LeMMINGs III. The e-MERLIN legacy survey of the Palomar sample: Exploring the origin of nuclear radio emission in active and inactive galaxies through the [O iii] - Radio connection

R. D. Baldi, D. R.A. Williams, R. J. Beswick, I. Mchardy, B. T. Dullo, J. H. Knapen, L. Zanisi, M. K. Argo, S. Aalto, A. Alberdi, W. A. Baan, G. J. Bendo, D. M. Fenech, D. A. Green, H. R. Klöckner, E. Körding, T. J. Maccarone, J. M. Marcaide, I. Mutie, F. PanessaM. A. Pérez-Torres, C. Romero-Cañizales, D. J. Saikia, P. Saikia, F. Shankar, R. E. Spencer, I. R. Stevens, P. Uttley, E. Brinks, S. Corbel, I. Martí-Vidal, C. G. Mundell, M. Pahari, M. J. Ward

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15 Citations (SciVal)


What determines the nuclear radio emission in local galaxies? To address this question, we combine optical [O iii] line emission, robust black hole (BH) mass estimates, and high-resolution e-MERLIN 1.5-GHz data, from the LeMMINGs survey, of a statistically complete sample of 280 nearby optically active (LINER and Seyfert) and inactive [H ii and absorption line galaxies (ALGs)] galaxies. Using [O iii] luminosity (L[O III]) as a proxy for the accretion power, local galaxies follow distinct sequences in the optical-radio planes of BH activity, which suggest different origins of the nuclear radio emission for the optical classes. The 1.5-GHz radio luminosity of their parsec-scale cores (Lcore) is found to scale with BH mass (MBH) and [O iii] luminosity. Below MBH ∼106.5 M⊙, stellar processes from non-jetted H ii galaxies dominate with Lcore ∝ MBH0.61 ± 0.33 and Lcore ∝ L[O III]0.79 ± 0.30. Above MBH ∼106.5 M⊙, accretion-driven processes dominate with Lcore ∝ MBH1.5-1.65 and Lcore ∝ L[O III]0.99-1.31 for active galaxies: radio-quiet/loud LINERs, Seyferts, and jetted H ii galaxies always display (although low) signatures of radio-emitting BH activity, with L1.5 GHz ≳ 1019.8 W Hz-1 and MBH ≳ 107 M⊙, on a broad range of Eddington-scaled accretion rates (m). Radio-quiet and radio-loud LINERs are powered by low-m discs launching sub-relativistic and relativistic jets, respectively. Low-power slow jets and disc/corona winds from moderately high to high-m discs account for the compact and edge-brightened jets of Seyferts, respectively. Jetted H ii galaxies may host weakly active BHs. Fuel-starved BHs and recurrent activity account for ALG properties. In conclusion, specific accretion-ejection states of active BHs determine the radio production and the optical classification of local active galaxies.

Original languageEnglish
Pages (from-to)2019-2038
Number of pages20
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 15 Oct 2021

Bibliographical note

Funding Information:
We thank the referee for his or her comments, which helped to improve the paper. This research was supported by a Newton Fund project, DARA (Development in Africa with Radio Astronomy), and awarded by the UK's Science and Technology Facilities Council (STFC). grant reference ST/R001103/1. This research was supported by European Commission Horizon 2020 Research and Innovation Programme under grant agreement No. 730884 (JUMPING JIVE). FS acknowledges support from a Leverhulme Trust Research Fellowship. JHK acknowledges support from the European Union's Horizon 2020 research and innovation programme under Marie Sk.odowska-Curie grant agreement no. 721463 to the SUNDIAL ITN network, from the State Research Agency (AEI) of the Spanish Ministry of Science and Innovation and the European Regional Development Fund (FEDER) under the grant with reference PID2019-105602GB-I00, and from IAC project P/300724, financed by the Ministry of Science and Innovation, through the State Budget and by the Canary Islands Department of Economy, Knowledge and Employment, through the Regional Budget of the Autonomous Community. IMV thanks the Generalitat Valenciana (funding from the GenT Project CIDEGENT/2018/021) and the MICINN (funding from the Research Project PID2019-108995GBC22). AA and MAPT acknowledge support from the SpanishMCIU through grant PGC2018-098915-B-C21 and from the State Agency for Research of the SpanishMCIU through the 'Center of Excellence Severo Ochoa' award for the Instituto de Astrofsica de Andaluca (SEV-2017-0709). BTD acknowledges financial support from grant 'Ayudas para la realizacion de proyectos de I + D para jovenes doctores 2019' funded by Comunidad de Madrid and Universidad Complutense de Madrid under grant no. PR65/19-22417.

Publisher Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.


  • galaxies: active
  • galaxies: jets
  • galaxies: nuclei
  • galaxies: star formation
  • radio continuum: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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