The galaxy alignment effect in Abell 1689: evolution, radial and luminosity dependence

Abstract

We measure alignments on scales of 1 Mpc $h_{71}^{-1}$ for galaxies in Abell 1689 ($z=0.18$) from an existing Hubble Space Telescope mosaic. We find evidence of galaxy alignment in the inner 500 $h_{71}^{-1}$ kpc. The alignment appears to be stronger towards the centre and is mostly present among the fainter galaxies, while bright galaxies are unaligned. This is consistent with a model where alignments originate from tidal locking.

Accepted by ApJ A few minor wording changes for clarity in the figure captions