High Redshift Radio Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900109957 ◽

1996 ◽

Vol 168 ◽

pp. 79-87

Author(s):

James S. Dunlop

Keyword(s):

High Redshift ◽

Spatial Association ◽

Radio Galaxies ◽

Elliptical Galaxies ◽

Powerful Radio ◽

High Redshift Galaxies ◽

3 Dimensional ◽

Baryonic Mass ◽

Radio Power

The potentially important role of jet-cloud interactions in determining the appearance of high-redshift radio galaxies is discussed and investigated via new 3-dimensional simulations of off-axis jet-cloud collisions. The results indicate that the most powerful radio sources are likely to be observed during or shortly after a jet-cloud interaction, and that such interactions can explain both the radio structures and the spatial association between optical and radio light found in powerful radio galaxies at high redshift. It is argued that, due to the radio-power dependence of such complicating effects, the optical-infrared colours and morphologies of very radio-luminous high-redshift galaxies can tell us essentially nothing about their evolutionary state. Either one must study much less radio-luminous sources in which the AGN-induced contamination is minimised, or one must attempt to determine what fraction of the baryonic mass of the radio galaxy has been converted into stars at the epoch of observation. Recent observations aimed at performing the latter experiment on two well-known high-redshift radio galaxies (4C 41.17 & B2 0902+34) are described. It is concluded that at present there exists no clear evidence that either of these famous galaxies is ‘primæval’; on the contrary, the continued low-dispersion of the infrared Hubble diagram atz> 2 points toward a much higher redshift of formation for elliptical galaxies.

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High-Redshift Milli-Jansky Radio Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900081912 ◽

1996 ◽

Vol 175 ◽

pp. 581-582

Author(s):

J. Dunlop ◽

J. Peacock ◽

R. Windhorst ◽

H. Spinrad ◽

A. Dey ◽

...

Keyword(s):

Luminosity Function ◽

High Redshift ◽

Radio Galaxies ◽

Elliptical Galaxies ◽

Observational Cosmology ◽

Redshift Distribution ◽

Flux Limit ◽

Formation And Evolution ◽

Radio Luminosity Function ◽

Radio Power

The study of radio galaxies selected at mJy flux levels has the potential to resolve two important issues in observational cosmology provided redshifts can be determined or reliably estimated for complete samples of such sources. First, the deep flux limit, combined with the shape of the radio luminosity function means that the redshift distribution of such samples provides a much more powerful test of the existence of a high-redshift cutoff for radio sources (Dunlop & Peacock 1990) than can be provided by further studies of brighter radio samples. Second, as a consequence of selection from bright radio surveys, the detailed study of galaxies at z > 2 has to date been confined to objects of extreme radio power (e.g. 4C41.17, Chambers et al. 1990; B2 0902+34, Eales et al. 1993), and it has now become clear that the ultraviolet-infrared properties of such sources are strongly contaminated by processes connected to the AGN (Eales & Rawlings 1993; Dunlop & Peacock 1993). Being 100-1000 times less radio luminous than these extreme sources, mJy radio galaxies at comparable redshifts should provide much more representative probes of the formation and evolution of elliptical galaxies in general.

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The SINFONI survey of powerful radio galaxies at z ~ 2: Jet-driven AGN feedback during the Quasar Era

Astronomy and Astrophysics ◽

10.1051/0004-6361/201528040 ◽

2017 ◽

Vol 599 ◽

pp. A123 ◽

Cited By ~ 27

Author(s):

N. P. H. Nesvadba ◽

C. De Breuck ◽

M. D. Lehnert ◽

P. N. Best ◽

C. Collet

Keyword(s):

Kinetic Energy ◽

Interstellar Medium ◽

Large Scale ◽

High Redshift ◽

Radio Galaxies ◽

Energy Output ◽

Host Galaxy ◽

Powerful Radio ◽

Massive Galaxies ◽

Gas Kinematics

We present VLT/SINFONI imaging spectroscopy of the rest-frame optical emission lines of warm ionized gas in 33 powerful radio galaxies at redshifts z ≳ 2, which are excellent sites to study the interplay of rapidly accreting active galactic nuclei and the interstellar medium of the host galaxy in the very late formation stages of massive galaxies. Our targets span two orders of magnitude in radio size (2−400 kpc) and kinetic jet energy (a few 1046– almost 1048 erg s-1). All sources have complex gas kinematics with broad line widths up to ~1300 km s-1. About half have bipolar velocity fields with offsets up to 1500 km s-1 and are consistent with global back-to-back outflows. The others have complex velocity distributions, often with multiple abrupt velocity jumps far from the nucleus of the galaxy, and are not associated with a major merger in any obvious way. We present several empirical constraints that show why gas kinematics and radio jets seem to be physically related in all galaxies of the sample. The kinetic energy in the gas from large scale bulk and local outflow or turbulent motion corresponds to a few 10-3 to 10-2 of the kinetic energy output of the radio jet. In galaxies with radio jet power ≳ 1047 erg s-1, the kinetic energy in global back-to-back outflows dominates the total energy budget of the gas, suggesting that bulk motion of outflowing gas encompasses the global interstellar medium. This might be facilitated by the strong gas turbulence, as suggested by recent analytical work. We compare our findings with recent hydrodynamic simulations, and discuss the potential consequences for the subsequent evolution of massive galaxies at high redshift. Compared with recent models of metal enrichment in high-z AGN hosts, we find that the gas-phase metallicities in our galaxies are lower than in most low-z AGN, but nonetheless solar or even super-solar, suggesting that the ISM we see in these galaxies is very similar to the gas from which massive low-redshift galaxies formed most of their stars. This further highlights that we are seeing these galaxies near the end of their active formation phase.

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Outflows from ellipticals: the role of supernovae

Symposium - International Astronomical Union ◽

10.1017/s0074180900213016 ◽

2003 ◽

Vol 212 ◽

pp. 630-636

Author(s):

Francesca Matteucci ◽

Antonio Pipino

Keyword(s):

Star Formation ◽

Dominant Role ◽

High Redshift ◽

Elliptical Galaxies ◽

Type Ii ◽

Chemical Enrichment ◽

Galactic Winds ◽

Type Ia ◽

Intense Burst

Models of supernova (SN) driven galactic winds for ellipticals are presented. We assume that ellipticals formed at high redshift and suffered an intense burst of star formation. The role of supernovae of Type II and Type Ia in the chemical enrichment and in triggering galactic winds is studied. In particular, several recipes for SN feed-back together with detailed nucleosynthesis prescriptions are considered. It is shown that SNe of Type II have a dominant role in enriching the interstellar medium of elliptical galaxies whereas Type Ia SNe dominate the enrichment and the energetics of the intracluster medium.

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Optical and IR Properties of Radio Galaxies as a Function of their Radio Power

Symposium - International Astronomical Union ◽

10.1017/s0074180900233330 ◽

1996 ◽

Vol 171 ◽

pp. 414-414

Author(s):

L. Maxfield ◽

S.G. Djorgovski ◽

D. Thompson ◽

M.A. Pahre ◽

R.R. de Carvalho ◽

...

Keyword(s):

High Redshift ◽

Spectroscopic Properties ◽

Radio Galaxies ◽

Active Nucleus ◽

Data Set ◽

Uv Emission ◽

Two Samples ◽

Order Of Magnitude ◽

Ir Photometry ◽

Radio Power

We compare optical and infrared photometric and spectroscopic properties of high-redshift radio galaxies from the 3CR and B3 surveys. At a given redshift and a fixed restframe frequency, the two samples differ on average by an order of magnitude in radio power, thus providing a fair baseline in radio powerfor a range of redshifts. We present new optical and IR photometry and spectrosopy for a number of B3 sources. We combine these data with the existing corresponding information on B3 and 3CR sources, in order to explore different correlations of source properties with redshift, and among themselves. B3 sources follow the same trend as 3CR's in the K band Hubble diagram, although they do seem to be slightly fainter on average at a given redshift. This trend is slightly more prominent in the Gunn r band. This suggests that some fraction of the observed light in the r and K bands is contributed by an active nucleus, which also powers the radio lobes. The B3's also tend to have lower emission line luminosities than 3CR's at any given redshift, suggesting that there may be a correlation between line luminosity and radio power. Such a correlation is clearly seen and is followed by both samples. It suggests that the UV emission lines are largely powered by the active nucleus, ostensibly a hidden quasar, which is also responsible for the radio emission. We also examine the behavior of the optical and radio PA alignments for the combined B3+3CR data set. We find that high-power and high-redshift subsamples for both B3's and 3CR's show the alignments more prominently, but we still cannot tell which of these variables dominates this effect. This work was supported in part by the NSF PYI award AST-9157412, and the Bressler Foundation.

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Radio Galaxies as Large-Scale Cosmological Probes

Symposium - International Astronomical Union ◽

10.1017/s0074180900137064 ◽

1988 ◽

Vol 130 ◽

pp. 579-579

Author(s):

J.A. Peacock ◽

L. Miller ◽

C.A. Collins ◽

D. Nicholson ◽

S. J. Lilly

Keyword(s):

Large Scale ◽

A Priori ◽

Radio Galaxies ◽

Elliptical Galaxies ◽

Central Component ◽

Selection Effects ◽

Core Radius ◽

Point Correlation ◽

Point Correlation Function ◽

Radio Power

We are working on an all-sky sample of radio-selected elliptical galaxies to provide a powerful probe of clustering & streaming velocities on 10–100 Mpc scales. Our eventual sample will have the limits (i) S>0.5 Jy at 1.4 GHz; (ii) 0.01<z<0.1; (iii) |b| >15°; about 400 galaxies satisfy these criteria. We are pursuing an optical programme to obtain (i) B & I CCD frames for all galaxies; (ii) spectra for the galaxies without accurate redshifts; this is now about 30% complete. Accurate optical luminosity indicators exist for radio galaxies, without needing to measure velocity dispersions (using the correlations with optical core radius and radio central-component luminosity: Hoessel 1980: Ap. J. 241, 493; Fabbiano et al. 1984: Ap. J. 277, 115). We therefore expect to provide an accurate test of the Rubin-Ford effect, and to extend such studies to higher redshift. We also have a preliminary result for the 3D two-point correlation function of radio galaxies (see Figure). This strong clustering signal is seen only from galaxies in the decade of radio power below the Fanaroff-Riley division. These objects are known a priori to lie in cluster environments of average Abell richness 0 (Longair & Seldner 1979: MNRAS 189, 433). This result therefore provides confirmation of a trend of clustering with richness independent of optical selection effects in choosing a cluster sample.

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THE RELATION BETWEEN COMPACT, QUIESCENT HIGH-REDSHIFT GALAXIES AND MASSIVE NEARBY ELLIPTICAL GALAXIES: EVIDENCE FOR HIERARCHICAL, INSIDE-OUT GROWTH

The Astrophysical Journal ◽

10.1088/0004-637x/697/2/1290 ◽

2009 ◽

Vol 697 (2) ◽

pp. 1290-1298 ◽

Cited By ~ 329

Author(s):

Rachel Bezanson ◽

Pieter G. van Dokkum ◽

Tomer Tal ◽

Danilo Marchesini ◽

Mariska Kriek ◽

...

Keyword(s):

High Redshift ◽

Elliptical Galaxies ◽

High Redshift Galaxies ◽

Inside Out ◽

Redshift Galaxies

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Radio Emission from High Redshift Galaxies: VLA Observations of the Hubble Deep Field

Symposium - International Astronomical Union ◽

10.1017/s007418090012902x ◽

1998 ◽

Vol 179 ◽

pp. 356-357

Author(s):

E.A. Richards

Keyword(s):

Radio Emission ◽

Small Area ◽

High Redshift ◽

Radio Galaxies ◽

Radio Sources ◽

High Redshift Galaxies ◽

Area 5 ◽

Moderate Power ◽

Galaxy Populations ◽

Hubble Deep Field

To study galaxy populations and their evolution at the highest possible redshifts, a small area of the sky, the Hubble Deep Field (HDF) was imaged to an unprecedented sensitivity of R = 29.5 (Williams et al. 1996). As a complement to the HST observations, we have used the VLA at 8 GHz to image an area 5.′4 in diameter (FWHM) centered on the HDF to an rms sensitivity of 2 μJy. With a radio resolution of about 3″, we have 33 sources above 9.5 μJy, seven in the 4 arcmin2 HDF field of which six have clear optical IDs. There are an additional 12 IDs in the HST flanking fields. The optical counterparts of the radio sources are a mixture of ellipticals, spirals, and irregulars, consistent with earlier surveys of comparable depth (Windhorst et al. 1995). With a median redshift <z> ∼ 1, the radio galaxies we are sampling are somewhat more distant than the classical starbursting galaxies which dominate less sensitive radio surveys. Our HDF identifications are predominately with post-starburst galaxies, moderate power AGN, and blue irregulars (Fomalont et al. 1996).

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Radio Source Environments at Redshifts > 0.5

Symposium - International Astronomical Union ◽

10.1017/s0074180900080943 ◽

1996 ◽

Vol 175 ◽

pp. 321-322

Author(s):

M. Lacy ◽

S. Rawlings ◽

M. Wold ◽

A. Bunker ◽

K.M. Blundell ◽

...

Keyword(s):

Radio Source ◽

High Redshift ◽

Elliptical Galaxies ◽

Radio Sources ◽

Powerful Radio ◽

Host Galaxies ◽

Local Universe ◽

Wide Range ◽

Age Of The Universe ◽

The Universe

The most powerful radio sources in the local Universe are found in giant elliptical galaxies. Looking back to a redshift of 0.5 (≈ half the age of the Universe for ω = 1), we see that these host galaxies are increasingly found in moderately rich clusters. This fact gives us hope that radio sources can be used as tracers of high density environments at high redshift. By exploiting radio source samples selected over a wide range in luminosity (Blundell et al., these proceedings), we will also be able to test whether the luminosities of radio sources are correlated with their environments.

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