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Start Over Subject active galactic nuclei
101. A search for double-peaked AGNs in AGES
ID:
ivo://CDS.VizieR/J/ApJ/777/64
Title:
A search for double-peaked AGNs in AGES
Short Name:
J/ApJ/777/64
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dual supermassive black holes (SMBHs) with kiloparsec-scale separations in merger-remnant galaxies are informative tracers of galaxy evolution, but the avenue for identifying them in large numbers for such studies is not yet clear. One promising approach is to target spectroscopic signatures of systems where both SMBHs are fueled as dual active galactic nuclei (AGNs), or where one SMBH is fueled as an offset AGN. Dual AGNs may produce double-peaked narrow AGN emission lines, while offset AGNs may produce single-peaked narrow AGN emission lines with line-of-sight velocity offsets relative to the host galaxy. We search for such dual and offset systems among 173 Type 2 AGNs at z<0.37 in the AGN and Galaxy Evolution Survey (AGES), and we find two double-peaked AGNs and five offset AGN candidates. When we compare these results to a similar search of the DEEP2 Galaxy Redshift Survey and match the two samples in color, absolute magnitude, and minimum velocity offset, we find that the fraction of AGNs that are dual SMBH candidates increases from z=0.25 to z=0.7 by a factor of ~6 (from 2/70 to 16/91, or 2.9_-1.9_^+3.6^% to 18_-5_^+5^%). This may be associated with the rise in the galaxy merger fraction over the same cosmic time. As further evidence for a link with galaxy mergers, the AGES offset and dual AGN candidates are tentatively ~3 times more likely than the overall AGN population to reside in a host galaxy that has a companion galaxy (from 16/173 to 2/7, or 9_-2_^+3^% to 29_-19_^+26^%). Follow-up observations of the seven offset and dual AGN candidates in AGES will definitively distinguish velocity offsets produced by dual SMBHs from those produced by narrow-line region kinematics, and will help sharpen our observational approach to detecting dual SMBHs.
102. ASKAP-EMU ESP LMC Radio Continuum Survey
ID:
ivo://CDS.VizieR/J/MNRAS/506/3540
Title:
ASKAP-EMU ESP LMC Radio Continuum Survey
Short Name:
J/MNRAS/506/3540
Date:
17 Jan 2022 11:54:41
Publisher:
CDS
Description:
We present an analysis of a new 120 deg^2^ radio continuum image of the Large Magellanic Cloud (LMC) at 888MHz with a bandwidth of 288MHz and beam size of 13.9"x12.1", from the Australian Square Kilometre Array Pathfinder (ASKAP) processed as part of the Evolutionary Map of the Universe (EMU) survey. The median Root Mean Squared noise is 58uJy/beam. We present a catalogue of 54612 sources, divided over a Gold list (30866 sources) complete down to 0.5mJy uniformly across the field, a Silver list (22080 sources) reaching down to <0.2mJy and a Bronze list (1666 sources) of visually inspected sources in areas of high noise and/or near bright complex emission. We discuss detections of planetary nebulae and their radio luminosity function, young stellar objects showing a correlation between radio luminosity and gas temperature, novae and X-ray binaries in the LMC, and active stars in the Galactic foreground that may become a significant population below this flux level. We present examples of diffuse emission in the LMC (HII regions, supernova remnants, bubbles) and distant galaxies showcasing spectacular interaction between jets and intracluster medium. Among 14333 infrared counterparts of the predominantly background radio source population we find that star-forming galaxies become more prominent below 3mJy compared to active galactic nuclei.We combine the new 888MHz data with archival Australia Telescope Compact Array data at 1.4GHz to determine spectral indices; the vast majority display synchrotron emission but flatter spectra occur too. We argue that the most extreme spectral index values are due to variability.
103. Associations to 1FGL sources
ID:
ivo://CDS.VizieR/J/ApJ/753/83
Title:
Associations to 1FGL sources
Short Name:
J/ApJ/753/83
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Fermi Large Area Telescope (LAT) First Source Catalog (1FGL) provided spatial, spectral, and temporal properties for a large number of {gamma}-ray sources using a uniform analysis method. After correlating with the most-complete catalogs of source types known to emit {gamma} rays, 630 of these sources are "unassociated" (i.e., have no obvious counterparts at other wavelengths). Here, we employ two statistical analyses of the primary {gamma}-ray characteristics for these unassociated sources in an effort to correlate their {gamma}-ray properties with the active galactic nucleus (AGN) and pulsar populations in 1FGL. Based on the correlation results, we classify 221 AGN-like and 134 pulsar-like sources in the 1FGL unassociated sources. The results of these source "classifications" appear to match the expected source distributions, especially at high Galactic latitudes. While useful for planning future multiwavelength follow-up observations, these analyses use limited inputs, and their predictions should not be considered equivalent to "probable source classes" for these sources. We discuss multiwavelength results and catalog cross-correlations to date, and provide new source associations for 229 Fermi-LAT sources that had no association listed in the 1FGL catalog. By validating the source classifications against these new associations, we find that the new association matches the predicted source class in ~80% of the sources.
104. Astrometric Catalogue 5, LQAC-5
ID:
ivo://CDS.VizieR/J/A+A/624/A145
Title:
Astrometric Catalogue 5, LQAC-5
Short Name:
J/A+A/624/A145
Date:
21 Oct 2021
Publisher:
CDS
Description:
In addition to their great astrophysical interest, quasars represent quasi-ideal reference objects in the celestial sphere with, a priori, a lack of significant proper motion. Since the fourth release of the Large Quasar Astrometric Catalogue (LQAC-4), a large number of quasars have been discovered, in particular those coming from the DR14Q release of the SDSS. With the advent of the Gaia Data Release 2 (DR2), it is now also possible to fold in extremely accurate quasar positions. Following the same procedure as in the previous releases of the LQAC, our aim is to compile the large majority of the recorded quasars, with their best estimated coordinates and substantial information about their physical properties such as the redshift, multi-bands apparent, and absolute magnitudes. Emphasis is given to the results of the cross-matches with the Gaia DR2 catalogue, which considerably increases the positional accuracy. New quasars from the SDSS DR14Q release were cross-matched with the precedent LQAC-4 compilation with a 1" search radius, which leads to 149084 objects not present in the previous LQAC-4 release. Another cross-match was done with the Gaia DR2 catalogue, which enables us to considerably improve the positioning of these objects. For the first time, parallaxes and proper motions from the DR2, when available, are added to our compilation. Furthermore, a cross-identification of the LQAC-5 with the AllWISE survey gives additional mid-infrared information for an important percentage of objects. Our final catalogue, namely the LQAC-5, contains 592 809 quasars. This represents roughly a 34% increase with respect to the number of objects recorded in the LQAC-4. Among them, 398 697 objects were found in common with the Gaia DR2, within a 1" search radius. That corresponds to 67.26% of the whole population of the compilation. The LQAC-5 delivers a nearly complete catalogue of spectroscopically confirmed quasars (including a small proportion of 14126 compact AGN's) to the astronomical community, with the aim of giving their best equatorial coordinates with respect to the ICRF2 and with exhaustive additional information. For more than 50% of the sample, these coordinates are extracted from the very recent Gaia DR2.
105. Astrometric classification of 647 VLBI sources
ID:
ivo://CDS.VizieR/J/A+A/618/A80
Title:
Astrometric classification of 647 VLBI sources
Short Name:
J/A+A/618/A80
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the result of our Allan standard deviation based classification according to their astrometric stability. The classification is divided into three categories (stable sources, intermediate sources, unstable sources). Stability of sources is qualified by the astrometric behavior of the source. This determines in which category the source falls into. Then, stability of the source is also quantified by a stability index (two are proposed in the table). Those indexes enable to order sources in each category of the classification.
106. ATCA 18.5 and 22GHz fluxes of Kuehr 5GHz sample
ID:
ivo://CDS.VizieR/J/A+A/445/465
Title:
ATCA 18.5 and 22GHz fluxes of Kuehr 5GHz sample
Short Name:
J/A+A/445/465
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss our ATCA 18.5 and 22GHz flux density measurements of Southern extragalactic sources in the complete 5GHz sample of Kuehr et al. (1981, Cat. <VIII/5>). The high frequency (5-18.5GHz) spectral indices of steep-spectrum sources for which we have 18.5GHz data (66% of the complete sample) are systematically steeper than the low frequency (2.7-5GHz) ones, and there is evidence of an anti-correlation of high-frequency spectral index with luminosity. The completeness of 18.5GHz data is much higher (89%) for flat-spectrum sources (mostly quasars), which also exhibit a spectral steepening. Taking advantage of the almost complete redshift information on flat-spectrum quasars, we have estimated their 5GHz luminosity function in several redshift bins. The results confirm that their radio luminosity density peaks at z_peak about 2.5 but do not provide evidence for deviations from pure luminosity evolution as hinted at by other data sets. A comparison of our 22GHz flux densities with WMAP K-band data for flat-spectrum sources suggests that WMAP flux densities may be low by a median factor of about 1.2. The extrapolations of 5GHz counts and luminosity functions of flat-spectrum radio quasars using the observed distribution of the 5-18.5GHz spectral indices match those derived directly from WMAP data, indicating that the high frequency WMAP survey does not detect any large population of FSRQs with anomalous spectra.
107. ATCA observations of 202 compact radio sources
ID:
ivo://CDS.VizieR/J/PASJ/55/351
Title:
ATCA observations of 202 compact radio sources
Short Name:
J/PASJ/55/351
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Australia Telescope Compact Array (ATCA) has been used in support of the VLBI Space Observatory Programme (VSOP) space VLBI mission, to monitor the total and polarised flux densities of 202 objects that make up 83% of the VSOP all-sky Survey of compact extragalactic radio sources south of DE=+10{deg}. The primary goal of the ATCA observations is to provide information on the total and polarised emission from the compact components in these sources, for correlation with parameters obtained from VSOP imaging observations. These data represent the first high resolution, long timescale flux density monitoring observations of a large number of southern compact radio sources. In the future, comparison of the ATCA and VSOP data will be used to investigate relativistic beaming models and identify similarities or differences between the major classes of extragalactic radio sources. As an illustration of the scientific value of the ATCA data we undertake a comparison of the properties of the gamma-ray loud and gamma-ray quiet AGN in the southern component of the VSOP Survey sample, finding that in a flat-spectrum sub-sample the gamma-ray loud AGN are more variable than the gamma-ray quiet AGN.
108. ATLAS 2.3GHz observations of ELAIS-S1 and CDF-S
ID:
ivo://CDS.VizieR/J/A+A/544/A38
Title:
ATLAS 2.3GHz observations of ELAIS-S1 and CDF-S
Short Name:
J/A+A/544/A38
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Australia Telescope Large Area Survey (ATLAS) aims to image a 7deg^2^ region centred on the European Large Area ISO Survey - South 1 (ELAIS-S1) field and the Chandra Deep Field South (CDF-S) at 1.4GHz with high sensitivity (up to {sigma}~10uJy) to study the evolution of star-forming galaxies (SFGs) and Active Galactic Nuclei (AGN) over a wide range of cosmic time. We present here ancillary radio observations at a frequency of 2.3GHz obtained with the Australia Telescope Compact Array (ATCA). The main goal of this is to study the radio spectra of an unprecedented large sample of sources (~2000 observed, ~600 detected in both frequencies).
109. Atlas of warm AGN and starbursts
ID:
ivo://CDS.VizieR/J/ApJS/158/139
Title:
Atlas of warm AGN and starbursts
Short Name:
J/ApJS/158/139
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a set of 180 active galactic nucleus (AGN) candidates based on color selection from the IRAS slow-scan deep observations, with color criteria broadened from the initial Point Source Catalog (Cat. <II/125>) samples so as to include similar objects with redshifts up to z=1 and allowing for two-band detections. Spectroscopic identifications have been obtained for 80 (44%); some additional identifications are secure based on radio detections or optical morphology, although yet unobserved spectroscopically. These spectroscopic identifications include 13 type-1 Seyfert galaxies, 17 type-2 Seyferts, 29 starburst galaxies, 7 LINER systems, and 13 emission-line galaxies so heavily reddened as to remain of ambiguous classification.
110. ATLAS radio observations of ELAIS-S1
ID:
ivo://CDS.VizieR/J/AJ/135/1276
Title:
ATLAS radio observations of ELAIS-S1
Short Name:
J/AJ/135/1276
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have conducted sensitive (1{sigma}<30uJy) 1.4GHz radio observations with the Australia Telescope Compact Array of a field largely coincident with infrared observations of the Spitzer Wide-Area Extragalactic Survey (SWIRE, 2003PASP..115..897L). The field is centered on the European Large Area ISO Survey S1 region and has a total area of 3.9{deg}. We describe the observations and calibration, source extraction, and cross-matching to infrared sources. Two catalogs are presented: one of the radio components found in the image and another of radio sources with counterparts in the infrared and extracted from the literature. 1366 radio components were grouped into 1276 sources, 1183 of which were matched to infrared sources. We discover 31 radio sources with no infrared counterpart at all, adding to the class of Infrared-Faint Radio Sources.