The Photometric and Spectroscopic Properties of Remnant and Restarted Radio Galaxies in the Lockman Hole Field
Radio galaxies are known to undergo phases of activity, where the stage after the jets have switched off is referred to as the remnant phase. This state can be followed by a restarted phase when the activity reignites. Remnant and restarted radio sources are important for testing models of the evolu...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-12-01
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| Series: | Galaxies |
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| Online Access: | https://www.mdpi.com/2075-4434/9/4/122 |
| _version_ | 1827672320156631040 |
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| author | Nika Jurlin Raffaella Morganti Natasha Maddox Marisa Brienza |
| author_facet | Nika Jurlin Raffaella Morganti Natasha Maddox Marisa Brienza |
| author_sort | Nika Jurlin |
| collection | DOAJ |
| description | Radio galaxies are known to undergo phases of activity, where the stage after the jets have switched off is referred to as the remnant phase. This state can be followed by a restarted phase when the activity reignites. Remnant and restarted radio sources are important for testing models of the evolution of radio active galactic nuclei (AGN) and for understanding the impact the recurrent jet activity has on their host galaxies. Although we now have statistical samples of radio sources in various stages of their life cycle, how this intermittent radio activity is reflected in the optical properties in this sample has not yet been addressed, and is overall a much less studied aspect in the literature. In this work, we use the Wide-field Infrared Survey Explorer and the Sloan Digital Sky Survey (SDSS) photometry, and SDSS spectra to study these properties in a sample of the remnant, candidate restarted, and active radio galaxies selected using the LOw Frequency ARray at 150 MHz in the Lockman Hole extragalactic field. Within the range of radio luminosities and stellar masses studied in this work, we find no difference between the properties of the host galaxy and of the optical emission lines for objects in different phases of their radio life cycle. The vast majority of our radio sources (either remnant, candidate restarted, or comparison sample) are associated with radiatively inefficient optical AGN and red galaxies dominated by old stellar populations. Thus, the radio and emission-line AGN activity appears to be independent and regulated by different mechanisms. This suggests that, at least for the radio luminosities of our sample, the life cycle of the radio may depend on intrinsic reasons, such as the stability of the accretion disc, more than variation in the accretion rate and fuelling of the central black hole. |
| first_indexed | 2024-03-10T04:04:50Z |
| format | Article |
| id | doaj.art-ef6361e3862a452aa152405ba6210708 |
| institution | Directory Open Access Journal |
| issn | 2075-4434 |
| language | English |
| last_indexed | 2024-03-10T04:04:50Z |
| publishDate | 2021-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Galaxies |
| spelling | doaj.art-ef6361e3862a452aa152405ba62107082023-11-23T08:26:32ZengMDPI AGGalaxies2075-44342021-12-019412210.3390/galaxies9040122The Photometric and Spectroscopic Properties of Remnant and Restarted Radio Galaxies in the Lockman Hole FieldNika Jurlin0Raffaella Morganti1Natasha Maddox2Marisa Brienza3Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen, The NetherlandsKapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen, The NetherlandsFaculty of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 Munich, GermanyDipartimento di Fisica e Astronomia, Università di Bologna, Via P. Gobetti 93/2, I-40129 Bologna, ItalyRadio galaxies are known to undergo phases of activity, where the stage after the jets have switched off is referred to as the remnant phase. This state can be followed by a restarted phase when the activity reignites. Remnant and restarted radio sources are important for testing models of the evolution of radio active galactic nuclei (AGN) and for understanding the impact the recurrent jet activity has on their host galaxies. Although we now have statistical samples of radio sources in various stages of their life cycle, how this intermittent radio activity is reflected in the optical properties in this sample has not yet been addressed, and is overall a much less studied aspect in the literature. In this work, we use the Wide-field Infrared Survey Explorer and the Sloan Digital Sky Survey (SDSS) photometry, and SDSS spectra to study these properties in a sample of the remnant, candidate restarted, and active radio galaxies selected using the LOw Frequency ARray at 150 MHz in the Lockman Hole extragalactic field. Within the range of radio luminosities and stellar masses studied in this work, we find no difference between the properties of the host galaxy and of the optical emission lines for objects in different phases of their radio life cycle. The vast majority of our radio sources (either remnant, candidate restarted, or comparison sample) are associated with radiatively inefficient optical AGN and red galaxies dominated by old stellar populations. Thus, the radio and emission-line AGN activity appears to be independent and regulated by different mechanisms. This suggests that, at least for the radio luminosities of our sample, the life cycle of the radio may depend on intrinsic reasons, such as the stability of the accretion disc, more than variation in the accretion rate and fuelling of the central black hole.https://www.mdpi.com/2075-4434/9/4/122radio continuum: galaxiesgalaxies: active |
| spellingShingle | Nika Jurlin Raffaella Morganti Natasha Maddox Marisa Brienza The Photometric and Spectroscopic Properties of Remnant and Restarted Radio Galaxies in the Lockman Hole Field Galaxies radio continuum: galaxies galaxies: active |
| title | The Photometric and Spectroscopic Properties of Remnant and Restarted Radio Galaxies in the Lockman Hole Field |
| title_full | The Photometric and Spectroscopic Properties of Remnant and Restarted Radio Galaxies in the Lockman Hole Field |
| title_fullStr | The Photometric and Spectroscopic Properties of Remnant and Restarted Radio Galaxies in the Lockman Hole Field |
| title_full_unstemmed | The Photometric and Spectroscopic Properties of Remnant and Restarted Radio Galaxies in the Lockman Hole Field |
| title_short | The Photometric and Spectroscopic Properties of Remnant and Restarted Radio Galaxies in the Lockman Hole Field |
| title_sort | photometric and spectroscopic properties of remnant and restarted radio galaxies in the lockman hole field |
| topic | radio continuum: galaxies galaxies: active |
| url | https://www.mdpi.com/2075-4434/9/4/122 |
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