Radio-loud AGN in the first LoTSS data release

The lifetimes and environmental impact of jet-driven sources

¹ Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, AL10 9AB UK
e-mail: m.j.hardcastle@herts.ac.uk
² SUPA, Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ UK
³ School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK
⁴ Leiden Observatory, Leiden University, PO Box 9513 2300 RA Leiden, The Netherlands
⁵ ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2 7990 AA Dwingeloo, The Netherlands
⁶ GEPI & USN, Observatoire de Paris, Université PSL, CNRS, 5 Place Jules Janssen, 92190 Meudon, France
⁷ Department of Physics & Electronics, Rhodes University, PO Box 94 Grahamstown, 6140 South Africa
⁸ Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
⁹ CSIRO Astronomy and Space Science, PO Box 1130 Bentley, WA 6102 Australia
¹⁰ Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH UK
¹¹ Physics and Astronomy Department, University of the Western Cape, Bellville, 7535 South Africa
¹² School of Physics, University College Dublin, Belfield, Dublin 4, Ireland
¹³ Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
¹⁴ INAF – Istituto di Radioastronomia, Via P. Gobetti 101, 40129 Bologna, Italy
¹⁵ Anton Pannekoek Institute for Astronomy, University of Amsterdam, Postbus 94249 1090 GE Amsterdam, The Netherlands

Received: 18 July 2018
Accepted: 22 September 2018

Abstract

We constructed a sample of 23 344 radio-loud active galactic nuclei (RLAGN) from the catalogue derived from the LOFAR Two-Metre Sky Survey (LoTSS) survey of the HETDEX Spring field. Although separating AGN from star-forming galaxies remains challenging, the combination of spectroscopic and photometric techniques we used gives us one of the largest available samples of candidate RLAGN. We used the sample, combined with recently developed analytical models, to investigate the lifetime distribution of RLAGN. We show that large or giant powerful RLAGN are probably the old tail of the general RLAGN population, but that the low-luminosity RLAGN candidates in our sample, many of which have sizes < 100 kpc, either require a very different lifetime distribution or have different jet physics from the more powerful objects. We then used analytical models to develop a method of estimating jet kinetic powers for our candidate objects and constructed a jet kinetic luminosity function based on these estimates. These values can be compared to observational quantities, such as the integrated radiative luminosity of groups and clusters, and to the predictions from models of RLAGN feedback in galaxy formation and evolution. In particular, we show that RLAGN in the local Universe are able to supply all the energy required per comoving unit volume to counterbalance X-ray radiative losses from groups and clusters and thus prevent the hot gas from cooling. Our computation of the kinetic luminosity density of local RLAGN is in good agreement with other recent observational estimates and with models of galaxy formation.