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 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 Testing the Merger Hypothesis of Powerful Radio Galaxies

1999 ◽  
Vol 186 ◽  
pp. 353-353
Author(s):  
Aaron S. Evans ◽  
D.B. Sanders ◽  
Joseph M. Mazzarella
Keyword(s):  
Radio Galaxies ◽  
Molecular Gas ◽  
Powerful Radio ◽  
Limited Sample ◽  
Star Forming ◽  
Degree Of Irregularity ◽  
K Band

We present K′-band imaging and millimeter (CO) spectroscopy of a 60 and 100 μm flux-limited sample of 35 low redshift, powerful radio galaxies (LzPRGs: P178MHz > 1023.5 W Hz−1 and 0.01 < z < 0.22). These observations are being obtained to test the hypothesis that the radio activity in LzPRGs is triggered by the merger of gas-rich galaxies, as well as to look for evolutionary correlations between the degree of irregularity in the K′-band morphologies, the amount of star-forming molecular gas, and the radio morphologies.

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 &amp; 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&gt; 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 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 properties of the young stellar populations in powerful radio galaxies at low and intermediate redshifts

2007 ◽  
Vol 381 (2) ◽  
pp. 611-639 ◽  
Author(s):  
J. Holt ◽  
C. N. Tadhunter ◽  
R. M. González Delgado ◽  
K. J. Inskip ◽  
J. Rodriguez ◽  
...  
Keyword(s):  
Stellar Populations ◽  
Radio Galaxies ◽  
Powerful Radio ◽  
Intermediate Redshifts

scholarly journals The Stellar Mass Distribution of Powerful Radio Galaxies Across 1 < z < 5.2

2006 ◽  
Vol 2 (S235) ◽  
pp. 427-427
Author(s):  
Nick Seymour ◽  
D. Stern ◽  
C. De Breuck ◽  
Keyword(s):  
Rest Frame ◽  
High Redshift ◽  
Color Space ◽  
Radio Galaxies ◽  
Stellar Mass ◽  
Energy Output ◽  
Host Galaxy ◽  
Spectral Energy ◽  
Radio Luminosity ◽  
Powerful Radio

AbstractWe present the results of a comprehensive Spitzer survey of 70 radio galaxies across 1 < z < 5.2. Using IRAC (3.6–8.0μm), IRS (16 μm) and MIPS (24–160 μm) imaging, we decompose the rest-frame optical to infrared spectral energy distributions into stellar, AGN, and dust components and determine the contribution of host galaxy stellar emission at rest-frame 1.6 μm (H-band). We find that the fraction of emitted light at rest-frame 1.6 μm from stars is >80% for over half the high redshift radio galaxies. The other radio galaxies have 1.6 μm stellar fractions spanning the range 20–80%. The resultant stellar luminosities imply stellar masses of 1011−12M⊙, independent of redshift, indicating that radio galaxies are amoungst the most massive galaxies observed over this redshift range. Powerful radio galaxies tend to lie in a similar region of mid-IR color-color space as unobscured AGN, despite the inferred stellar contribution to their shorter-wavelength, mid-IR SEDs. The stellar fraction of the rest-frame 1.6 μm luminosity has no correlation with redshift, radio luminosity, or rest-frame mid-IR (5 μm) luminosity. The bolometric energy output of these sources is dominated by the infrared, and the mid-IR luminosities are found to be similar to that of lower redshift (z < 1) radio galaxies. As expected, these exceptionally high mid-IR luminosities are consistent with an obscured, highly-accreting AGN. A weak, but significant, correlation of stellar mass with radio luminosity is found, consistent with earlier results.

scholarly journals A Powerful Jet/Cloud Interaction in the Radio Galaxy PKS 2250-41

1996 ◽  
Vol 175 ◽  
pp. 227-229
Author(s):  
R. Morganti ◽  
C.N. Tadhunter ◽  
N. Clark ◽  
N. Killeen
Keyword(s):  
Emission Line ◽  
Strong Evidence ◽  
Radio Galaxy ◽  
High Redshift ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Excitation Mechanism ◽  
Powerful Radio ◽  
Radio Jets ◽  
Extended Emission

Extended emission line regions aligned with the radio axis are a common feature of powerful radio galaxies and there is much interest in the origin of the extended gas and excitation mechanism. One model that can produce this alignment is photoionization by anisotropic nuclear continuum radiation. However, strong evidence exists, especially in high redshift radio galaxies, for powerful interactions between the relativistic radio jets and the ISM/IGM. Here we present the results of our study of the southern radio galaxy PKS 2250–41 (z = 0.308). This object is the most spectacular found in a sample of southern radio sources studied by Tadhunter et al. (1993) and it displays particularly clear evidence for such an interaction (Tadhunter et al. 1994; Dickson et al. 1995).

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