix, Nusser & Branchini 2014). Thanks to a reduction of systematic errors, we will test the robustness of our previous results This mainly applies to the bulk flow estimate since the measurement of the growth rate involves additional information (spatial clustering from spectroscopic redshift surveys) which reduces the impact of systematics. Galaxy redshifts are expressed relative to the rest frame of the cosmic microwave background using the dipole estimate of Fixsen et al (1996)
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