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