Radio galaxy alignment in ELAIS-N1

The low noise level of below 0.02 mJy/beam of the LOFAR deep field observations at 144 MHz enabled the identification of 447 extended radio galaxies (ERG) with apparent radio size larger than 30 arcsec. For these we measured the major axis radio position angle (RPA).

For 95 per cent of these sources have either photometric or spectroscopic redshifts, we performed a three-dimensional alignment analysis. We show the distribution of the position angles of radio galaxies in the ELAIS-N1 field and perform multiple statistical tests to find that the distribution of position angles is consistent with being uniform. Two peaks around position angles of 50 and 140 deg are likely spurious and not caused by clustering of aligned sources in 3D space.