Optical spectroscopy of a complete sample of southern 2-Jy radio sources*

Tadhunter, C. N.; Morganti, Raffaella; Alighieri, S. di Serego; Fosbury, R. A. E.; Danziger, I. J.

doi:10.1093/mnras/263.4.999

Cited by 213 publications

(293 citation statements)

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“…This is very similar to the steep spectral indices α ∼ −1.0 that are characteristic of high-redshift radio galaxies, making it even more difficult to disentangle the contribution of AGNs and star formation to lower-power radio sources than those studied here. In spite of their faintness relative to other high-redshift radio galaxies, the radio power of fainter sources in this present study is nonetheless comparable to that of the most powerful radio galaxies known at low redshift (e.g., Tadhunter et al 1993). …”

Section: Samplementioning

confidence: 42%

Kinematic signatures of AGN feedback in moderately powerful radio galaxies atz~ 2 observed with SINFONI

Collet

Nesvadba

Breuck

et al. 2016

A&A

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Most successful galaxy formation scenarios now postulate that the intense star formation in massive, high-redshift galaxies during their major growth period was truncated when powerful AGNs launched galaxy-wide outflows of gas that removed large parts of the interstellar medium. SINFONI imaging spectroscopy of the most powerful radio galaxies at z ∼ 2 show clear signatures of such winds, but are too rare to be good representatives of a generic phase in the evolution of all massive galaxies at high redshift. Here we present SINFONI imaging spectroscopy of the rest-frame optical emission-line gas in 12 radio galaxies at redshifts ∼2. Our sample spans a range in radio power that is intermediate between the most powerful radio galaxies with known wind signatures at these redshifts and vigorous starburst galaxies, and are about two orders of magnitude more common than the most powerful radio galaxies. Thus, if AGN feedback is a generic phase of massive galaxy evolution for reasonable values of the AGN duty cycle, these are just the sources where AGN feedback should be most important. Our sources show a diverse set of gas kinematics ranging from regular velocity gradients with amplitudes of Δv = 200−400 km s −1 consistent with rotating disks to very irregular kinematics with multiple velocity jumps of a few 100 km s −1 . Line widths are generally high, typically around FWHM = 800 km s −1 , more similar to the more powerful high-z radio galaxies than mass-selected samples of massive high-z galaxies without bright AGNs, and consistent with the velocity range expected from recent hydrodynamic models. A broad Hα line in one target implies a black hole mass of a few 10 9 M . Velocity offsets of putative satellite galaxies near a few targets suggest dynamical masses of a few 10 11 M for our sources, akin to the most powerful high-z radio galaxies. Ionized gas masses are 1−2 orders of magnitude lower than in the most powerful radio galaxies, and the extinction in the gas is relatively low, up to A V ∼ 2 mag. The ratio of line widths, σ, to bulk velocity, v, is so large that even the gas in galaxies with regular velocity fields is unlikely to be gravitationally bound. It is unclear, however, whether the large line widths are due to turbulence or unresolved, local outflows as are sometimes observed at low redshifts. We compare our sources with sets of radio galaxies at low and high redshift, finding that they may have more in common with gas-rich nearby radio galaxies with similar jet power than with the most powerful high-z radio galaxies. Comparison of the kinetic energy with the energy supply from the AGNs through jet and radiation pressure suggests that the radio source still plays a dominant role for feedback, consistent with low-redshift radio-loud quasars.

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Section: Samplementioning

confidence: 42%

Kinematic signatures of AGN feedback in moderately powerful radio galaxies atz~ 2 observed with SINFONI

Collet

Nesvadba

Breuck

et al. 2016

A&A

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“…We estimate the uncertainty of the line fluxes from the subtraction of the underlying noisy continuum to < ∼ 40%; combined with the absolute flux calibration uncertainty of < ∼ 20% this results in a total line flux uncertainty of ∼50% which is sufficient for the conclusions drawn here. In order to compare the two samples by means of representative lines, when such a line is unobserved or poorly measured, we substitute it by another one of similar (or higher) ionisation potential with appropriately scaled strength determined from average line ratios: [ Grimes et al (2004) and from Boroson & Oke (1984), Tadhunter et al (1993), Mc Carthy et al (1995 and Hirst et al (2003 8 µm values are much higher (by a factor ∼100) than those found for starburst galaxies (Sturm et al 2002), placing also the FR 2 galaxies clearly in the AGN dominated range. We find also similar results using other lines, e.g.…”

Section: Resultsmentioning

confidence: 99%

Spitzer IRS spectroscopy of 3CR radio galaxies and quasars: testing the unified schemes

Haas

Siebenmorgen

Schulz

et al. 2005

A&A

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With the Spitzer Space Telescope Infrared Spectrograph (IRS) we have observed seven powerful FR 2 radio galaxies and seven quasars. Both samples, the galaxies and the quasars, are comparable in isotropic 178 MHz luminosity (10 26.5 W/Hz < ∼ P 178 MHz < ∼ 10 29.5 W/Hz) and in redshift range (0.05 < ∼ z < ∼ 1.5). We find for both samples similar distributions in the luminosity ratios of high-to low-excitation lines ([NeV] 14.3 µm / [NeII] 12.8 µm ) and of high-excitation line to radio power ([NeV] 24.3 µm / P 178 MHz ). This solves the long debate about the apparent difference of quasars and radio galaxies in favor of the orientation-dependent unified schemes. Furthermore, the luminosity ratio [OIII] 500.7 nm / [OIV] 25.9 µm of most galaxies is by a factor of ten lower than that of the quasars. This suggests that the optical emission from the central NLR is essentially absorbed (A V > ∼ 3) in the powerful FR 2 galaxies and that the [OIII] 500.7 nm luminosity does not serve as isotropic tracer for testing the unified schemes.

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“…The new sample, hereafter referred to as the z0.1 sample, consists of all radio-loud AGN with visible structure beyond the nucleus lying in the redshift range 0.01 z 0.2 from two flux-limited radio surveys: the 3CRR survey (Laing et al 1983) and the subsample of the 2Jy survey (Wall & Peacock 1985;Tadhunter et al 1993) defined by Dicken et al (2008). The initial sample contained 38 3CRR and 22 2Jy sources, but five sources were excluded.…”

Section: The Samplementioning

confidence: 99%

The link between accretion mode and environment in radio-loud active galaxies

Ineson

Croston

Hardcastle

et al. 2015

Mon. Not. R. Astron. Soc.

130

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The interactions between radio-loud AGN and their environments play an important rôle in galaxy and cluster evolution. Recent work has demonstrated fundamental differences between High and Low Excitation Radio Galaxies (HERGs and LERGs), and shown that they may have different relationships with their environments. In the Chandra Large Project ERA (Environments of Radio-loud AGN), we made the first systematic X-ray environmental study of the cluster environments of radio galaxies at a single epoch (z ∼ 0.5), and found tentative evidence for a correlation between radio luminosity and cluster X-ray luminosity. We also found that this relationship appeared to be driven by the LERG sub-population (Ineson et al. 2013).We have now repeated the analysis with a low redshift sample (z ∼ 0.1), and found strong correlations between radio luminosity and environment richness and between radio luminosity and central density for the LERGs but not for the HERGs. These results are consistent with models in which the HERGs are fuelled from accretion discs maintained from local reservoirs of gas, while LERGs are fuelled more directly by gas ingested from the intra-cluster medium.Comparing the samples, we found that although the maximum environment richness of the HERG environments is similar in both samples, there are poorer HERG environments in the z ∼ 0.1 sample than in the z ∼ 0.5 sample. We have therefore tentative evidence of evolution of the HERG environments. We found no differences between the LERG subsamples for the two epochs, as would be expected if radio and cluster luminosity are related.

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Optical spectroscopy of a complete sample of southern 2-Jy radio sources*

Cited by 213 publications

References 0 publications

Kinematic signatures of AGN feedback in moderately powerful radio galaxies atz~ 2 observed with SINFONI

Kinematic signatures of AGN feedback in moderately powerful radio galaxies atz~ 2 observed with SINFONI

Spitzer IRS spectroscopy of 3CR radio galaxies and quasars: testing the unified schemes

The link between accretion mode and environment in radio-loud active galaxies

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