Local alignments of parsec-scale AGN radiojets

¹ Institute of Astrophysics, Foundation for Research and Technology – Hellas, Voutes, 70013 Heraklion, Greece
e-mail: nmandarakas@physics.uoc.gr
² Department of Physics, University of Crete, 70013 Heraklion, Greece
³ St. Petersburg State University, Universitetsky Pr. 28, Petrodvoretz, 198504 St. Petersburg, Russia
⁴ Max-Planck-Institut für Radioastronomie, Auf dem Hügel, 69, 53121 Bonn, Germany

Received: 9 March 2021
Accepted: 7 June 2021

Abstract

Context. Coherence in the characteristics of neighboring sources in the 2D and 3D space may suggest the existence of large-scale cosmic structures that are useful for cosmological studies. Numerous works have been conducted to detect such features in global scales as well as in confined areas of the sky. However, their results are often contradictory and their interpretation remains controversial.

Aims. We investigate the potential alignment of parsec-scale radio jets in localized regions of the coordinate-redshift space.

Methods. We used data from the Astrogeo VLBI FITS image database to deduce jet directions of radio sources. We performed the search for statistical alignments between nearby sources and explore the impact of instrumental biases.

Results. We unveil four regions for which the alignment between jet directions deviates from randomness at a significance level of more than 5σ. We find that this effect is unlikely to be due to instrumental systematics. Intriguingly, their locations coincide with other known large-scale cosmic structures or regions of alignment.

Conclusions. If the alignments found here are the result of physical processes, the discovered regions may designate some of the largest structures known to date.