The LOFAR – eFEDS survey: The incidence of radio and X-ray AGN and the disk–jet connection^⋆

¹ Max-Planck-Institut für Extraterrestrische Physik (MPE), Giessenbachstrasse 1, 85748 Garching bei München, Germany
e-mail: zigo@mpe.mpg.de
² Exzellenzcluster ORIGINS, Boltzmannstr. 2, 85748 Garching, Germany
³ Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
⁴ University of Science and Technology of China, No. 96, JinZhai Road Baohe District, Hefei, Anhui 230026, PR China
⁵ MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
⁶ ICRAR, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
⁷ School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
⁸ Istituto di Radioastronomia IRA-INAF, Via Gobetti 101, 40129 Bologna, Italy
⁹ Institute for Astronomy and Astrophysics, National Observatory of Athens, V. Paulou and I. Metaxa, Athens 11532, Greece
¹⁰ Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
¹¹ ASTRON, the Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
¹² Leiden Observatory, Leiden University, PO Box 9513 2300 RA Leiden, The Netherlands
¹³ Max-Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany

Received: 22 December 2023
Accepted: 19 February 2024

Abstract

Context. Radio jets are present in a diverse sample of AGN. However, the mechanisms of jet powering are not fully understood, and it remains unclear to what extent they obey mass-invariant scaling relations similar to those found for the triggering and fuelling of X-ray-selected AGN.

Aims. We use the multi-wavelength data in the eFEDS field observed by eROSITA/Spectrum-Roentgen-Gamma (SRG) and LOFAR to study the incidence of X-ray and radio AGN as a function of several stellar mass (M_*)-normalised AGN power indicators.

Methods. From the LOFAR – eFEDS survey, we defined a new sample of radio AGN, with optical counterparts from Legacy Survey DR9, according to a radio-excess relative to their host star formation rate. We further divided the sample into compact and complex radio morphologies. In this work, we used the subset matching to the well-characterised, highly complete spectroscopic GAMA09 galaxies (0 < z < 0.4). We release this value-added LOFAR – eFEDS catalogue^*. We calculated the fraction of GAMA09 galaxies hosting radio, X-ray, and both radio and X-ray AGN as functions of the specific black hole kinetic (λ_Jet) and radiative (λ_Edd) power.

Results. Despite the soft-X-ray eROSITA-selected sample, the incidence of X-ray AGN as a function of λ_Edd shows the same mass-invariance and power law slope (−0.65) as that found in previous studies once corrected for completeness. Across the M_* range probed, the incidence of compact radio AGN as a function of λ_Jet is described by a power law with constant slope, showing that it is not only high mass galaxies hosting high power jets and vice versa. This slope is steeper than that of the X-ray incidence, which has a value of around −1.5. Furthermore, higher-mass galaxies are more likely to host radio AGN across the λ_Jet range, indicating some residual mass dependence of jet powering. Upon adding complex radio morphologies, including 34 FRIIs, three of which are giant radio galaxies, the incidence not only shows a larger mass dependence but also a jet power dependence, being clearly boosted at high λ_Jet values. Importantly, the latter effect cannot be explained by such radio AGN residing in more dense environments (or more massive dark matter haloes). The similarity in the incidence of quiescent and star-forming radio AGN reveals that radio AGN are not only found in “red and dead” galaxies. Overall, our incidence analysis reveals some fundamental statistical properties of radio AGN samples, but highlights open questions regarding the use of a single radio luminosity–jet power conversion. We explore how different mass and accretion rate dependencies of the incidence can explain the observed results for varying disk–jet coupling models.