A New Perspective on the Large-Scale Tidal Effect on the Galaxy Luminosity and Morphology

TL;DR

This study investigates how the large-scale tidal environment influences galaxy luminosity and morphology, revealing that more luminous galaxies tend to reside in regions with lower tidal coherence, with some variations based on galaxy type and environment.

Contribution

It introduces a novel analysis of tidal coherence's impact on galaxy properties, controlling for local density, and finds consistent trends across different galaxy types and environments.

Findings

Luminous galaxies are associated with lower tidal coherence.

Tidal coherence trends are robust across smoothing scales.

Different galaxy types show varying dependence on tidal coherence.

Abstract

We study the mean tidal coherence of galaxy environments as a function of intrinsic luminosity determined by the absolute $r$-band magnitude. The tidal coherence of a galaxy environment is estimated as the cosine of the angle between two minor eigenvectors of the tidal field smoothed at the scales of $2$ and $30\,h^{-1}$Mpc centered on each of the local galaxies from the Sloan Digital Sky Data Release 10. Creating four luminosity-selected samples of the Sloan galaxies, we control them to have identical density distributions, in order to nullify the dominant effect of the local density. It is found that the samples containing more luminous wall and field galaxies yield lower mean values of the tidal coherence, which trend turns out to be robust against the variation of the smoothing scales. At fixed morphology, the same trend is found for the late-type spiral and lenticular galaxies in both of the field and wall environments. The early-type spiral field galaxies show no significant dependence on the tidal coherence, while both of the least and most luminous elliptical wall galaxies are found to dwell in the regions with highest tidal coherence.