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971. VSOP 5GHz AGN survey V.
ID:
ivo://CDS.VizieR/J/ApJS/175/314
Title:
VSOP 5GHz AGN survey V.
Short Name:
J/ApJS/175/314
Date:
21 Oct 2021
Publisher:
CDS
Description:
In 1997 February, the Japanese radio astronomy satellite HALCA was launched to provide the space-bourne element for the VLBI Space Observatory Program (VSOP) mission. Approximately 25% of the mission time was dedicated to the VSOP survey of bright compact active galactic nuclei (AGNs) at 5GHz. This paper, the fifth in the series, presents images and models for the remaining 140 sources not included in the third paper in the series, which contained 102 sources. For most sources, the plots of the (u,v) coverage, the visibility amplitude versus (u,v) distance, and the high-resolution image are presented. Model fit parameters to the major radio components are determined, and the brightness temperature of the core component for each source is calculated. The brightness temperature distributions for all of the sources in the VSOP AGN survey are discussed.
972. Warm IRAS sources. I. AGN candidates
ID:
ivo://CDS.VizieR/J/A+AS/70/95
Title:
Warm IRAS sources. I. AGN candidates
Short Name:
J/A+AS/70/95
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have previously shown that a blue (warm) 60 to 25{mu}m infrared colour provides a powerful parameter for discriminating between AGNs and normal galaxies and that the far-IR spectrum is therefore an efficient tool for finding new AGNs (de Grijp et al., 1985Natur.314..140D) Here we present a list of such AGN candidates based on warm IR sources from the IRAS Point Source Catalogue (PSC, Cat. II/125). Identification data and finding charts are also given. In addition the list of warm IRAS sources is supplemented by a compendium of data from the IRAS PSC on detected sources identified with previously known AGNs whose infrared spectra do not bring them within our colour selection criterion
973. Water maser data of 380 galaxies
ID:
ivo://CDS.VizieR/J/A+A/641/A162
Title:
Water maser data of 380 galaxies
Short Name:
J/A+A/641/A162
Date:
21 Oct 2021
Publisher:
CDS
Description:
Water megamaser emission at 22GHz has proven to be a powerful tool for astrophysical studies of active galactic nuclei (AGN) because it allows an accurate determination of the mass of the central black hole and of the accretion disc geometry and dynamics. However, after searches among thousands of galaxies, only ~200 of them have shown such spectroscopic features, most of them of uncertain classification. In addition, the physical and geometrical conditions under which a maser activates are still unknown. We characterize the occurrence of water maser emission in an unbiased sample of AGN by investigating the relation with the X-ray properties and the possible favourable geometry that is required to detect water maser. We searched for 22GHz maser emission in a hard X-ray selected sample of AGN, taken from the INTEGRAL/IBIS survey above 20keV. Only half of the 380 sources in the sample have water maser data. We also considered a volume-limited sub-sample of 87 sources, for which we obtained new observations with the Green Bank and Effelsberg telescopes (for 35 sources). We detected one new maser and increased its radio coverage to 75%. The detection rate of water maser emission in the total sample is 15+/-3%. This fraction increases to 19+/-5% for the complete sub-sample, especially when we consider type 2 (22+/-5% and 31+/-10% for the total and complete samples, respectively) and Compton-thick AGN (56+/-18% and 50+/-35% for the total and complete samples, respectively). No correlation is found between water maser and X-ray luminosity. We note that all types of masers (disc and jet) are associated with hard X-ray selected AGN. These results demonstrate that the hard X--ray selection may significantly enhance the maser detection efficiency over comparably large optical or infrared surveys. A possible decline in detection fraction with increasing luminosity might suggest that an extremely luminous nuclear environment does not favour maser emission. The large fraction of CT AGN with water maser emission could be explained in terms of geometrical effects. The maser medium would then be the very edge-on portion of the obscuring medium.
974. Water maser emission in five AGNs
ID:
ivo://CDS.VizieR/J/ApJ/652/136
Title:
Water maser emission in five AGNs
Short Name:
J/ApJ/652/136
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of water maser emission in five active galactic nuclei (AGNs) with the 100m Green Bank Telescope (GBT). The positions of the newly discovered masers, measured with the VLA, are consistent with the optical positions of the host nuclei to within 1{sigma} (0.3" radio and 1.3" optical) and most likely mark the locations of the embedded central engines. The spectra of three sources, 2MASX J08362280+3327383, NGC 6264, and UGC 09618 NED02 (PGC 053432), display the characteristic spectral signature of emission from an edge-on accretion disk with maximum orbital velocity of ~700, ~800, and ~1300km/s, respectively. We also present a GBT spectrum of a previously known source, Mrk 0034, and interpret the narrow Doppler components reported here as indirect evidence that the emission originates in an edge-on accretion disk with orbital velocity of ~500km/s .
975. WFC3/UVIS quasar-stacked spectrum at z=~2.4
ID:
ivo://CDS.VizieR/J/MNRAS/449/4204
Title:
WFC3/UVIS quasar-stacked spectrum at z=~2.4
Short Name:
J/MNRAS/449/4204
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ionizing continuum from active galactic nuclei is fundamental for interpreting their broad emission lines and understanding their impact on the surrounding gas. Furthermore, it provides hints on how matter accretes on to supermassive black holes. Using Hubble Space Telescope's Wide Field Camera 3, we have constructed the first stacked ultraviolet (rest-frame wavelengths 600-2500{AA}) spectrum of 53 luminous quasars at z=~2.4, with a state-of-the-art correction for the intervening Lyman forest and Lyman continuum absorption. The continuum slope (f_{nu}_{prop.to}{nu}^{alpha}{nu}^) of the full sample shows a break at ~912{AA} with spectral index {alpha}_{nu}_=-0.61+/-0.01 at {lambda}>912{AA} and a softening at shorter wavelengths ({alpha}_{nu}_=-1.70+/-0.61 at {lambda}<=912{AA}). Our analysis proves that a proper intergalactic medium absorption correction is required to establish the intrinsic continuum emission of quasars. We interpret our average ultraviolet spectrum in the context of photoionization, accretion disc models, and quasar contribution to the ultraviolet background. We find that observed broad line ratios are consistent with those predicted assuming an ionizing slope of {alpha}_ion_=-2.0, similar to the observed ionizing spectrum in the same wavelength range. The continuum break and softening are consistent with accretion disc plus X-ray corona models when black hole spin is taken into account. Our spectral energy distribution yields a 30 per cent increase to previous estimates of the specific quasar emissivity, such that quasars may contribute significantly to the total specific Lyman limit emissivity estimated from the Ly{alpha} forest at z<3.2.
976. Wide field ugriz photometry of 0.06<z<0.4 AGNs
ID:
ivo://CDS.VizieR/J/ApJ/800/93
Title:
Wide field ugriz photometry of 0.06<z<0.4 AGNs
Short Name:
J/ApJ/800/93
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present photometry of the large-scale environments of a sample of 12 broad line active galactic nuclei (AGNs) with 0.06<z<0.37 from deep images in the Sloan Digital Sky Survey u, g, r, and i filters taken with the 90Prime prime focus camera on the Steward Observatory Bok Telescope. We measure galaxy clustering around these AGNs using two standard techniques: correlation amplitude (B_gq_) and the two point correlation function. We find average correlation amplitudes for the 10 radio-quiet objects in the sample equal to (9+/-18, 144+/-114, -39+/-56, 295+/-260)Mpc^1.77^ in (u, g, r, i), all consistent with the expectation from galaxy clustering. Using a ratio of the galaxy-quasar cross-correlation function to the galaxy autocorrelation function, we calculate the relative bias of galaxies and AGNs, b_gq_. The bias in the u band, b_gq_=3.08+/-0.51 is larger compared to that calculated in the other bands, but it does not correlate with AGN luminosity, black hole mass, or AGN activity via the luminosity of the [OIII] emission line. Thus ongoing nuclear accretion activity is not reflected in the large scale environments from ~10h^-1^kpc to ~0.5h^-1^Mpc and may indicate a non-merger mode of AGN activity and/or a significant delay between galaxy mergers and nuclear activity in this sample of mostly radio-quiet quasars.
977. WISE and SDSS-DR7 data in 69 galaxy clusters
ID:
ivo://CDS.VizieR/J/ApJ/743/34
Title:
WISE and SDSS-DR7 data in 69 galaxy clusters
Short Name:
J/ApJ/743/34
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from a systematic study of star formation in local galaxy clusters using 22um data from the Wide-field Infrared Survey Explorer (WISE). The 69 systems in our sample are drawn from the Cluster Infall Regions Survey, and all have robust mass determinations. The all-sky WISE data enable us to quantify the amount of star formation, as traced by 22um, as a function of radius well beyond R_200_, and investigate the dependence of total star formation rate upon cluster mass. We find that the fraction of star-forming galaxies increases with cluster radius but remains below the field value even at 3R_200_. We also find that there is no strong correlation between the mass-normalized total specific star formation rate and cluster mass, indicating that the mass of the host cluster does not strongly influence the total star formation rate of cluster members.
978. WISE data for radio-loud AGN complete samples
ID:
ivo://CDS.VizieR/J/MNRAS/438/1149
Title:
WISE data for radio-loud AGN complete samples
Short Name:
J/MNRAS/438/1149
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an analysis of four complete samples of radio-loud active galactic nucleus (AGN; 3CRR, 2Jy, 6CE and 7CE) using near- and mid-IR data taken by the Wide-field Infrared Survey Explorer (WISE). The combined sample consists of 79 quasars and 273 radio galaxies, and covers a redshift range 0.003<z<3.395. The dichotomy in the mid-IR properties of low- and high-excitation radio galaxies (LERGs and HERGs) is analysed for the first time using large complete samples. Our results demonstrate that a division in the accretion modes of LERGs and HERGs clearly stands out in the mid-IR-radio plane (L_22{mu}m_=5x10^43^erg/s). This means that WISE data can be effectively used to diagnose accretion modes in radio-loud AGN. The mid-IR properties of all objects were analysed to test the unification between quasars and radio galaxies, consistent with earlier work, and we argue that smooth torus models best reproduce the observation. Quasars are found to have higher mid-IR luminosities than radio galaxies. We also studied all the sources in the near-IR to gain insights into evolution of AGN host galaxies. A relation found between the near-IR luminosity and redshift, well known in the near-IR, is apparent in the two near-IR WISE bands, supporting the idea that radio sources are hosted by massive elliptical galaxies that formed their stars at high redshifts and evolved passively thereafter. Evaluation of the positions of the sample objects in WISE colour-colour diagrams shows that widely used WISE colour cuts are not completely reliable in selecting AGN.
979. WMAP 3-yr sources at 16 and 33GHz
ID:
ivo://CDS.VizieR/J/MNRAS/400/984
Title:
WMAP 3-yr sources at 16 and 33GHz
Short Name:
J/MNRAS/400/984
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present follow-up observations of 97 point sources from the Wilkinson Microwave Anisotropy Probe (WMAP) 3-yr data, contained within the New Extragalactic WMAP Point Source catalogue between -4{deg}<=DE<=60{deg}; the sources form a flux-density-limited sample complete to 1.1Jy (~5{sigma}) at 33GHz. Our observations were made at 16GHz using the Arcminute Microkelvin Imager and at 33GHz with the Very Small Array (VSA).
980. WMAP 3-yr sources at 16 and 33GHz. II.
ID:
ivo://CDS.VizieR/J/MNRAS/400/995
Title:
WMAP 3-yr sources at 16 and 33GHz. II.
Short Name:
J/MNRAS/400/995
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the Arcminute Microkelvin Imager (AMI) at 16GHz and the Very Small Array (VSA) at 33GHz to make follow-up observations of sources in the New Extragalactic WMAP Point Source catalogue, we have investigated the flux density variability in a complete sample of 97 sources over time-scales of a few months to ~1.5yr.