Correlating galaxy shapes and initial conditions: an observational study

TL;DR

This observational study investigates correlations between galaxy angular momenta and initial conditions using SDSS data, finding tentative signals consistent with tidal torque theory after accounting for systematic effects.

Contribution

It is the first to analyze galaxy shape correlations with initial conditions using SDSS data, highlighting potential signals predicted by tidal torque theory.

Findings

Hints of correlation in selected galaxy samples

Systematic effects influence the observed correlations

Correlations diminish below significance after corrections

Abstract

Using data from the Sloan Digital Sky Survey we study correlations between directions of galaxy angular momenta determined from images of spiral galaxies and various observables derived from the reconstructed initial conditions. We find an apparent systematic effect consistent with galaxy-orientation-dependent selection function. After restricting our attention to the brightest half of the galaxies where this systematic effect is presumed to be absent, we find hints of excess/deficit correlation for two observables. Interestingly, tidal torque theory predicts excess/deficit correlation in exactly these two observables. After correcting for the redshift space distortions, the significance of these correlations drops below 3$\sigma$ threshold. We do not find any other systematic issues, but a thorough systematic analysis goes beyond the scope of this work.