Combining LOFAR and Apertif Data for Understanding the Life Cycle of Radio Galaxies

Active galactic nuclei (AGN) at the centres of galaxies can cycle between periods of activity and of quiescence. Characterising the duty-cycle of AGN is crucial for understanding their impact on the evolution of the host galaxy. For radio AGN, their evolutionary stage can be identified from a combination of morphological and spectral properties. We summarise the results we have obtained in the last few years by studying radio galaxies in various crucial phases of their lives, such as remnant and restarted sources. We used morphological information derived from LOw Frequency ARray (LOFAR) images at 150 MHz, combined with resolved spectral indices maps, obtained using recently released images at 1400 MHz from the APERture Tile In Focus (Apertif) phased-array feed system installed on the Westerbork Synthesis Radio Telescope. Our study, limited so far to the Lockman Hole region, has identified radio galaxies in the dying and restarted phases. We found large varieties in their properties, relevant for understanding their evolutionary stage. We started by quantifying their occurrences, the duration of the ‘on’ (active) and ‘off’ (dying) phase, and we compared the results with models of the evolution of radio galaxies. In addition to these extreme phases, the resolved spectral index images can also reveal interesting secrets about the evolution of apparently normal radio galaxies. The spectral information can be connected with, and used to improve, the Fanaroff–Riley classification, and we present one example of this, illustrating what the combination of the LOFAR and Apertif surveys now allow us to do routinely.

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Luminosity Correlation of the X-ray Selected Radio-Loud AGNs

Symposium - International Astronomical Union ◽

10.1017/s0074180900162151 ◽

1999 ◽

Vol 194 ◽

pp. 306-310

Author(s):

Q. Yuan ◽

J. Wu ◽

K. Huang

Keyword(s):

Active Galactic Nuclei ◽

Broad Band ◽

Galactic Nuclei ◽

Radio Galaxies ◽

Spectral Indices ◽

Strong Correlations ◽

Band Energy ◽

X Ray ◽

Sky Survey ◽

Bl Lacs

This paper presents a test of the luminosity correlation of the X-ray selected radio-loud Active Galactic Nuclei (AGNs), based on a large sample constructed by combining our cross-identification of southern sky sources with the radio-loud sources in the northern hemisphere given by Brinkmann et al. (1995). All sources were detected both by the ROSAT All-Sky Survey and the radio surveys at 4.85 GHz. The broad band energy distribution confirms the presence of strong correlations between luminosities in the radio, optical, and X-ray bands which differ for quasars, seyferts, BL Lacs, and radio galaxies. The tight correlations between spectral indices αox and monochromatic luminosities at 5500 Å and 4.85 GHz are also shown.

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The duty cycle of radio galaxies revealed by LOFAR: remnant and restarted radio source populations in the Lockman Hole

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1172 ◽

2020 ◽

Vol 496 (2) ◽

pp. 1706-1717 ◽

Cited By ~ 2

Author(s):

Stanislav S Shabala ◽

Nika Jurlin ◽

Raffaella Morganti ◽

Marisa Brienza ◽

Martin J Hardcastle ◽

...

Keyword(s):

Active Galactic Nuclei ◽

Radio Source ◽

Low Frequency ◽

Galactic Nuclei ◽

Radio Jets ◽

Modelling Analysis ◽

Self Consistent ◽

Large Populations ◽

Source Populations ◽

Lockman Hole

ABSTRACT Feedback from radio jets associated with active galactic nuclei (AGNs) plays a profound role in the evolution of galaxies. Kinetic power of these radio jets appears to show temporal variation, but the mechanism(s) responsible for this process are not yet clear. Recently, the LOw Frequency ARray (LOFAR) has uncovered large populations of active, remnant, and restarted radio jet populations. By focusing on LOFAR data in the Lockman Hole, in this work we use the Radio AGNs in Semi-Analytic Environments (RAiSE) dynamical model to present the first self-consistent modelling analysis of active, remnant, and restarted radio source populations. Consistent with other recent work, our models predict that remnant radio lobes fade quickly. Any high (>10 per cent) observed fraction of remnant and restarted sources therefore requires a dominant population of short-lived jets. We speculate that this could plausibly be provided by feedback-regulated accretion.

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Feeding and feedback in nuclei of galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002239 ◽

2020 ◽

Vol 15 (S359) ◽

pp. 307-311

Author(s):

Anelise Audibert ◽

Françoise Combes ◽

Santiago García-Burillo ◽

Kalliopi Dasyra

Keyword(s):

High Resolution ◽

Active Galactic Nuclei ◽

Galaxy Evolution ◽

Galactic Nuclei ◽

Radio Galaxies ◽

Host Galaxy ◽

Molecular Gas ◽

Molecular Outflows ◽

Radio Jets ◽

The Impact

AbstractOur aim is to explore the close environment of Active Galactic Nuclei (AGN) and its connection to the host galaxy through the morphology and dynamics of the cold gas inside the central kpc in nearby AGN. We report Atacama Large Millimeter/submillimeter Array (ALMA) observations of AGN feeding and feedback caught in action in NGC613 and NGC1808 at high resolution (few pc), part of the NUclei of GAlaxies (NUGA) project. We detected trailing spirals inside the central 100 pc, efficiently driving the molecular gas into the SMBH, and molecular outflows driven by the AGN. We present preliminary results of the impact of massive winds induced by radio jets on galaxy evolution, based on observations of radio galaxies from the ALMA Radio-source Catalogue.

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The Photometric and Spectroscopic Properties of Remnant and Restarted Radio Galaxies in the Lockman Hole Field

Galaxies ◽

10.3390/galaxies9040122 ◽

2021 ◽

Vol 9 (4) ◽

pp. 122

Author(s):

Nika Jurlin ◽

Raffaella Morganti ◽

Natasha Maddox ◽

Marisa Brienza

Keyword(s):

Life Cycle ◽

Low Frequency ◽

Optical Emission ◽

Spectroscopic Properties ◽

Radio Galaxies ◽

Host Galaxy ◽

Radio Sources ◽

Wide Field ◽

The Impact ◽

Lockman Hole

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.

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LoTSS DR1: Double-double radio galaxies in the HETDEX field

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833973 ◽

2019 ◽

Vol 622 ◽

pp. A13 ◽

Cited By ~ 13

Author(s):

V. H. Mahatma ◽

M. J. Hardcastle ◽

W. L. Williams ◽

P. N. Best ◽

J. H. Croston ◽

...

Keyword(s):

Life Cycle ◽

Active Galactic Nuclei ◽

Galaxy Evolution ◽

Control Sample ◽

Galactic Nuclei ◽

Radio Galaxies ◽

Host Galaxy ◽

Host Galaxies ◽

Significant Difference ◽

Double Radio Galaxies

Context. Double-double radio galaxies (DDRGs) represent a short but unique phase in the life-cycle of some of the most powerful radio-loud active galactic nuclei (RLAGN). These galaxies display large-scale remnant radio plasma in the intergalactic medium left behind by a past episode of active galactic nuclei (AGN) activity, and meanwhile, the radio jets have restarted in a new episode. The knowledge of what causes the jets to switch off and restart is crucial to our understanding of galaxy evolution, while it is important to know if DDRGs form a host galaxy dichotomy relative to RLAGN. Aims. The sensitivity and field of view of LOFAR enables the observation of DDRGs on a population basis rather than single-source observations. Using statistical comparisons with a control sample of RLAGN, we may obtain insights into the nature of DDRGs in the context of their host galaxies, where physical differences in their hosts compared to RLAGN as a population may allow us to infer the conditions that drive restarting jets. Methods. We utilised the LOFAR Two-Metre Sky Survey (LoTSS) DR1, using a visual identification method to compile a sample of morphologically selected candidate DDRGs, showing two pairs of radio lobes. To confirm the restarted nature in each of the candidate sources, we obtained follow-up observations with the Karl. G. Jansky Very Large Array (VLA) at higher resolution to observe the inner lobes or restarted jets, the confirmation of which created a robust sample of 33 DDRGs. We created a comparison sample of 777 RLAGN, matching the luminosity distribution of the DDRG sample, and compared the optical and infrared magnitudes and colours of their host galaxies. Results. We find that there is no statistically significant difference in the brightness of the host galaxies between double-doubles and single-cycle RLAGN. The DDRG and RLAGN samples also have similar distributions in WISE mid-infrared colours, indicating similar ages of stellar populations and dust levels in the hosts of DDRGs. We conclude that DDRGs and “normal” RLAGN are hosted by galaxies of the same type, and that DDRG activity is simply a normal part of the life cycle of RLAGN. Restarted jets, particularly for the class of low-excitation radio galaxies, rather than being a product of a particular event in the life of a host galaxy, must instead be caused by smaller scale changes, such as in the accretion system surrounding the black hole.

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Jet-Induced Feedback in the [O III] Lines of Early Evolution Stage Active Galactic Nuclei

Universe ◽

10.3390/universe7060188 ◽

2021 ◽

Vol 7 (6) ◽

pp. 188

Author(s):

Marco Berton ◽

Emilia Järvelä

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Plasma Jets ◽

Early Evolution ◽

Host Galaxy ◽

Bolometric Luminosity ◽

Radio Imaging ◽

Strong Relation ◽

Evolution Stage ◽

Good Proxy

It is well known that active galactic nuclei (AGN) show various forms of interaction with their host galaxy, in a number of phenomena generally called AGN feedback. In particular, the relativistic plasma jets launched by a fraction of AGN can strongly affect their environment. We present here a study of the [O III] λλ4959,5007 lines in a diverse sample of early evolution stage AGN–specifically narrow-line Seyfert 1 galaxies. Radio imaging observations of all of the sources enable a division to jetted and non-jetted sources, and exploiting this we show that the ionized gas properties are significantly influenced by the presence of the jets, as we often find the [O III] lines (blue-)shifted with respect to their restframe wavelength. We also show how the radio morphology and the radio spectral index do not seem to play a role in the origin of the [O III] shifts, thus suggesting that the source inclination is not relevant to the lines displacement. We do not find a strong relation between the [O III] line properties and the bolometric luminosity, suggesting that within our sample radiatively driven outflows do not seem to have a significant contribution to the [O III] line kinematics. We finally suggest that [O III] shifts may be a good proxy to identify the presence of relativistic jets. Additional studies, especially with integral-field spectroscopy, will provide a deeper insight into the relation between jets and their environment in early evolution stage AGN.

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The GLEAM 4-Jy Sample: The brightest radio-sources in the southern sky

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320003476 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 375-375

Author(s):

Sarah White

Keyword(s):

Radio Emission ◽

Active Galactic Nuclei ◽

Visual Inspection ◽

Low Frequency ◽

Galactic Nuclei ◽

Radio Sources ◽

Relativistic Jets ◽

The Galaxy ◽

Murchison Widefield Array ◽

Past Activity

AbstractLow-frequency radio emission allows powerful active galactic nuclei (AGN) to be selected in a way that is unaffected by dust obscuration and orientation of the jet axis. It also reveals past activity (e.g. radio lobes) that may not be evident at higher frequencies. Currently, there are too few “radio-loud” galaxies for robust studies in terms of redshift-evolution and/or environment. Hence our use of new observations from the Murchison Widefield Array (the SKA-Low precursor), over the southern sky, to construct the GLEAM 4-Jy Sample (1,860 sources at S151MHz > 4 Jy). This sample is dominated by AGN and is 10 times larger than the heavily relied-upon 3CRR sample (173 sources at S178MHz > 10 Jy) of the northern hemisphere. In order to understand how AGN influence their surroundings and the way galaxies evolve, we first need to correctly identify the galaxy hosting the radio emission. This has now been completed for the GLEAM 4-Jy Sample – through repeated visual inspection and extensive checks against the literature – forming a valuable, legacy dataset for investigating relativistic jets and their interplay with the environment.

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Subtraction of Bright Point Sources from Synthesis Images of the Epoch of Reionization

Publications of the Astronomical Society of Australia ◽

10.1071/as10023 ◽

2011 ◽

Vol 28 (1) ◽

pp. 46-57 ◽

Cited By ~ 23

Author(s):

B. Pindor ◽

J. S. B. Wyithe ◽

D. A. Mitchell ◽

S. M. Ord ◽

R. B. Wayth ◽

...

Keyword(s):

Active Galactic Nuclei ◽

Dynamic Range ◽

Low Frequency ◽

Neutral Hydrogen ◽

Galactic Nuclei ◽

Point Sources ◽

Field Of View ◽

Bright Point ◽

Line Of Sight ◽

Diffuse Background

AbstractBright point sources associated with extragalactic active galactic nuclei and radio galaxies are an important foreground for low-frequency radio experiments aimed at detecting the redshifted 21-cm emission from neutral hydrogen during the epoch of reionization. The frequency dependence of the synthesized beam implies that the sidelobes of these sources will move across the field of view as a function of observing frequency, hence frustrating line-of-sight foreground subtraction techniques. We describe a method for subtracting these point sources from dirty maps produced by an instrument such as the MWA. This technique combines matched filters with an iterative centroiding scheme to locate and characterize point sources in the presence of a diffuse background. Simulations show that this technique can improve the dynamic range of epoch-of-reionization maps by 2—3 orders of magnitude.

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