Alignments of Radio Galaxies in Deep Radio Imaging of ELAIS N1

TL;DR

This study reveals significant large-scale alignment of radio galaxy jet orientations in the ELAIS N1 field, indicating coherent angular momentum possibly linked to cosmic structures, based on deep radio imaging data.

Contribution

First detection of large-scale spatial coherence in radio galaxy jet position angles using deep radio imaging, supporting theories of cosmic-scale angular momentum alignment.

Findings

Jet position angles align along a 1° filament

Chance alignment probability is less than 0.1%

Spatial coherence exists on scales >0.5° corresponding to >20h^{-1} Mpc at z=1

Abstract

We present a study of the distribution of radio jet position angles of radio galaxies over an area of 1 square degree in the ELAIS N1 field. ELAIS N1 was observed with the Giant Metrewave Radio Telescope at 612 MHz to an rms noise level of 10 $\mu$Jy and angular resolution of $6"\times 5"$. The image contains 65 resolved radio galaxy jets. The spatial distribution reveals a prominent alignment of jet position angles along a "filament" of about 1$^{\circ}$. We examine the possibility that the apparent alignment arises from an underlying random distribution and find that the probability of chance alignment is less than 0.1%. An angular covariance analysis of the data indicates the presence of spatially coherence in position angles on scales $>0.5^{\circ}$. This angular scales translates to a co-moving scale of $>20h^{-1}$Mpc at a redshift of 1. The implied alignment of the spin axes of massive black holes that give rise the radio jets suggest the presence of large-scale spatial coherence in angular momentum. Our results reinforce prior evidence for large-scale spatial alignments of quasar optical polarisation position angles.