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501. Millimeter continuum of extragal. sources III.
ID:
ivo://CDS.VizieR/J/A+AS/102/611
Title:
Millimeter continuum of extragal. sources III.
Short Name:
J/A+AS/102/611
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
502. MiNDSTEP Danish Observatory Lens Images
ID:
ivo://org.gavo.dc/danish/red/data
Title:
MiNDSTEP Danish Observatory Lens Images
Short Name:
danish.data
Date:
27 Dec 2024 08:31:01
Publisher:
The GAVO DC team
Description:
TBD
503. MIR-selected quasar parameters
ID:
ivo://CDS.VizieR/J/ApJ/791/113
Title:
MIR-selected quasar parameters
Short Name:
J/ApJ/791/113
Date:
21 Oct 2021
Publisher:
CDS
Description:
We provide a catalog of 391 mid-infrared-selected (MIR; 24 {mu}m) broad-emission-line (BEL; type 1) quasars in the 22 deg^2^ SWIRE Lockman Hole field. This quasar sample is selected in the MIR from Spitzer MIPS with S_24_> 400 {mu}Jy, jointly with an optical magnitude limit of r(AB) < 22.5 for broad line identification. The catalog is based on MMT and Sloan Digital Sky Survey (SDSS) spectroscopy to select BEL quasars, extending the SDSS coverage to fainter magnitudes and lower redshifts, and recovers a more complete quasar population. The MIR-selected quasar sample peaks at z ~ 1.4 and recovers a significant and constant (20%) fraction of extended objects with SDSS photometry across magnitudes, which were not included in the SDSS quasar survey dominated by point sources. This sample also recovers a significant population of z < 3 quasars at i > 19.1. We then investigate the continuum luminosity and line profiles of these MIR quasars, and estimate their virial black hole masses and the Eddington ratios. The supermassive black hole mass shows evidence of downsizing, although the Eddington ratios remain constant at 1 < z < 4. Compared to point sources in the same redshift range, extended sources at z < 1 show systematically lower Eddington ratios. The catalog and spectra are publicly available online.
504. mm-monitoring of radio sources IV.
ID:
ivo://CDS.VizieR/J/A+AS/122/271
Title:
mm-monitoring of radio sources IV.
Short Name:
J/A+AS/122/271
Date:
21 Oct 2021
Publisher:
CDS
Description:
Radio flux densities are presented for 118 extragalactic radio sources monitored at 90, 142 and 230GHz with the IRAM 30m telescope during 1993-1994. For the most frequently observed sources we show light curves including 30 m-measurements published in previous papers, Steppe et al. (1988A&AS...75..317S; 1992A&AS...96..441S and and 1993, Cat. <J/A+AS/102/611>)
505. 7mm spectral survey of PKS 1830-211
ID:
ivo://CDS.VizieR/J/A+A/535/A103
Title:
7mm spectral survey of PKS 1830-211
Short Name:
J/A+A/535/A103
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a wide 7mm spectral survey of molecular absorption lines arising in the disk of a z=0.89 spiral galaxy located in front of the quasar PKS 1830-211. The survey was done with the Australia Telescope Compact Array and covers the frequency interval 30-50GHz, corresponding to the rest-frame frequency interval 57-94GHz. A total of 28 different species, plus 8 isotopic variants, were detected toward the South-West absorption, located at about 2kpc from the center of the z=0.89 galaxy, which makes it the extragalactic object with the largest number of detected molecular species so far.
506. MOJAVE IX. Core shift effects
ID:
ivo://CDS.VizieR/J/A+A/545/A113
Title:
MOJAVE IX. Core shift effects
Short Name:
J/A+A/545/A113
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have investigated a frequency-dependent shift in the absolute position of the optically thick apparent origin of parsec-scale jets ("core shift" effect) to probe physical conditions in ultra-compact relativistic outflows in active galactic nuclei. We used multi-frequency Very Long Baseline Array (VLBA) observations of 191 sources carried out in 12 epochs in 2006 within the Monitoring Of Jets in Active galactic nuclei with VLBA Experiments (MOJAVE) program. The observations were performed at 8.1, 8.4, 12.1, and 15.4GHz. We implemented a method of determining the core shift vector based on (i) image registration by two-dimensional normalized cross-correlation and (ii) model-fitting the source brightness distribution to take into account a non-zero core component offset from the phase center.
507. MOJAVE VII. Blazar jet acceleration
ID:
ivo://CDS.VizieR/J/ApJ/706/1253
Title:
MOJAVE VII. Blazar jet acceleration
Short Name:
J/ApJ/706/1253
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss acceleration measurements for a large sample of extragalactic radio jets from the Monitoring Of Jets in Active Galactic Nuclei with VLBA Experiments (MOJAVE) program, which studies the parsec-scale jet structure and kinematics of a complete, flux-density-limited sample of active galactic nuclei (AGNs). Accelerations are measured from the apparent motion of individual jet features or "components" which may represent patterns in the jet flow. We find that significant accelerations are common both parallel and perpendicular to the observed component velocities.
508. MOJAVE. VIII. Faraday rotation in AGN jets.
ID:
ivo://CDS.VizieR/J/AJ/144/105
Title:
MOJAVE. VIII. Faraday rotation in AGN jets.
Short Name:
J/AJ/144/105
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report observations of Faraday rotation measures for a sample of 191 extragalactic radio jets observed within the MOJAVE program. Multifrequency Very Long Baseline Array observations were carried out over 12 epochs in 2006 at four frequencies between 8 and 15GHz. We detect parsec-scale Faraday rotation measures in 149 sources and find the quasars to have larger rotation measures on average than BL Lac objects. The median core rotation measures are significantly higher than in the jet components. This is especially true for quasars where we detect a significant negative correlation between the magnitude of the rotation measure and the de-projected distance from the core. We perform detailed simulations of the observational errors of total intensity, polarization, and Faraday rotation, and concentrate on the errors of transverse Faraday rotation measure gradients in unresolved jets. Our simulations show that the finite image restoring beam size has a significant effect on the observed rotation measure gradients, and spurious gradients can occur due to noise in the data if the jet is less than two beams wide in polarization. We detect significant transverse rotation measure gradients in four sources (0923+392, 1226+023, 2230+114, and 2251+158). In 1226+023 the rotation measure is for the first time seen to change sign from positive to negative over the transverse cuts, which supports the presence of a helical magnetic field in the jet. In this source we also detect variations in the jet rotation measure over a timescale of three months, which are difficult to explain with external Faraday screens and suggest internal Faraday rotation. By comparing fractional polarization changes in jet components between the four frequency bands to depolarization models, we find that an external purely random Faraday screen viewed through only a few lines of sight can explain most of our polarization observations, but in some sources, such as 1226+023 and 2251+158, internal Faraday rotation is needed.
509. MOJAVE. VI. Kinematic analysis of blazar jets
ID:
ivo://CDS.VizieR/J/AJ/138/1874
Title:
MOJAVE. VI. Kinematic analysis of blazar jets
Short Name:
J/AJ/138/1874
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss the jet kinematics of a complete flux-density-limited sample of 135 radio-loud active galactic nuclei (AGNs) resulting from a 13 year program to investigate the structure and evolution of parsec-scale jet phenomena. Our analysis is based on new 2cm Very Long Baseline Array (VLBA) images obtained between 2002 and 2007, but includes our previously published observations made at the same wavelength, and is supplemented by VLBA archive data. In all, we have used 2424 images spanning the years 1994-2007 to study and determine the motions of 526 separate jet features in 127 jets.
510. MOJAVE. XII. Acceleration of blazar jets
ID:
ivo://CDS.VizieR/J/ApJ/798/134
Title:
MOJAVE. XII. Acceleration of blazar jets
Short Name:
J/ApJ/798/134
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on the acceleration properties of 329 features in 95 blazar jets from the MOJAVE Very Long Baseline Array program. Nearly half the features and three-quarters of the jets show significant changes in speed and/or direction. In general, apparent speed changes are distinctly larger than changes in direction, indicating that changes in the Lorentz factors of jet features dominate the observed speed changes rather than bends along the line of sight. Observed accelerations tend to increase the speed of features near the jet base, <~10-20pc projected, and decrease their speed at longer distances. The range of apparent speeds at a fixed distance in an individual jet can span a factor of a few, indicating that shock properties and geometry may influence the apparent motions; however, we suggest that the broad trend of jet features increasing their speed near the origin is due to an overall acceleration of the jet flow out to deprojected distances of the order of 10^2^pc, beyond which the flow begins to decelerate or remains nearly constant in speed. We estimate intrinsic rates of change of the Lorentz factors in the galaxy frame of the order of {sdot}{Gamma}/{Gamma}~=10^-3^ to 10^-2^/yr, which can lead to total Lorentz factor changes of a factor of a few on the length scales observed here. Finally, we also find evidence for jet collimation at projected distances of <~10pc in the form of the non-radial motion and bending accelerations that tend to better align features with the inner jet.