Evidence for the alignment of quasar radio polarizations with large quasar group axes

Recently, evidence has been presented for the polarization vectors from quasars to preferentially align with the axes of the large
quasar groups (LQG) to which they belong. This report was based on observations made at optical wavelengths for two large quasar
groups at redshift ~1.3. The correlation suggests that the spin axes of quasars preferentially align with their surrounding large-scale
structure that is assumed to be traced by the LQGs. Here, we consider a large sample of LQGs built from the Sloan Digital Sky
Survey DR7 quasar catalogue in the redshift range 1.0 -􀀀 1.8. For quasars embedded in this sample, we collected radio polarization
measurements with the goal to study possible correlations between quasar polarization vectors and the major axis of their host LQGs.
Assuming the radio polarization vector is perpendicular to the quasar spin axis, we found that the quasar spin axis is preferentially
parallel to the LQG major axis inside LQGs that have at least 20 members. This result independently supports the observations at
optical wavelengths. We additionally found that when the richness of an LQG decreases, the quasar spin axis becomes preferentially
perpendicular to the LQG major axis and that no correlation is detected for quasar groups with fewer than 10 members.