[O III] 500.7 spectroscopy of 3C galaxies and quasars at redshift z &gt; 1

Jackson, N.; Rawlings, Steve

doi:10.1093/mnras/286.1.241

Cited by 144 publications

(206 citation statements)

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“…High resolution radio images for all but one object, 3C 403.1, were available. All relevant optical spectroscopic classifications are extracted from Jackson & Rawlings (1997), Hardcastle et al (1998Hardcastle et al ( , 1999, and Morganti et al (1997). We note that BLRG 3C 120 differs from the rest of the selected BLRG subsample, since it is strongly core-dominated and has a FR-I morphology.…”

Section: Sample Selectionmentioning

confidence: 99%

“…LEGs have dominating low-excitation and/or weak/absent high-excitation emission. They are identified on the basis of one or more of the following criteria: emission-line ratios [ A64 (2010) or strengths log νL [O III] < 40.7 erg s −1 including for stellar absorption lines or the 4000 Å-break, while for HEGs these emission-line ratios, equivalent widths, and strengths are higher Jackson & Rawlings 1997;Morganti et al 1997). Broad-line radio galaxies (BLRGs) are identified by having at least one broad emission-line (v FWHM > 2000 km s −1 ) .…”

Section: Introductionmentioning

confidence: 99%

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Dust tori in radio galaxies

Wolk¹,

Barthel²,

Peletier³

et al. 2010

A&A

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Aims. We investigate the quasar -radio galaxy unification scenario and detect dust tori within radio galaxies of various types. Methods. Using VISIR on the VLT, we acquired sub-arcsecond (∼0.40 ) resolution N-band images, at a wavelength of 11.85 μm, of the nuclei of a sample of 27 radio galaxies of four types in the redshift range z = 0.006−0.156. The sample consists of 8 edge-darkened, low-power Fanaroff-Riley class I (FR-I) radio galaxies, 6 edge-brightened, class II (FR-II) radio galaxies displaying low-excitation optical emission, 7 FR-IIs displaying high-excitation optical emission, and 6 FR-II broad emission line radio galaxies. Out of the sample of 27 objects, 10 nuclei are detected and several have constraining non-detections at sensitivities of 7 mJy, the limiting flux a point source has when detected with a signal-to-noise ratio of 10 in one hour of source integration. Results. On the basis of the core spectral energy distributions of this sample we find clear indications that many FR-I and several low-excitation FR-II radio galaxies do not contain warm dust tori. At least 57 ± 19 percent of the high-excitation FR-IIs and almost all of the broad line radio galaxies exhibit excess infrared emission, which must be attributed to warm dust reradiating accretion activity. The FR-I and low-excitation FR-II galaxies are all of low efficiency, which is calculated as the ratio of bolometric to Eddington luminosity L bol /L Edd < 10 −3 . This suggests that thick tori are absent at low accretion rates and/or low efficiencies. The high-excitation FR-II galaxies are a mixed population with three types of nuclei: 1) low efficiency with dust torus; 2) low efficiency with weakly emitting dust torus; and 3) high efficiency with weak dust torus. We argue that the unification viewing angle range 0-45 degrees of quasars should be increased to ∼60 degrees, at least at lower luminosities.

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Section: Sample Selectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dust tori in radio galaxies

Wolk¹,

Barthel²,

Peletier³

et al. 2010

A&A

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“…However, observational evidence is mounting to suggest that this picture does not give a proper description for low-luminosity radioloud AGN (P 1.4 GHz < ∼ 10 25 W Hz −1 ). These objects produce weaker or no emission lines (Hine & Longair 1979;Jackson & Rawlings 1997), lack the dusty torus infrared emission (Ogle et al 2006), and do not produce the accretion related X-ray emission (Hardcastle et al 2006). It has been suggested that there are indeed two very different modes of AGN activity named the "Quasar mode" and the "Radio mode" (Best et al 2005;Hardcastle et al 2007).…”

Section: Introductionmentioning

confidence: 99%

The dependence of X-ray AGN activity on host galaxy properties and environment

Tasse

Röttgering

Best

2010

A&A

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There is mounting evidence that active galactic nuclei (AGN) selected through optical emission lines or radio luminosities comprise two distinct AGN populations, whose activity is triggered by different processes. In two previous papers, we studied the host galaxies and environment of radio-loud AGN. In this third paper we study the properties of a sample of Type-2 AGN that were selected on the basis of their [2-10] keV X-ray luminosity. We find that the X-ray luminosity function is in good agreement with previous studies and that the fraction of galaxies hosting an X-ray AGN is a strong function of the stellar mass of the host galaxy. The shape of this fraction-mass relation is similar to the fraction of galaxies that are emission-line AGN, while it differs significantly from the relation observed for radio-selected AGN. The AGN in our sample tend to be located in underdense environments where galaxy mergers and interactions are likely to occur. For all host galaxy masses, the Type-2 AGN display a strong infrared excess at short (∼3.5 μm) wavelengths, suggesting the presence of hot dust possibly associated with a hot dusty torus. These results add weight to the belief that the X-ray selection criteria identifies a population of AGN similar to the emission-line selected population but distinct from the radio population at high masses.

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“…In contrast, the deeper MAQS is limited to #1 sr. Secondly, the BQS SSQs are typically #10 times brighter in the radio than the faintest end of the radio LF, L 408 #10 24.5 W Hz 21 sr 21 , where the comoving space density is an order of magnitude higher (Dunlop & Peacock 1990). The lack of BQS SSQs with fainter radio luminosities is difficult to explain without either a radio-optical correlation, or a strongly luminosity-dependent quasar fraction (Lawrence 1991;Jackson & Rawlings 1997;Serjeant et al, in preparation). For the quasar fraction to explain the deficit of low-L 408 BQS SSQs, the SSQ luminosity function would have to be non-monotonic (i.e., number density must not be a strictly decreasing function of luminosity).…”

Section: Bqs Outliersmentioning

confidence: 99%

The radio--optical correlation in steep-spectrum quasars

Serjeant

Rawlings

Maddox

et al. 1998

Monthly Notices of the Royal Astronomical Society

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A B S T R A C TUsing complete samples of steep-spectrum quasars, we present evidence for a correlation between radio and optical luminosity which is not caused by selection effects, nor caused by an orientation dependence (such as relativistic beaming), nor a by-product of cosmic evolution. We argue that this rules out models of jet formation in which there are no parameters in common with the production of the optical continuum. This is arguably the most direct evidence to date for a close link between accretion on to a black hole and the fuelling of relativistic jets. The correlation also provides a natural explanation for the presence of aligned optical/ radio structures in only the most radio-luminous high-redshift galaxies.

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[O III] 500.7 spectroscopy of 3C galaxies and quasars at redshift z > 1

Cited by 144 publications

References 0 publications

Dust tori in radio galaxies

Dust tori in radio galaxies

The dependence of X-ray AGN activity on host galaxy properties and environment

The radio--optical correlation in steep-spectrum quasars

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