Cosmic evolution of low-excitation radio galaxies in the LOFAR Two-meter Sky Survey Deep Fields

Rohit Kondapally*, Philip N. Best, Rachel K. Cochrane, Jose Sabater, Kenneth J. Duncan, Martin J. Hardcastle, Paul Haskell, Beatriz Mingo, Huub J. A. Röttgering, Daniel J. B. Smith, Wendy L. Williams, Matteo Bonato, Gabriela Calistro Rivera, Fangyou Gao, Catherine L. Hale, Katarzyna Małek, George K. Miley, Isabella Prandoni, Lingyu Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Feedback from low-excitation radio galaxies (LERGs) plays a key role in the lifecycle of massive galaxies in the local Universe; their evolution, and the impact of these active galactic nuclei on early galaxy evolution, however, remain poorly understood. We use a sample of 10 481 LERGs from the first data release of the LOFAR Two-meter Sky Survey Deep Fields, covering ∼ 25 deg2, to present the first measurement of the evolution of the radio luminosity function (LF) of LERGs out to z ∼ 2.5; this shows relatively mild evolution. We split the LERGs into those hosted by quiescent and star-forming galaxies, finding a new dominant population of LERGs hosted by star-forming galaxies at high redshifts. The incidence of LERGs in quiescent galaxies shows a steep dependence on stellar-mass out to z ∼ 1.5, consistent with local Universe measurements of accretion occurring from cooling of hot gas haloes. The quiescent-LERGs dominate the LFs at z < 1, showing a strong decline in space density with redshift, tracing that of the available host galaxies, while there is an increase in the characteristic luminosity. The star-forming LERG LF increases with redshift, such that this population dominates the space densities at most radio-luminosities by z ∼ 1. The incidence of LERGs in star-forming galaxies shows a much weaker stellar-mass dependence, and increases with redshift, suggesting a different fuelling mechanism compared to their quiescent counterparts, potentially associated with the cold gas supply present in the star-forming galaxies.
Original languageEnglish
Pages (from-to)3742-767
Number of pages26
JournalMonthly Notices of the Royal Astronomical Society
Volume513
Issue number3
Early online date26 Apr 2022
DOIs
Publication statusPublished - 1 Jul 2022

Keywords

  • astro-ph.GA
  • astro-ph.HE

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