A new determination of the luminosity function of radio galaxies and an investigation of the evolutionary properties of the radio galaxy population in the recent past

1979 ◽  
Vol 229 ◽  
pp. 25 ◽  
Author(s):  
D. L. Meier ◽  
M.-H. Ulrich ◽  
R. Fanti ◽  
I. Gioia ◽  
C. Lari
Keyword(s):  
Luminosity Function ◽  
Radio Galaxy ◽  
Radio Galaxies ◽  
Recent Past ◽  
Galaxy Population

scholarly journals The Evolution of the Radio Galaxy Population as Determined from Deep Radio-Optical Surveys

1983 ◽  
Vol 104 ◽  
pp. 73-79
Author(s):  
Harry van der Laan ◽  
Peter Katgert ◽  
Rogier Windhorst ◽  
Marc Oort
Keyword(s):  
Luminosity Function ◽  
Birth Rate ◽  
Radio Galaxy ◽  
Rate Function ◽  
Light Curves ◽  
Log P ◽  
Galaxy Population ◽  
Optical Surveys ◽  
Radio Luminosity Function

A first step in the study of the evolution of the radio galaxy population is the determination of the radio luminosity function (RLF), i.e. ρ(log P, z), which results from (and must finally be interpreted in terms of) ‘light curves’ of individual objects (i.e. P(t)) and the ‘birth rate’ function ṅ (log P, t).

scholarly journals Radio Source Evolution Derived from Low Frequency Surveys

2002 ◽  
Vol 199 ◽  
pp. 50-53
Author(s):  
C.A. Jackson ◽  
J.V. Wall
Keyword(s):  
Radio Source ◽  
Luminosity Function ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Parametric Models ◽  
Radio Luminosity ◽  
Space Density ◽  
Radio Data ◽  
Radio Luminosity Function

We find simple parametric models to describe the space density evolution of radio-loud AGN, treating FRI and FRII radio galaxies separately as the two parent populations in our dual-population unified scheme. In this we use low frequency radio data (v < 500 MHz), where radio samples are unbiased by Doppler beaming. Incorporated into this latest analysis is a new determination of the local radio luminosity function at 1.4 GHz from galaxies common to both the 2dFGRS and NVSS surveys.

scholarly journals The eMERLIN and EVN View of FR 0 Radio Galaxies

Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 106
Author(s):  
Ranieri D. Baldi ◽  
Gabriele Giovannini ◽  
Alessandro Capetti
Keyword(s):  
Radio Galaxy ◽  
Lorentz Factor ◽  
Radio Galaxies ◽  
Relativistic Jets ◽  
Radio Structure ◽  
Extended Radio ◽  
Twin Jets ◽  
Core Components ◽  
Galaxy Population ◽  
5 Ghz

We present the results from high-resolution observations carried out with the eMERLIN UK-array and the European VLBI network (EVN) for a sample of 15 FR 0s, i.e., compact core-dominated radio sources associated with nearby early-type galaxies (ETGs), which represent the bulk of the local radio galaxy population. The 5 GHz eMERLIN observations available for five objects exhibit sub-mJy core components and reveal pc-scale twin jets for four out of five FR 0s once the eMERLIN and JVLA archival visibilities data are combined. The 1.66 GHz EVN observations available for 10 FR 0s display one- and two-sided jetted morphologies and compact cores. The pc-scale core emission contributes, on average, to about one tenth of the total extended radio emission, although we noted an increasing core contribution for flat-/inverted-spectrum sources. We found an unprecedented linear correlation between the pc-scale core luminosity (∼1021.3–1023.6 W Hz−1) and [O III] line luminosity, generally considered as proxy of the accretion power, for a large sample of LINER-type radio-loud low-luminosity active nuclei, all hosted in massive ETGs, which include FR 0s and FR Is. This result represents further evidence of a common jet–disc coupling in FR 0s and FR Is, despite then differing in kpc-scale radio structure. For our objects and for other FR 0 samples reported in the literature, we estimated the jet brightness sidedness ratios, which typically range between one and three. This parameter roughly gauges the jet bulk Lorentz factor Γ, which turns out to range from 1 to 2.5 for most of the sample. This corroborates the scenario that FR 0s are characterized by mildly relativistic jets, possibly as a result of lower-spinning black holes (BHs) than the highly spinning BHs of relativistic-jetted radio galaxies, FR Is.

scholarly journals CHORUS. II. Subaru/HSC Determination of the Lyα Luminosity Function at z = 7.0: Constraints on Cosmic Reionization Model Parameter

2018 ◽  
Vol 867 (1) ◽  
pp. 46 ◽  
Author(s):  
Ryohei Itoh ◽  
Masami Ouchi ◽  
Haibin Zhang ◽  
Akio K. Inoue ◽  
Ken Mawatari ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Model Parameter

scholarly journals The Surface Density of Quasars

1978 ◽  
Vol 79 ◽  
pp. 295-303 ◽  
Author(s):  
J.G. Bolton ◽  
Ann Savage
Keyword(s):  
Surface Density ◽  
Luminosity Function ◽  
Statistical Significance ◽  
Comprehensive Investigation ◽  
Space Density ◽  
Close Pairs

A knowledge of the surface density of quasars as a function of magnitude is important for two reasons. Firstly it is necessary in order to assess the possible statistical significance of close pairs of quasars or the association between quasars and bright galaxies. Secondly it is a necessary step in the determination of the space density or luminosity function of QSOs. We have carried out what we believe to be currently the most comprehensive investigation into the surface density of quasars. Three techniques have been used in this investigation. These are

scholarly journals Radio Spectra and Particle Ages of the Head-Tail Radio Galaxy NGC1265

1996 ◽  
Vol 175 ◽  
pp. 347-348
Author(s):  
L. Feretti ◽  
G. Giovannini ◽  
U. Klein ◽  
K.-H. Mack ◽  
L.G. Sijbring
Keyword(s):  
Magnetic Field ◽  
Radio Galaxy ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Field Structure ◽  
Magnetic Field Structure ◽  
Linearly Polarized ◽  
Faraday Effects ◽  
Perseus Cluster ◽  
Comprehensive Study

We have performed sensitive observations of three classical head-tail radio galaxies at λ11.1, 6.3, and 2.8 cm using the Effelsberg 100-m telescope (Zech, 1994). Complete maps of the sources 3C129, NGC1265, and 3C465 were obtained, including the distributions of the linearly polarized intensity. Together with the low-frequency interferometric maps these allow a comprehensive study of their radio spectra and, based on models of particle losses, the derivations of particle ages across these sources. The highest frequency involved allows an unambiguous derivation of the projected magnetic field structure, unimpeded by Faraday effects. Here we focus on NGC1265, which is located in the Perseus Cluster.

scholarly journals NGC 3894: a young radio galaxy seen by Fermi-LAT

2020 ◽  
Vol 635 ◽  
pp. A185 ◽  
Author(s):  
G. Principe ◽  
G. Migliori ◽  
T. J. Johnson ◽  
F. D’Ammando ◽  
M. Giroletti ◽  
...  
Keyword(s):  
Radio Galaxy ◽  
Radio Galaxies ◽  
High Energy ◽  
Apparent Velocity ◽  
Large Area ◽  
Long Baseline ◽  
Full Period ◽  
Very Long Baseline Array ◽  
High Energy Emission ◽  
First Time

Context. According to radiative models, radio galaxies may produce γ-ray emission from the first stages of their evolution. However, very few such galaxies have been detected by the Fermi Large Area Telescope (LAT) so far. Aims. NGC 3894 is a nearby (z = 0.0108) object that belongs to the class of compact symmetric objects (CSOs, i.e., the most compact and youngest radio galaxies), which is associated with a γ-ray counterpart in the Fourth Fermi-LAT source catalog. Here we present a study of the source in the γ-ray and radio bands aimed at investigating its high-energy emission and assess its young nature. Methods. We analyzed 10.8 years of Fermi-LAT data between 100 MeV and 300 GeV and determined the spectral and variability characteristics of the source. Multi-epoch very long baseline array (VLBA) observations between 5 and 15 GHz over a period of 35years were used to study the radio morphology of NGC 3894 and its evolution. Results. NGC 3894 is detected in γ-rays with a significance >9σ over the full period, and no significant variability has been observed in the γ-ray flux on a yearly time-scale. The spectrum is modeled with a flat power law (Γ = 2.0 ± 0.1) and a flux on the order of 2.2 × 10−9 ph cm−2 s−1. For the first time, the VLBA data allow us to constrain with high precision the apparent velocity of the jet and counter-jet side to be βapp, NW = 0.132 ± 0.004 and βapp, SE = 0.065 ± 0.003, respectively. Conclusions. Fermi-LAT and VLBA results favor the youth scenario for the inner structure of this object, with an estimated dynamical age of 59 ± 5 years. The estimated range of viewing angle (10° < θ <  21°) does not exclude a possible jet-like origin of the γ-ray emission.

scholarly journals The morphological classification of distant radio galaxies explored with three-dimensional simulations

2019 ◽  
Vol 490 (1) ◽  
pp. 1363-1382 ◽  
Author(s):  
Michael D Smith ◽  
Justin Donohoe
Keyword(s):  
Radio Galaxy ◽  
Three Dimensional ◽  
Radio Galaxies ◽  
Morphological Classification ◽  
Helical Structures ◽  
Radio Jets ◽  
Source Type ◽  
Radio Lobe ◽  
Three Dimensional Simulations

ABSTRACT We explore the observational implications of a large systematic study of high-resolution three-dimensional simulations of radio galaxies driven by supersonic jets. For this fiducial study, we employ non-relativistic hydrodynamic adiabatic flows from nozzles into a constant pressure-matched environment. Synchrotron emissivity is approximated via the thermal pressure of injected material. We find that the morphological classification of a simulated radio galaxy depends significantly on several factors with increasing distance (i.e. decreasing observed resolution) and decreasing orientation often causing reclassification from FR II (limb-brightened) to FR I (limb-darkened) type. We introduce the Lobe or Limb Brightening Index (LBI) to measure the radio lobe type more precisely. The jet density also has an influence as expected with lower density leading to broader and bridged lobe morphologies as well as brighter radio jets. Hence, relating observed source type to the intrinsic jet dynamics is not straightforward. Precession of the jet direction may also be responsible for wide relaxed sources with lower LBI and FR class as well as for X-shaped and double–double structures. Helical structures are not generated because the precession is usually too slow. We conclude that distant radio galaxies could appear systematically more limb darkened due to merger-related redirection and precession as well as due to the resolution limitation.

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