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661. Radio-AGN feedback for 0.5<z<1
ID:
ivo://CDS.VizieR/J/MNRAS/445/955
Title:
Radio-AGN feedback for 0.5<z<1
Short Name:
J/MNRAS/445/955
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents the first measurement of the radio luminosity function of 'jet-mode' (radiatively inefficient) radio-AGN out to z=1, in order to investigate the cosmic evolution of radio-AGN feedback. Eight radio source samples are combined to produce a catalogue of 211 radio-loud AGN with 0.5<z<1.0, which are spectroscopically classified into jet-mode and radiative-mode (radiatively efficient) AGN classes. Comparing with large samples of local radio-AGN from the Sloan Digital Sky Survey, the cosmic evolution of the radio luminosity function of each radio-AGN class is independently derived. Radiative-mode radio-AGN show an order of magnitude increase in space density out to z~1 at all luminosities, consistent with these AGN being fuelled by cold gas. In contrast, the space density of jet-mode radio-AGN decreases with increasing redshift at low radio luminosities (L_1.4GHz_<~10^24^W/Hz) but increases at higher radio luminosities. Simple models are developed to explain the observed evolution. In the best-fitting models, the characteristic space density of jet-mode AGN declines with redshift in accordance with the declining space density of massive quiescent galaxies, which fuel them via cooling of gas in their hot haloes. A time delay of 1.5-2Gyr may be present between the quenching of star formation and the onset of jet-mode radio-AGN activity. The behaviour at higher radio luminosities can be explained either by an increasing characteristic luminosity of jet-mode radio-AGN activity with redshift (roughly as (1+z)^3^) or if the jet-mode radio-AGN population also includes some contribution of cold-gas-fuelled sources seen at a time when their accretion rate was low. Higher redshifts measurements would distinguish between these possibilities.
662. Radio and K-band obs. of Ultra-Steep sources
ID:
ivo://CDS.VizieR/J/MNRAS/347/837
Title:
Radio and K-band obs. of Ultra-Steep sources
Short Name:
J/MNRAS/347/837
Date:
21 Oct 2021
Publisher:
CDS
Description:
A sample of 76 ultra-steep spectrum (USS) radio sources is defined from the 843-MHz Sydney University Molonglo Sky Survey (SUMSS) and 1.4-GHz NRAO VLA Sky Survey (NVSS) radio surveys with spectral index {alpha}<-1.3 and S(1.4GHz)>15mJy; 71 of these sources without bright optical or near-infrared counterparts at 1.385GHz were observed with the Australia Telescope Compact Array (ATCA), providing 5arcsec resolution images and subarcsec positional accuracy. To identify their host galaxies, near-infrared K-band images were obtained with IRIS2 at the AAT and SofI at the NTT; 92% of the USS sources could be identified down to K~20.5. 142 FITS files containing the radio maps and the K-band images are included in the fits subdirectory.
663. Radio and X-ray-emitting broad-line AGNs
ID:
ivo://CDS.VizieR/J/ApJ/645/890
Title:
Radio and X-ray-emitting broad-line AGNs
Short Name:
J/ApJ/645/890
Date:
21 Oct 2021
Publisher:
CDS
Description:
We derived the black hole fundamental plane relationship between the 1.4GHz radio luminosity (Lr), 0.1-2.4keV X-ray luminosity (LX), and black hole mass (M) from a uniform broad-line SDSS AGN sample including both radio-loud and radio-quiet X-ray-emitting sources. We found in our sample that the fundamental plane relation has a very weak dependence on the black hole mass, and a tight correlation also exists between the Eddington-luminosity-scaled X-ray and radio luminosities for the radio-quiet subsample. In addition, we noticed that the radio-quiet and radio-loud AGNs have different power-law slopes in the radio-X-ray nonlinear relationship. The radio-loud sample displays a slope of 1.39, which seems consistent with the jet-dominated X-ray model. However, it may also be partly due to the relativistic beaming effect. For the radio-quiet sample the slope of the radio-X-ray relationship is about 0.85, which is possibly consistent with the theoretical prediction from the accretion-flow-dominated X-ray model. We briefly discuss the reason why our derived relationship is different from some previous works and expect the future spectral studies in radio and X-ray bands on individual sources in our sample to confirm our result.
664. Radio and X-ray-emitting broad-line AGNs
ID:
ivo://CDS.VizieR/J/ApJ/688/826
Title:
Radio and X-ray-emitting broad-line AGNs
Short Name:
J/ApJ/688/826
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use a recently released SDSS catalog of X-ray-emitting AGNs in conjunction with the FIRST radio survey to investigate the black hole (BH) fundamental plane relationship between the 1.4GHz radio luminosity (L_r_), 0.1-2.4keV X-ray luminosity (L_X_), and black hole mass (M), namely, logL_r_={xi}_RX_logL_X_+{xi}_RM_logM+constant. For this purpose, we compile a large sample of 725 broad-line AGNs, which consists of 498 radio-loud sources and 227 radio-quiet sources. We confirm that radio-loud objects have a steeper slope ({xi}_RX_) with respect to radio-quiet objects and that the dependence of the BH fundamental plane on the BH mass ({xi}_RM_) is weak.
665. Radio core dominance of Fermi/LAT-detected AGNs
ID:
ivo://CDS.VizieR/VIII/108
Title:
Radio core dominance of Fermi/LAT-detected AGNs
Short Name:
VIII/108
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a sample of 4388 AGNs with available radio core-dominance parameters-defined as the ratio of the core flux densities to the extended ones, R=S_core_/S_ext._ - which includes 630 Fermi-detected AGNs from the fourth source catalog (4FGL) of the Fermi Large Area Telescope (Fermi/LAT); the rest are non-Fermi-detected AGNs. In our sample, 584 blazars are Fermi-detected and 1310 are not. The sample also contains other subclasses, such as Seyferts, Fanaroff-Riley I/II galaxies, and normal galaxies. We investigate various properties of the Fermi-detected and non-Fermi-detected AGNs by using core-dominance parameters, capitalizing on a previous study which showed that R is a good indicator of beaming. We then calculate radio spectral indices for the whole sample, and adopt {gamma}-ray-photon indices for the Fermi AGNs from the 4FGL catalog to discuss the properties of different subclasses. We obtain a relation between the core-dominance parameters and the radio spectral indices for both Fermi and non-Fermi sources, assuming a two-component model in the radio band. Our previous study ruled out the assumption that the core-dominance parameters and radio spectral indices are quite different for different AGN subclasses. This holds not only for Fermi sources but also for non-Fermi sources. In particular, R is, on average, greater for the former AGNs than for the latter. In this study, we enlarge our sample with available values of R to 4388 AGNs, and the obtained conclusions are consistent with our previous study. We assume that the same two-component model holds for the {gamma}-ray band as for the radio band, and therefore, adopt the same relation between the core-dominance parameters and the {gamma}-ray-photon indices for Fermi AGNs. Our fitting results indicate that the {gamma}-ray emissions of Fermi blazars originate mainly from the jet, and therefore, we conclude that the Fermi blazars are beamed.
666. Radio-emitting AGN environmental prop.
ID:
ivo://CDS.VizieR/J/MNRAS/478/3848
Title:
Radio-emitting AGN environmental prop.
Short Name:
J/MNRAS/478/3848
Date:
10 Dec 2021 00:52:31
Publisher:
CDS
Description:
We study the environmental properties of z<=1.2 radio-selected active galactic nuclei (AGNs) belonging to the ~2deg^2^ of the COSMOS field, finding that about 20 per cent of them appear within overdense structures. AGNs with P_1.4GHz_>10^23.5^W/Hz/sr are twice more likely to be found in clusters with respect to fainter sources (~38 per cent vs ~15 per cent), just as radio-selected AGNs with stellar masses M_*_>10^11^M_{sun}_ are twice more likely to be found in overdense environments with respect to objects of lower mass (~24 per cent vs ~11 per cent). Comparisons with galaxy samples further suggest that radio-selected AGN of large stellar mass tend to avoid underdense environments more than normal galaxies with the same stellar content. Stellar masses also seem to determine the location of radio-active AGN within clusters: ~100 per cent of the sources found as satellite galaxies have M_*_<10^11.3^M_{sun}_, while ~100 per cent of the AGNs coinciding with a cluster central galaxy have M_*_>10^11^M_{sun}_. No different location within the cluster is instead observed for AGN of various radio luminosities. Radio AGN, which also emit in the Mid-Infrared show a marked preference to be found as isolated galaxies (~70 per cent) at variance with those also active in the X-ray that all seem to reside within overdensities. What emerges from our work is a scenario whereby physical processes on sub-pc and kpc scales (e.g. emission, respectively, related to the AGN and to star formation) are strongly interconnected with the large-scale environment of the AGN itself.
667. Radio galaxies and quasars
ID:
ivo://CDS.VizieR/J/A+A/303/420
Title:
Radio galaxies and quasars
Short Name:
J/A+A/303/420
Date:
21 Oct 2021
Publisher:
CDS
Description:
The simple unification scheme of powerful radio galaxies and quasars, based entirely on the orientation dependent effects, has been confronted with the observed radio structures for 152 radio galaxies and 173 steep spectrum quasars. Contrary to the scheme's prediction, the cosmological evolution of geometrical parameters describing the large scale structure of these two types of radio sources are different.
668. Radio galaxies in the 2dFGRS
ID:
ivo://CDS.VizieR/J/MNRAS/333/100
Title:
Radio galaxies in the 2dFGRS
Short Name:
J/MNRAS/333/100
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use redshift determinations and spectral analysis of galaxies in the 2dF Galaxy Redshift Survey (<VII/226>) to study the properties of local radio sources with S>=1mJy. 557 objects (hereafter called the spectroscopic sample) drawn from the FIRST survey(<VIII/71>) , corresponding to 2.3 per cent of the total radio sample, are found in the 2dFGRS catalogue within the area 9h 48min<=RA<=14h 32min and -2.77{deg}<=DE<=2.25{deg} (2000), down to a magnitude limit b_J_=19.45. The excellent quality of 2dF spectra allows us to divide these sources into classes, according to their optical spectra.
669. Radio/{gamma}-ray correlation in AGN
ID:
ivo://CDS.VizieR/J/ApJ/741/30
Title:
Radio/{gamma}-ray correlation in AGN
Short Name:
J/ApJ/741/30
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the active galactic nuclei (AGNs) detected by Fermi during its first year of operation, with the largest data sets ever used for this purpose. We use both archival interferometric 8.4GHz data (from the Very Large Array and ATCA, for the full sample of 599 sources) and concurrent single-dish 15GHz measurements from the Owens Valley Radio Observatory (OVRO, for a sub sample of 199 objects). Our unprecedentedly large sample permits us to assess with high accuracy the statistical significance of the correlation, using a surrogate data method designed to simultaneously account for common-distance bias and the effect of a limited dynamical range in the observed quantities.
670. Radio identification of EGRET sources
ID:
ivo://CDS.VizieR/J/ApJ/481/95
Title:
Radio identification of EGRET sources
Short Name:
J/ApJ/481/95
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a method to assess the reliability of the identification of EGRET sources with extragalactic radio sources. We verify that EGRET is detecting the blazar class of active galactic nuclei (AGNs). However many published identifications are found to be questionable. We provide a table of 42 blazars that we expect to be robust identifications of EGRET sources. This includes one previously unidentified EGRET source, the lensed AGN PKS 1830-210, near the direction of the Galactic center. We provide the best available positions for 16 more radio sources that are also potential identifications for previously unidentified EGRET sources. All high Galactic latitude EGRET sources (|b|>3) that demonstrate significant variability can be identified with flat-spectrum radio sources. This suggests that EGRET is not detecting any type of AGN other than blazars. This identification method has been used to establish with 99.998% confidence that the peak gamma-ray flux of a blazar is correlated with its average 5GHz radio flux. An even better correlation is seen between gamma-ray flux and the 2.29GHz flux density measured with VLBI at the base of the radio jet. Also, using high-confidence identifications, we find that the radio sources identified with EGRET sources have greater correlated VLBI flux densities than the parent population of flat radio spectrum sources.