Link between radio-loud AGNs and host-galaxy shape

¹ Leiden Observatory, Leiden University, PO Box 9513, 2300 Leiden, RA, The Netherlands
e-mail: zheng@strw.leidenuniv.nl
² SUPA, Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
³ Sterrenkundig Observatorium, Department of Physics and Astronomy, Ghent University, Ghent, Belgium
⁴ Max-Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁵ Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
⁶ INAF – Istituto di Radioastronomia and Italian ALMA Regional Centre, Via Gobetti 101, 40129 Bologna, Italy
⁷ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁸ INAF – Istituto di Radioastronomia, Via P. Gobetti 101, 40129 Bologna, Italy

Received: 12 June 2020
Accepted: 8 October 2020

Abstract

The morphology of quiescent galaxies has been found to be correlated with the activity of their central super massive black hole. In this work, we use data from the first data release of the LOFAR Two-Metre Sky Survey (LoTSS DR1) and the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) to select more than 15 000 quiescent galaxies at z <  0.3 to investigate the connection between radio-loud active galactic nuclei (RLAGNs) and the morphology of their host galaxy. Taking advantage of the depth of LoTSS, we find that the fraction of RLAGNs with L_150 MHz > 10²¹ W Hz⁻¹ at fixed stellar mass, velocity dispersion, or surface mass density does not depend on the galaxy projected axis ratio (q). However, the high-power (L_150 MHz > 10²³ W Hz⁻¹) RLAGNs are more likely to be found in massive, round galaxies, while the low- and intermediate-power (L_150 MHz ≤ 10²³ W Hz⁻¹) RLAGNs have similar distributions of q to non-RLAGN galaxies. We argue that our results support the picture that high-power RLAGNs are more easily triggered in galaxies with a merger-rich history, while low-power RLAGNs can be triggered in galaxies growing mainly via secular processes. Our work also supports the idea that the low-luminosity RLAGN may be sufficient for maintenance-mode feedback in low-mass quiescent galaxies with disc-like morphology, which is based on a simple extrapolation from the observed energy balance between cooling and RLAGN-induced cavities in massive clusters. We find no significant difference between the q distributions of RLAGNs likely to be found in clusters and those likely not found in clusters after controlling the radio luminosity and stellar mass of the two samples, indicating that the environment does not significantly influence the morphology–RLAGN correlation.