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The life cycle of radio galaxies in the LOFAR Lockman Hole field


Jurlin, N and Morganti, R and Brienza, M and Mandal, S and Maddox, N and Duncan, KJ and Shabala, SS and Hardcastle, MJ and Prandoni, I and Rottgering, HJA and Mahatma, V and Best, PN and Mingo, B and Sabater, J and Shimwell, TW and Tasse, C, The life cycle of radio galaxies in the LOFAR Lockman Hole field, Astronomy and Astrophysics, 638 Article A34. ISSN 0004-6361 (2020) [Refereed Article]

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Copyright ESO 2020

DOI: doi:10.1051/0004-6361/201936955


Radio galaxies are known to go through cycles of activity, where phases of apparent quiescence can be followed by repeated activity of the central supermassive black hole. A better understanding of this cycle is crucial for ascertaining the energetic impact that the jets have on the host galaxy, but little is known about it. We used deep LOFAR images at 150 MHz of the Lockman Hole extragalactic field to select a sample of 158 radio sources with sizes > 60″ in different phases of their jet life cycle. Using a variety of criteria (e.g. core prominence combined with low-surface brightness of the extended emission and steep spectrum of the central region) we selected a subsample of candidate restarted radio galaxies representing between 13% and 15% of the 158 sources of the main sample. We compare their properties to the rest of the sample, which consists of remnant candidates and active radio galaxies. Optical identifications and characterisations of the host galaxies indicate similar properties for candidate restarted, remnant, and active radio galaxies, suggesting that they all come from the same parent population. The fraction of restarted radio galaxies is slightly higher with respect to remnants, suggesting that the restarted phase can often follow after a relatively short remnant phase (the duration of the remnant phase being a few times 107 years). This confirms that the remnant and restarted phases are integral parts of the life cycle of massive elliptical galaxies. A preliminary investigation does not suggest a strong dependence of this cycle on the environment surrounding any given galaxy.

Item Details

Item Type:Refereed Article
Keywords:surveys - radio continuum: galaxies - galaxies: active
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Cosmology and extragalactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Shabala, SS (Associate Professor Stas Shabala)
ID Code:138355
Year Published:2020
Web of Science® Times Cited:21
Deposited By:Physics
Deposited On:2020-04-02
Last Modified:2020-08-31
Downloads:20 View Download Statistics

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