The LOFAR Two-metre Sky Survey

Duncan, K. J.; Sabater, J.; Röttgering, H. J. A.; Jarvis, Matt J.; Smith, D. J. B.; Best, P. N.; Callingham, J. R.; Cochrane, R. K.; Croston, J. H.; Hardcastle, M. J.; Mingo, B.; Morabito, L. K.; Nisbet, D.; Prandoni, I.; Shimwell, T. W.; Tasse, C.; White, G. J.; Williams, W. L.; Alegre, L.; Chyży, K. T.; Gürkan, G.; Hoeft, M.; Kondapally, R.; Mechev, A. P.; Miley, G. K.; Schwarz, Dominik J.; Weeren, R. J. van

doi:10.1051/0004-6361/201833562

Cited by 73 publications

(73 citation statements)

References 48 publications

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“…LoTSS-DR1 contains 318,520 sources over 424 deg 2 of the northern sky. Of the LoTSS sources, 73 per cent have optical identifications (Williams et al 2019) and 51 per cent have either spectroscopic or photometric redshifts (Duncan et al 2019). Our aim is to investigate the population of radio-loud AGN within this catalogue, so we restrict our analysis to the radio-loud AGN sample of Hardcastle et al (2019), which contains 23,344 sources.…”

Section: The Lotss Datasetsmentioning

confidence: 99%

“…• Less reliable host identifications, particularly for more distant sources (Duncan et al 2019;Williams et al 2019) -∼ 5 per cent of FRIs and FRIIs. Table 3.…”

Section: D2=0 1_sided=1mentioning

confidence: 99%

“…The ratio between FRIs and FRIIs is very different for these sources, which is expected because of the evolution of the FRIIs and/or HERG luminosity function to higher redshift, and the fact that unambiguous FRIIs can be identified at smaller angular sizes due to their brightness distribution. As mentioned in Section 2.2, we do not analyse sources without an identified optical host, which are likely to lie at even higher redshift (Duncan et al 2019), but similar selection effects likely apply. We note therefore that our sample is not "representative" of the FRI/FRII mix in the full LoTSS catalogue.…”

Section: Redshift Distributions and Selection Effectsmentioning

confidence: 99%

“…In the top panel of Fig. 10 we compare the distribution of host-galaxy rest-frame K s band magnitudes (M K s , Duncan et al 2019) of the FRII-Low with the FRII-High subsample (see above), restricting the sample to the range of physical and angular sizes occupied by both populations. It is apparent that the host-galaxy magnitudes are significantly different for the two subsamples: FRII-Low sources inhabit systematically lower luminosity host galaxies.…”

Section: The Nature Of the Low-luminosity Friis In Lotssmentioning

confidence: 99%

“…11 shows the relationship between morphology, radio luminosity and host-galaxy magnitude for the z < 0.8 FRI and FRII samples. We use the hostgalaxy rest-frame K s magnitudes (M K s , Duncan et al 2019), as a proxy of overall stellar mass (see e.g. Bell et al 2003;Caputi et al 2005;Arnouts et al 2007;Konishi et al 2011).…”

Section: Testing the Jet Disruption Model: Host-galaxy Dependence Of mentioning

confidence: 99%

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Revisiting the Fanaroff–Riley dichotomy and radio-galaxy morphology with the LOFAR Two-Metre Sky Survey (LoTSS)

Mingo

Croston

Hardcastle

et al. 2019

Monthly Notices of the Royal Astronomical Society

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190

223

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Abstract The relative positions of the high and low surface brightness regions of radio-loud active galaxies in the 3CR sample were found by Fanaroff and Riley to be correlated with their luminosity. We revisit this canonical relationship with a sample of 5805 extended radio-loud active galactic nuclei (AGN) from the LOFAR Two-Metre Sky Survey (LoTSS), compiling the most complete data set of radio-galaxy morphological information obtained to date. We demonstrate that, for this sample, radio luminosity does not reliably predict whether a source is edge-brightened (FRII) or centre-brightened (FRI). We highlight a large population of low-luminosity FRIIs, extending three orders of magnitude below the traditional FR break, and demonstrate that their host galaxies are on average systematically fainter than those of high-luminosity FRIIs and of FRIs matched in luminosity. This result supports the jet power/environment paradigm for the FR break: low-power jets may remain undisrupted and form hotspots in lower mass hosts. We also find substantial populations that appear physically distinct from the traditional FR classes, including candidate restarting sources and ‘hybrids’. We identify 459 bent-tailed sources, which we find to have a significantly higher SDSS cluster association fraction (at z < 0.4) than the general radio-galaxy population, similar to the results of previous work. The complexity of the LoTSS faint, extended radio sources not only demonstrates the need for caution in the automated classification and interpretation of extended sources in modern radio surveys, but also reveals the wealth of morphological information such surveys will provide and its value for advancing our physical understanding of radio-loud AGN.

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Section: The Lotss Datasetsmentioning

confidence: 99%

“…• Less reliable host identifications, particularly for more distant sources (Duncan et al 2019;Williams et al 2019) -∼ 5 per cent of FRIs and FRIIs. Table 3.…”

Section: D2=0 1_sided=1mentioning

confidence: 99%

Section: Redshift Distributions and Selection Effectsmentioning

confidence: 99%

Section: The Nature Of the Low-luminosity Friis In Lotssmentioning

confidence: 99%

Section: Testing the Jet Disruption Model: Host-galaxy Dependence Of mentioning

confidence: 99%

See 3 more Smart Citations

Revisiting the Fanaroff–Riley dichotomy and radio-galaxy morphology with the LOFAR Two-Metre Sky Survey (LoTSS)

Mingo

Croston

Hardcastle

et al. 2019

Monthly Notices of the Royal Astronomical Society

Self Cite

190

223

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Measuring photometric redshifts for high-redshift radio source surveys

Luken

Norris

Wang

et al. 2023

Publ. Astron. Soc. Aust.

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With the advent of deep, all-sky radio surveys, the need for ancillary data to make the most of the new, high-quality radio data from surveys like the Evolutionary Map of the Universe (EMU), GaLactic and Extragalactic All-sky MurchisonWidefield Array survey eXtended, Very Large Array Sky Survey and LOFAR Two-metre Sky Survey is growing rapidly. Radio surveys produce significant numbers of Active Galactic Nuclei (AGNs), and have a significantly higher average redshift when compared with optical and infrared all-sky surveys. Thus, traditional methods of estimating redshift are challenged, with spectroscopic surveys not reaching the redshift depth of radio surveys, and AGNs making it difficult for template fitting methods to accurately model the source. Machine Learning (ML) methods have been used, but efforts have typically been directed towards optically selected samples, or samples at significantly lower redshift than expected from upcoming radio surveys. This work compiles and homogenises a radio-selected dataset from both the northern hemisphere (making use of Sloan Digital Sky Survey optical photometry), and southern hemisphere (making use of Dark Energy Survey optical photometry). We then test commonly used ML algorithms such as k-Nearest Neighbours (kNN), Random Forest, ANNz and GPz on this monolithic radio-selected sample. We show that kNN has the lowest percentage of catastrophic outliers, providing the best match for the majority of science cases in the EMU survey. We note that the wider redshift range of the combined dataset used allows for estimation of sources up to z = 3 before random scatter begins to dominate. When binning the data into redshift bins and treating the problem as a classification problem, we are able to correctly identify ≈76% of the highest redshift sources — sources at redshift z > 2.51 — as being in either the highest bin (z > 2.51), or second highest (z = 2.25).

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Life-cycles & Energetics of Radio-Loud AGN

Mahatma

Hardcastle

team³

2018

Proc. IAU

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Radio jets are the large-scale and extragalactic footprints of accretion onto supermassive black holes, and are suggested to be the key ingredient controlling the galaxy stellar mass function. Of particular importance is their jet power - the time-averaged energetic feedback into their environment. Hence, the dynamics, energetics and life-cycles of radio-loud AGN (RLAGN) must be understood in order to build a qualitative and quantitative picture of their impact over cosmic time. Here, we present a study of the spectral age of two powerful, cluster-center radio galaxies, and compare with an analytic model to robustly determine their jet powers. We also present some recent LOFAR observations of the different phases of RLAGN activity, namely the remnant and subsequent restarting phases, which are key to understanding the dynamics of RLAGN over their total lifetime.

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The LOFAR Two-metre Sky Survey

Cited by 73 publications

References 48 publications

Revisiting the Fanaroff–Riley dichotomy and radio-galaxy morphology with the LOFAR Two-Metre Sky Survey (LoTSS)

Revisiting the Fanaroff–Riley dichotomy and radio-galaxy morphology with the LOFAR Two-Metre Sky Survey (LoTSS)

Measuring photometric redshifts for high-redshift radio source surveys

Life-cycles & Energetics of Radio-Loud AGN

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