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 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 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.

Cold gas studies of a z = 2.5 protocluster

2020 ◽  
Vol 15 (S359) ◽  
pp. 136-140
Author(s):  
Minju M. Lee ◽  
Ichi Tanaka ◽  
Rohei Kawabe
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Kinematic Model ◽  
Molecular Gas ◽  
General View ◽  
Massive Galaxies ◽  
Star Forming ◽  
Gas Kinematics ◽  
Narrow Band Filter ◽  
Stellar Masses

AbstractWe present studies of a protocluster at z =2.5, an overdense region found close to a radio galaxy, 4C 23.56, using ALMA. We observed 1.1 mm continuum, two CO lines (CO (4–3) and CO (3–2)) and the lower atomic carbon line transition ([CI](3P1-3P0)) at a few kpc (0″.3-0″.9) resolution. The primary targets are 25 star-forming galaxies selected as Hα emitters (HAEs) that are identified with a narrow band filter. These are massive galaxies with stellar masses of > 1010Mʘ that are mostly on the galaxy main sequence at z =2.5. We measure the molecular gas mass from the independent gas tracers of 1.1 mm, CO (3–2) and [CI], and investigate the gas kinematics of galaxies from CO (4–3). Molecular gas masses from the different measurements are consistent with each other for detection, with a gas fraction (fgas = Mgas/(Mgas+ Mstar)) of ≃ 0.5 on average but with a caveat. On the other hand, the CO line widths of the protocluster galaxies are typically broader by ˜50% compared to field galaxies, which can be attributed to more frequent, unresolved gas-rich mergers and/or smaller sizes than field galaxies, supported by our high-resolution images and a kinematic model fit of one of the galaxies. We discuss the expected scenario of galaxy evolution in protoclusters at high redshift but future large surveys are needed to get a more general view.

scholarly journals The radio properties of high-excitation radio galaxies with intermediate radio powers

2020 ◽  
Vol 494 (2) ◽  
pp. 2053-2067
Author(s):  
J C S Pierce ◽  
C N Tadhunter ◽  
R Morganti
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
High Sensitivity ◽  
Seyfert Galaxies ◽  
Radio Galaxies ◽  
Host Galaxy ◽  
High Excitation ◽  
Power Sources ◽  
Very Large Array ◽  
Extended Radio

ABSTRACT In the past decade, high-sensitivity radio surveys have revealed that the local radio active galactic nucleus population is dominated by moderate-to-low power sources with emission that is compact on galaxy scales. High-excitation radio galaxies (HERGs) with intermediate radio powers (22.5 &lt; log (L1.4 GHz) &lt; 25.0 W Hz−1) form an important sub-group of this population, since there is strong evidence that they also drive multiphase outflows on the scales of galaxy bulges. Here, we present high-resolution Very Large Array observations at 1.5, 4.5, and 7.5 GHz of a sample of 16 such HERGs in the local universe (z &lt; 0.1), conducted in order to investigate the morphology, extent, and spectra of their radio emission in detail, down to sub-kpc scales. We find that the majority (56 per cent) have unresolved structures at the limiting angular resolution of the observations (∼0.3 arcsec). Although similar in the compactness of their radio structures, these sources have steep radio spectra and host galaxy properties that distinguish them from local low-excitation radio galaxies that are unresolved on similar scales. The remaining sources exhibit extended radio structures with projected diameters ∼1.4–19.0 kpc and a variety of morphologies: three double-lobed; two large-scale diffuse; one jetted and ‘S-shaped’; one undetermined. Only 19 per cent of the sample therefore exhibit the double-lobed/edge-brightened structures often associated with their counterparts at high and low radio powers: radio-powerful HERGs and Seyfert galaxies, respectively. Additional high-resolution observations are required to investigate this further, and to probe the ≲300 pc scales on which some Seyfert galaxies show extended structures.

scholarly journals ASYMMETRIES OF AGN JETS IN INHOMOGENEOUS MEDIA

2014 ◽  
Vol 28 ◽  
pp. 1460192
Author(s):  
VOLKER GAIBLER
Keyword(s):  
Interstellar Medium ◽  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Inhomogeneous Media ◽  
Host Galaxy ◽  
Radio Sources ◽  
Propagation Models ◽  
Hydrodynamical Simulations

Considerable asymmetries in jets from active galactic nuclei (AGN) and associated double radio sources can be caused by an inhomogeneous interstellar medium of the host galaxy. These asymmetries can easily be estimated by 1D propagation models, but hydrodynamical simulations have shown that the actual asymmetries can be considerably larger. With a set of smaller-scale hydrodynamical simulations we examine these asymmetries, and find they are typically a factor of ~ 3 larger than in 1D models. We conclude that, at high redshift, large asymmetries in radio sources are expected in gas-rich galaxies with a clumpy interstellar medium.

scholarly journals Metallicity of the high-redshift Universe traced by radio galaxies

2009 ◽  
Vol 5 (S265) ◽  
pp. 179-180
Author(s):  
K. Matsuoka ◽  
T. Nagao ◽  
R. Maiolino ◽  
A. Marconi ◽  
Y. Taniguchi
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Radio Galaxies ◽  
Narrow Line ◽  
Line Flux ◽  
Model Calculations ◽  
Massive Galaxies ◽  
High Redshift Universe ◽  
Photoionization Model ◽  
Very High

AbstractWe investigate the metallicity of the narrow line regions (NLRs) of high-z radio galaxies (HzRGs), using new deep optical spectra of 9 HzRGs obtained with FORS2 on VLT and data from the literature. To estimate the metallicity of NLRs we focus on the Civ/Heii and Ciii]/Civ flux ratios. Based on comparison between the observed emission-line flux ratios and the prediction of our photoionization model calculations, we find no significant metallicity evolution in NLRs of HzRGs, up to z ~ 4. We discuss the possibility that massive galaxies had almost completed the major epoch of the star formation in the very high-z universe (z > 5).

scholarly journals Quasar Metal Abundances & Host Galaxy Evolution

2009 ◽  
Vol 5 (S265) ◽  
pp. 171-178
Author(s):  
Fred Hamann ◽  
Leah E. Simon
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
High Redshift ◽  
Big Bang ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Massive Galaxies ◽  
Central Regions ◽  
Metal Abundances ◽  
The Big Bang

AbstractHigh-redshift quasars provide a unique glimpse into the early evolution of massive galaxies. The physical processes that trigger major bursts of star formation in quasar host galaxies (mergers and interactions) probably also funnel gas into the central regions to grow the super-massive black holes (SMBHs) and ignite the luminous quasar phenomenon. The globally dense environments where this occurs were probably also among the first to collapse and manufacture stars in significant numbers after the big bang. Measurements of the elemental abundances near quasars place important constraints on the nature, timing and extent of this star formation. A variety of studies using independent emission and absorption line diagnostics have shown that quasar environments have gas-phase metallicities that are typically a few times solar at all observed redshifts. These results are consistent with galaxy evolution scenarios in which large amounts of star formation (e.g., in the central regions) precede the visibly bright quasar phase. An observed trend for higher metallicities in more luminmous quasars (powered by more massive SMBHs) is probably tied to the well-known mass–metallicity relation among ordinary galaxies. This correlation and the absence of a trend with redshift indicate that mass is a more important parameter in the evolution than the time elapsed since the big bang.

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 Gas kinematics in powerful radio galaxies atz~ 2: Energy supply from star formation, AGN, and radio jets

2017 ◽  
Vol 600 ◽  
pp. A121 ◽  
Author(s):  
N. P. H. Nesvadba ◽  
G. Drouart ◽  
C. De Breuck ◽  
P. Best ◽  
N. Seymour ◽  
...  
Keyword(s):  
Star Formation ◽  
Energy Supply ◽  
Radio Galaxies ◽  
Powerful Radio ◽  
Gas Kinematics ◽  
Radio Jets

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.

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