scholarly journals KECK Spectropolarimetry of High Redshift Radio Galaxies

1996 ◽  
Vol 175 ◽  
pp. 402-404
Author(s):  
A. Cimatti ◽  
A. Dey ◽  
W. Van BREUGEL ◽  
R. Antonucci ◽  
H. Spinrad
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Radio Galaxies ◽  
Unified Model ◽  
Powerful Radio ◽  
Imaging Spectrometer ◽  
Alignment Effect ◽  
Stellar Radiation ◽  
Resolution Imaging ◽  
To Come

High redshift radio galaxies (HzRGs) are observable up to cosmological distances competitive with the most distant quasars. However, before using them as probes of galaxy evolution, it is crucial to separate the stellar and non-stellar components. One of the most striking properties of HzRGs is the alignment of the UV continuum with the axis of the radio source (alignment effect; McCarthy et al. 1987). However, the relative importance of the stellar and non-stellar radiation to the alignment effect is still unknown, although a significant fraction is recognized to come from scattering of anisotropic radiation emitted by the obscured nucleus, as expected in the unified model of powerful radio sources (di Serego Alighieri, Cimatti & Fosbury 1994). Spectropolarimetry is the most powerful technique to observe at the same time different radiation components, but the 4m class telescopes can reach a sufficient S/N ratio only on the few brightest objects. Therefore, in order to investigate the origin of the alignment effect and to test the validity of the unified model of powerful radio-loud AGN, we have started a program of optical spectropolarimetry of HzRGs with the W.M. Keck 10m telescope equipped with the Low Resolution Imaging Spectrometer (LRIS) in polarimetric mode.

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

2017 ◽  
Vol 599 ◽  
pp. A123 ◽  
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.

scholarly journals The XXL Survey

2019 ◽  
Vol 625 ◽  
pp. A111 ◽  
Author(s):  
Andrew Butler ◽  
Minh Huynh ◽  
Anna Kapińska ◽  
Ivan Delvecchio ◽  
Vernesa Smolčić ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Radio Galaxies ◽  
Optical Data ◽  
Scaling Relation ◽  
Radio Luminosity ◽  
Hot Gas ◽  
Luminosity Functions ◽  
Wide Range ◽  
Luminosity Evolution

The evolution of the comoving kinetic luminosity densities (Ωkin) of the radio loud high-excitation radio galaxies (RL HERGs) and the low-excitation radio galaxies (LERGs) in the ultimate XMM extragalactic survey south (XXL-S) field is presented. The wide area and deep radio and optical data of XXL-S have allowed the construction of the radio luminosity functions (RLFs) of the RL HERGs and LERGs across a wide range in radio luminosity out to high redshift (z = 1.3). The LERG RLFs display weak evolution: Φ(z)∝(1 + z)0.67 ± 0.17 in the pure density evolution (PDE) case and Φ(z)∝(1 + z)0.84 ± 0.31 in the pure luminosity evolution (PLE) case. The RL HERG RLFs demonstrate stronger evolution than the LERGs: Φ(z)∝(1 + z)1.81 ± 0.15 for PDE and Φ(z)∝(1 + z)3.19 ± 0.29 for PLE. Using a scaling relation to convert the 1.4 GHz radio luminosities into kinetic luminosities, the evolution of Ωkin was calculated for the RL HERGs and LERGs and compared to the predictions from various simulations. The prediction for the evolution of radio mode feedback in the Semi-Analytic Galaxy Evolution (SAGE) model is consistent with the Ωkin evolution for all XXL-S RL AGN (all RL HERGs and LERGs), indicating that the kinetic luminosities of RL AGN may be able to balance the radiative cooling of the hot phase of the IGM. Simulations that predict the Ωkin evolution of LERG equivalent populations show similar slopes to the XXL-S LERG evolution, suggesting that observations of LERGs are well described by models of SMBHs that slowly accrete hot gas. On the other hand, models of RL HERG equivalent populations differ in their predictions. While LERGs dominate the kinetic luminosity output of RL AGN at all redshifts, the evolution of the RL HERGs in XXL-S is weaker compared to what other studies have found. This implies that radio mode feedback from RL HERGs is more prominent at lower redshifts than was previously thought.

scholarly journals The Radio and Infrared Luminosities of 3CR Radio Galaxies - Are They Correlated?

1987 ◽  
Vol 124 ◽  
pp. 143-146
Author(s):  
M.G. Yates ◽  
L. Miller ◽  
J.A. Peacock
Keyword(s):  
High Redshift ◽  
Stellar Populations ◽  
Radio Galaxies ◽  
Photometric Study ◽  
Powerful Radio ◽  
Hubble Diagram ◽  
Limited Sample

The infrared photometric study of a sample of 90 3CR radio galaxies by Lilly & Longair (1984, hereafter LL) has demonstrated that the high redshift objects are brighter in the infrared than their low redshift counterparts; this has been interpreted as being entirely due to the evolution of their constituent stellar populations. There is however a great difference between the radio luminosities of the high and low redshift objects in this flux limited sample and we have therefore examined statistically the possibility of a correlation between the infrared and radio luminosities of these galaxies, the presence of which could bias our interpretation of the infrared Hubble diagram. We find that the radio and infrared luminosities do indeed correlate for the most powerful radio galaxies.

scholarly journals The Emission Line Properties of the 3CR Radio Galaxies at Redshift One: Shocks, Evolution, and the Alignment Effect

1999 ◽  
Vol 194 ◽  
pp. 241-245
Author(s):  
Philip Best ◽  
Huub Röttgering ◽  
Malcolm Longair
Keyword(s):  
Emission Line ◽  
Radio Source ◽  
Velocity Structure ◽  
Radio Galaxies ◽  
Linear Size ◽  
Continuum Emission ◽  
Radio Sources ◽  
Powerful Radio ◽  
Alignment Effect ◽  
Optical Continuum

The results of a deep spectroscopic campaign on powerful radio galaxies with redshifts z ˜ 1, to investigate in detail their emission line gas properties, are presented. Both the 2-dimensional velocity structure of the [OII] 3727 emission line and the ionisation state of the gas are found to be strongly dependent upon the linear size (age) of the radio source in a manner indicative of the emission line properties of small (young) radio sources being dominated by the passage of the radio source shocks. The consequences of this evolution throughout the few x107 year lifetime of the radio source are discussed, particularly with relation to the alignment of the UV–optical continuum emission of these objects along their radio axis, the nature of which shows similar evolution.

scholarly journals High Redshift Radio Galaxies

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.

A Search for CO Emission in High-Redshift Powerful Radio Galaxies

1996 ◽  
Vol 457 ◽  
pp. 658 ◽  
Author(s):  
A. S. Evans ◽  
D. B. Sanders ◽  
J. M. Mazzarella ◽  
P. M. Solomon ◽  
D. Downes ◽  
...  
Keyword(s):  
High Redshift ◽  
Radio Galaxies ◽  
Powerful Radio ◽  
Co Emission

scholarly journals The GLEAMing of the first supermassive black holes

2020 ◽  
Vol 37 ◽  
Author(s):  
Guillaume Drouart ◽  
Nick Seymour ◽  
Tim J. Galvin ◽  
Jose Afonso ◽  
Joseph R. Callingham ◽  
...  
Keyword(s):  
Near Infrared ◽  
High Redshift ◽  
Pilot Project ◽  
Radio Galaxies ◽  
Host Galaxy ◽  
Wide Field ◽  
Powerful Radio ◽  
Massive Galaxies ◽  
Luminous Objects

Abstract We present the results of a new selection technique to identify powerful ( $L_{\rm 500\,MHz} \gt 10^{27}\,\text{WHz}^{-1}$ ) radio galaxies towards the end of the Epoch of Reionisation. Our method is based on the selection of bright radio sources showing radio spectral curvature at the lowest frequency ( ${\sim}100\,\text{MHz}$ ) combined with the traditional faintness in K-band for high-redshift galaxies. This technique is only possible, thanks to the Galactic and Extra-galactic All-sky Murchison Wide-field Array survey which provides us with 20 flux measurements across the 70– $230\,\text{MHz}$ range. For this pilot project, we focus on the GAMA 09 field to demonstrate our technique. We present the results of our follow-up campaign with the Very Large Telescope, Australian Telescope Compact Array, and the Atacama Large Millimetre Array to locate the host galaxy and to determine its redshift. Of our four candidate high-redshift sources, we find two powerful radio galaxies in the $1<z<3$ range, confirm one at $z=5.55$ , and present a very tentative $z=10.15$ candidate. Their near-infrared and radio properties show that we are preferentially selecting some of the most radio luminous objects, hosted by massive galaxies very similar to powerful radio galaxies at $1<z<5$ . Our new selection and follow-up technique for finding powerful radio galaxies at $z>5.5$ has a high 25–50% success rate.

scholarly journals HST and KECK Observations of High Redshift Radio Galaxies

1996 ◽  
Vol 175 ◽  
pp. 577-580
Author(s):  
W.J.M. Van Breugel
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Hubble Space Telescope ◽  
High Redshift ◽  
Radio Galaxies ◽  
Space Telescope ◽  
Comprehensive Program ◽  
Resolution Imaging ◽  
High Spatial Resolution Imaging ◽  
Optical Telescopes

Together with several of my colleagues I have embarked on a comprehensive program to study the radio–aligned restframe UV structures in high redshift radio galaxies (HzRGs) using some of the world's premier optical telescopes: the Hubble Space Telescope for high spatial resolution imaging, and the Keck 10m telescope for high S/N spectropolarimetry. I will discuss some of our latest results from these observations which elucidate, and at the same time obscure, our evolving understanding of HzRGs.

Revealing AGN, young and old stellar populations in HzRGs with PEGASE.3

2013 ◽  
Vol 9 (S304) ◽  
pp. 307-310
Author(s):  
Guillaume Drouart ◽  
Carlos De Breuck ◽  
Joël Vernet ◽  
Brigitte Rocca Volmerange ◽  
Nicholas Seymour
Keyword(s):  
Galaxy Evolution ◽  
Stellar Population ◽  
Radio Galaxy ◽  
High Redshift ◽  
Radio Galaxies ◽  
Host Galaxies ◽  
Continuous Coverage ◽  
Near Ir ◽  
The Relationship ◽  
Very High

AbstractThe HeRGÉ (Herschel Radio Galaxy Evolution) project consists of a sample of 70 radio galaxies in the range 1 < z < 5.2. They benefit from continuous coverage from 3 to 870μm with Spitzer, Herschel and sub-mm ground-based instruments (SCUBA, LABOCA). As a calorimeter, IR is an excellent proxy to estimate the contribution of both AGN and starburst, making of radio galaxies perfect candidates to provide new insights into the relationship between AGN and their host galaxies. The IR SED fitting with empirical templates reveals that radio galaxies are luminous and that their black holes and their host galaxies are not growing simultaneously. Extending the SED to optical/near-IR on a subsample of 12 radio galaxies spanning 1 < z < 4 reveal the necessity of three components to reproduce the observations. Making use of the evolutionary code PEGASE.3 and an AGN torus model, we are able to estimate parameters from the AGN torus, the evolved stellar population and the starburst (SB). They reveal that radio galaxies are massive, evolved, forming the bulk of their mass at very high redshift in a short timescale, but experience episodic, strong SB events, often associated with an AGN activity.

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