Probing IGM large-scale flows: warps in galaxies at shells of voids

TL;DR

This study investigates the relationship between galaxy warps and their orientation relative to cosmic voids to detect intergalactic medium flows, using statistical analysis of SDSS galaxy data compared to theoretical models.

Contribution

Develops a statistical method to analyze galaxy warp-inclination correlation and applies it to SDSS data to test for intergalactic medium flows around voids.

Findings

Weak evidence against null hypothesis at 94.4% confidence level

Cannot conclusively detect radial flows in the intergalactic medium

Sets an upper limit on baryonic matter density of radial flows

Abstract

CONTEXT. Hydrodynamical cosmological simulations predict flows of the intergalactic medium along the radial vector of the voids, approximately in the direction of the infall of matter at the early stages of the galaxy formation. AIMS. These flows might be detected by analysing the dependence of the warp amplitude on the inclination of the galaxies at the shells of the voids with respect to the radial vector of the voids. This analysis will be the topic of this paper. METHODS. We develop a statistical method of analysing the correlation of the amplitude of the warp and the inclination of the galaxy at the void surface. This is applied to a sample of 97 edge-on galaxies from the Sloan Digital Sky Survey. Our results are compared with the theoretical expectations, which are also derived in this paper. RESULTS. Our results allow us to reject the null hypothesis (i.e., the non-correlation of the warp amplitude and the inclination of the galaxy with respect to the void surface) at 94.4% C. L., which is not conclusive. The absence of the radial flows cannot be excluded at present, although we can put a constraint on the maximum average density of baryonic matter of the radial flows of <rho_b> <~ 4 Omega_b rho_crit.