Large-scale collective motion of RFGC galaxies

TL;DR

This study analyzes the large-scale velocity field of 1678 flat edge-on spiral galaxies to estimate cosmological parameters, revealing significant multipole components and providing constraints on Omega_m and sigma_8.

Contribution

It introduces a detailed analysis of the velocity field using multipole decomposition and derives new constraints on cosmological parameters from galaxy peculiar velocities.

Findings

Quadrupole and octopole components are statistically significant.

Estimated cosmological parameter S_8 = 0.91 +/- 0.05.

Provided constraints on Omega_m and sigma_8.

Abstract

We processed the data about radial velocities and HI linewidths for 1678 flat edge-on spirals from the Revised Flat Galaxy Catalogue. We obtained the parameters of the multipole components of large-scale velocity field of collective non-Hubble galaxy motion as well as the parameters of the generalized Tully-Fisher relationship in the "HI line width - linear diameter" version. All the calculations were performed independently in the framework of three models, where the multipole decomposition of the galaxy velocity field was limited to a dipole, quadrupole and octopole terms respectively. We showed that both the quadrupole and the octopole components are statistically significant. On the basis of the compiled list of peculiar velocities of 1623 galaxies we obtained the estimations of cosmological parameters Omega_m and sigma_8. This estimation is obtained in both graphical form and as a constraint of the value S_8=sigma_8(Omega_m/0.3)^0.35 = 0.91 +/- 0.05.