The relations between radio and forbidden [O III]-emission line luminosities in FRII radiogalaxies

Rawlings, Steve; Saunders, Richard D. E.; Eales, Stephen Anthony; Mackay, Craig D.

doi:10.1093/mnras/240.3.701

Cited by 75 publications

(66 citation statements)

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“…A correlation between emission lines and core radio powers, although weaker than that observed for L radio and L line , is also found (e.g. Baum & Heckman 1989b;Rawlings et al 1989;Rawlings & Saunders 1991) suggesting that the total radio luminosity is separately correlated with the [O III] and the core radio power. Morganti et al (1992) extended the line-radio connection towards lower radio luminosities considering sources from the B2 sample, predominantly FR I, noting a flattening in the correlation.…”

Section: O Iii]/[o Ii] Line Ratiomentioning

confidence: 82%

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An optical spectroscopic survey of the 3CR sample of radio galaxies withz$\mathsf{<}$ 0.3

Buttiglione¹,

Capetti

Celotti³

et al. 2010

A&A

255

390

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In a previous paper we presented a homogeneous and 92% complete optical spectral dataset of the 3CR radio sources with redshift <0.3. Here we use the emission line measurements to explore the spectroscopic properties of the sample. The 3CR sources show a bimodal distribution of excitation index, a new spectroscopic indicator that measures the relative intensity of low and high excitation lines. This unveils the presence of two main sub-populations of radio-loud AGN to which we refer to, following previous studies, as high and low excitation galaxies (HEG and LEG, respectively). In addition to the two main classes, we find one source with a spectrum typical of star forming galaxies, and 3 objects of extremely low level of excitation. All broad-line objects are HEG from the point of view of their narrow emission line ratios and all HEG are FR II radio-galaxies with log L 178 [erg s −1 ] > ∼ 32.8. Conversely LEG cover the whole range of radio power encompassed by this 3CR subsample (30.7 < ∼ log L 178 < ∼ 35.4) and they are of both FR I and FR II type. The brightest LEG are all FR II. HEG and LEG obey to two (quasi) linear correlations between the optical line and extended radio luminosities, with HEG being brighter than LEG in the [O III] line by a factor of ∼10. HEG and LEG are offset also in a plane that compares the black hole mass and the ionizing nuclear luminosity. However, although HEG are associated with higher nuclear luminosities, we find LEG among the brightest radio sources of the sample and with a clear FR II morphology, indistinguishable from those seen in HEG. This suggests that LEG are not simply objects with a lower level of accretion. We speculate that the differences between LEG and HEG are related to a different mode of accretion: LEG are powered by hot gas, while HEG require the presence of cold accreting material. The high temperature of the accreting gas in LEG accounts for the lack of "cold" structures (i.e. molecular torus and broad line region), for the reduced radiative output of the accretion disk, and for the lower gas excitation.

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Section: O Iii]/[o Ii] Line Ratiomentioning

confidence: 82%

“…Baum & Heckman 1989a,b;Rawlings et al 1989;Rawlings & Saunders 1991). This relation holds also for compact steep spectrum (CSS) (Morganti et al 1997) and GHz peaked spectrum (GPS) sources (Labiano 2008).…”

Section: O Iii]/[o Ii] Line Ratiomentioning

confidence: 87%

An optical spectroscopic survey of the 3CR sample of radio galaxies withz$\mathsf{<}$ 0.3

Buttiglione¹,

Capetti

Celotti³

et al. 2010

A&A

255

390

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show abstract

“…Conversely, the well established correlation between total radio and line luminosities (e.g. Baum & Heckman 1989;Rawlings et al 1989;Rawlings & Saunders 1991) is likely to be the result of the selection of radio sources of similar range of core dominance, imposed by the selection criteria of the sample.…”

Section: Discussionmentioning

confidence: 99%

Radio and spectroscopic properties of miniature radio galaxies: revealing the bulk of the radio-loud AGN population

Baldi¹,

Capetti²

2009

A&A

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We explore radio and spectroscopic properties of a sample of 14 miniature radio galaxies, i.e. early-type core galaxies hosting radioloud AGN of extremely low radio power, 10 27−29 erg s −1 Hz −1 at 1.4 GHz. Miniature radio galaxies smoothly extend the relationships found for the more powerful FR I radio galaxies between emission line, optical and radio nuclear luminosities to lower levels. However, they have a deficit of a factor of ∼100 in extended radio emission with respect to that of the classical example of 3CR/FR I. This is not due to their low luminosity, since we found radio galaxies of higher radio core power, similar to those of 3CR/FR I, showing the same behavior, i.e. lacking significant extended radio emission. Such sources form the bulk of the population of radio-loud AGN in the Sloan Digital Sky Survey. At a given level of nuclear emission, one can find radio sources with an extremely wide range, a factor of > ∼ 100, of radio power. We argue that the prevalence of sources with luminous extended radio structures in flux limited samples is due to a selection bias, since the inclusion of such objects is highly favored. The most studied catalogues of radio galaxies are thus composed by the minority of radio-loud AGN that meet the physical conditions required to form extended radio sources, while the bulk of the population is virtually unexplored.

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“…L 20 cm − L o relation, where L o is the luminosity in the optical) because they come from the same physical process. Strong emission lines, such as [Oiii]λ5007, [Oii]λ3727, and Hβ, are indeed believed to come from powerful radio emitters (Baum & Heckman 1989;Rawlings et al 1989;Rawlings & Saunders 1991;Morganti et al 1992;Tadhunter et al 1998;Best & Heckman 2012). …”

Section: Diagnostic Diagrams For the Cross-matched Samplementioning

confidence: 99%

Classifying radio emitters from the Sloan Digital Sky Survey

Vitale

Zuther

García-Marín

et al. 2012

A&A

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Context. The Sloan Digital Sky Survey (SDSS) allows us to classify galaxies using optical low-ionization emission-line diagnostic diagrams. A cross-correlation of the SDSS data release 7 (DR7), containing spectroscopic data, with the Very Large Array (VLA) survey Faint Images of the Radio Sky at Twenty-centimeters (FIRST), makes it possible to conduct a joined multiwavelength statistical study of radio-optical galaxy properties on a very large number of sources. Aims. Our goal is to improve the study of the combined radio-optical data by investigating whether there is a correlation between the radio luminosity at 20 cm over the luminosity of the optical Hα line (L 20 cm /L Hα ) and line excitation ratios, where the latter provide the spectroscopic classification in Seyferts, low-ionization nuclear emission-line regions (LINERs), and star-forming galaxies. We search for a trend with z in the classification provided by classical and more recent optical emission-line diagnostic diagrams. Methods. We cross-matched the optical sources with the FIRST radio survey in order to obtain spectroscopic information of a selected sample of radio emitters with optical observed counterpart. We searched for an L 20 cm /L Hα threshold value above which the radio emitters start being classified as active galactic nuclei (AGNs) rather than star-forming galaxies (SFGs). We investigated the origin of emission-lines by using both photoionization and shock models. Results. The percentage of detected AGNs (Seyferts and LINERs) or composites is much higher in the optical-radio sample than in the optical sample alone. We find a progressive shift in the sources towards the AGN region of the diagram with increasing L 20 cm /L Hα , with an indication of different behavior for LINERs and Seyferts. The classification appears to slightly depend on the redshift. The diagnostic diagrams display a density peak in the star-forming or composite region for log (L 20 cm /L Hα ) < 0.716, while the distribution in the LINER region peaks above this threshold. A comparison with photoionization and shock models shows that the large fraction of LINERs identified in our study have emission lines that may be explained by shocks. Conclusions. Our results indicate that it is worthwhile to further explore the radio domain, probing the physical nature of LINERs, thanks to a combination of optical and radio information. The [Nii]/Hα vs. equivalent width of the Hα line (WHAN) diagram confirms the LINER classification for most of those that have been identified with the traditional diagnostic diagrams. The correlation between L 20 cm /L Hα and optical emission line ratios suggests the nuclear origin of the emission from the most powerful radio galaxies.

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The relations between radio and forbidden [O III]-emission line luminosities in FRII radiogalaxies

Cited by 75 publications

References 0 publications

An optical spectroscopic survey of the 3CR sample of radio galaxies withz$\mathsf{<}$ 0.3

An optical spectroscopic survey of the 3CR sample of radio galaxies withz$\mathsf{<}$ 0.3

Radio and spectroscopic properties of miniature radio galaxies: revealing the bulk of the radio-loud AGN population

Classifying radio emitters from the Sloan Digital Sky Survey

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