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101. Catalog of strong MgII absorbers
ID:
ivo://CDS.VizieR/J/A+A/546/A67
Title:
Catalog of strong MgII absorbers
Short Name:
J/A+A/546/A67
Date:
21 Oct 2021
Publisher:
CDS
Description:
A significantly higher incidence of strong (rest equivalent width Wr>1{AA}) intervening MgII absorption is observed along gamma-ray burst (GRB) sight-lines relative to those of quasar sight-lines. A geometrical explanation for this discrepancy has been suggested: the ratio of the beam size of the source to the characteristic size of an MgII absorption system can influence the observed MgII equivalent width, if these two sizes are comparable. We investigate whether the differing beam sizes of the continuum source and broad-line region of Sloan Digital Sky Survey (SDSS) quasars produce a discrepancy between the incidence of strong MgII absorbers illuminated by the quasar continuum region and those of absorbers illuminated by both continuum and broad-line region light.
102. Catalog of variability selected AGNs in GOODS
ID:
ivo://CDS.VizieR/J/ApJ/723/737
Title:
Catalog of variability selected AGNs in GOODS
Short Name:
J/ApJ/723/737
Date:
21 Oct 2021
Publisher:
CDS
Description:
Variability is a property shared by practically all active galactic nuclei (AGNs). This makes variability selection a possible technique for identifying AGNs. Given that variability selection makes no prior assumption about spectral properties, it is a powerful technique for detecting both low-luminosity AGNs in which the host galaxy emission is dominating and AGNs with unusual spectral properties. In this paper, we will discuss and test different statistical methods for the detection of variability in sparsely sampled data that allow full control over the false positive rates. We will apply these methods to the GOODS North and South fields and present a catalog of variable sources in the z band in both GOODS fields. Out of the 11 931 objects checked, we find 155 variable sources at a significance level of 99.9%, corresponding to about 1.3% of all objects. After rejection of stars and supernovae, 139 variability-selected AGNs remain. Their magnitudes reach down as faint as 25.5mag in z. Spectroscopic redshifts are available for 22 of the variability-selected AGNs, ranging from 0.046 to 3.7. The absolute magnitudes in the rest-frame z band range from ~-18 to -24, reaching substantially fainter than the typical luminosities probed by traditional X-ray and spectroscopic AGN selection in these fields. Therefore, this is a powerful technique for future exploration of the evolution of the faint end of the AGN luminosity function up to high redshifts.
104. Catalogue of 1806 MgII absorbers from SDSS DR3
ID:
ivo://CDS.VizieR/J/MNRAS/371/495
Title:
Catalogue of 1806 MgII absorbers from SDSS DR3
Short Name:
J/MNRAS/371/495
Date:
21 Oct 2021
Publisher:
CDS
Description:
We measure the mean halo mass of z=~0.5 MgII absorbers using the cross-correlation (over comoving scales 0.05-13h^-1^Mpc) between 1806 MgII quasar absorption systems and ~250000 luminous red galaxies (LRGs), both selected from the Sloan Digital Sky Survey Data Release 3.
105. Catalogue of quasar candidates
ID:
ivo://CDS.VizieR/J/MNRAS/247/182
Title:
Catalogue of quasar candidates
Short Name:
J/MNRAS/247/182
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper gives a list of all quasar candidates obtained from an automated computer search performed on 11 grens plates. The description of the main characteristics of the survey is given along with the latest improvements in the selection techniques. Particular attention has been paid to understanding and quantifying selection effects. This allows the construction of homogeneous samples having well-understood characteristics. The noteworthy aspect of our homogenization process is the correction that we apply to our probability classes in order to take into account the signal-to-noise differences; at a given magnitude, among plates of different limiting magnitudes. Since such homogeneous material is rare, this catalogue is of general interest. Each grens plate covers about 1 square degree with typical limiting magnitude of B~21. Data are given with all relevant quantities needed to understand the characteristics of the survey. We expect that over 100 of the 125 higher probability class candidates are quasars. A third of the ~400 lower probability objects should also be quasars. This material is well-suited to follow-up spectroscopy with fibre spectrographs.
106. Catching the radio flare in CTA 102
ID:
ivo://CDS.VizieR/J/A+A/551/A32
Title:
Catching the radio flare in CTA 102
Short Name:
J/A+A/551/A32
Date:
21 Oct 2021
Publisher:
CDS
Description:
Very Long Baseline Interferometry (VLBI) observations can resolve the radio structure of active galactic nuclei (AGN) and provide estimates of the structural and kinematic characteristics on parsec-scales in their jets. The changes in the kinematics of the observed jet features can be used to study the physical conditions in the innermost regions of these sources. We performed multifrequency multiepoch Very Long Baseline Array (VLBA) observations of the blazar CTA102 during its 2006 radio flare, the strongest ever reported for this source. These observations provide an excellent opportunity to investigate the evolution of the physical properties of blazars, especially during these flaring events. We want to study the kinematic changes in the source during the strong radio outburst in April 2006 and test the assumption of a shock-shock interaction. This assumption is based on the analysis and modeling of the single-dish observations of CTA 102 (Paper I, 2011A&A...531A..95F). In this paper we study the kinematics of CTA 102 at several frequencies using VLBI observations. From the modeled jet features we derived estimates for the evolution of the physical parameters, such as the particle density and the magnetic field. Furthermore ,we combined our observations during the 2006 flare with long-term VLBA monitoring of the source at 15 GHz and 43 GHz We cross-identified seven features throughout our entire multifrequency observations and find evidence of two possible recollimation shocks around 0.1mas (deprojected 18pc at a viewing angle of 2.6{deg} and 6.0mas (deprojected 1kpc) from the core. The 43GHz observations reveal a feature ejected at epoch t_ej_=2005.9+/-0.2, which could be connected to the 2006 April radio flare. Furthermore, this feature might be associated with the traveling component involved in the possible shock-shock interaction, which gives rise to the observed double peak structure in the single-dish light curves reported in Paper I, 2011A&A...531A..95F.
107. Celestial Reference Frame at 24 and 43 GHz
ID:
ivo://CDS.VizieR/J/AJ/139/1695
Title:
Celestial Reference Frame at 24 and 43 GHz
Short Name:
J/AJ/139/1695
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present astrometric results for compact extragalactic objects observed with the Very Long Baseline Array at radio frequencies of 24 and 43GHz. Data were obtained from ten 24-hr observing sessions made over a five-year period. These observations were motivated by the need to extend the International Celestial Reference Frame (ICRF) to higher radio frequencies to enable improved deep space navigation after 2016 and to improve state-of-the-art astrometry. Source coordinates for 268 sources were estimated at 24GHz and for 131 sources at 43GHz.
108. Celestial Reference Frame at 24 and 43GHz. II
ID:
ivo://CDS.VizieR/J/AJ/139/1713
Title:
Celestial Reference Frame at 24 and 43GHz. II
Short Name:
J/AJ/139/1713
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have measured the submilliarcsecond structure of 274 extragalactic sources at 24 and 43 GHz in order to assess their astrometric suitability for use in a high-frequency celestial reference frame (CRF). Ten sessions of observations with the Very Long Baseline Array have been conducted over the course of ~5 years, with a total of 1339 images produced for the 274 sources. There are several quantities that can be used to characterize the impact of intrinsic source structure on astrometric observations including the source flux density, the flux density variability, the source structure index, the source compactness, and the compactness variability.
109. Census of QSOs Narrow Absorption Lines
ID:
ivo://CDS.VizieR/J/ApJS/171/1
Title:
Census of QSOs Narrow Absorption Lines
Short Name:
J/ApJS/171/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use Keck HIRES spectra of 37 optically bright quasars at z=2-4 to study narrow absorption lines that are intrinsic to the quasars (intrinsic NALs, produced in gas that is physically associated with the quasar central engine). We identify 150 NAL systems, which contain 124 CIV, 12 NV, and 50 SiIV doublets, of which 18 are associated systems (within 5000km/s of the quasar redshift). We use partial coverage analysis to separate intrinsic NALs from NALs produced in cosmologically intervening structures. We find 39 candidate intrinsic systems (28 reliable determinations and 11 that are possibly intrinsic). We estimate that 10%-17% of CIV systems at blueshifts of 5000-70000km/s relative to quasars are intrinsic. At least 32% of quasars contain one or more intrinsic CIV NALs. Considering NV and SiIV doublets showing partial coverage as well, at least 50% of quasars host intrinsic NALs.
110. CFH Blue Grens Quasar Candidates
ID:
ivo://CDS.VizieR/J/AJ/104/1706
Title:
CFH Blue Grens Quasar Candidates
Short Name:
J/AJ/104/1706
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)