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861. SED of QSO J1120+064 (ULAS J112001.48+064124.3)
ID:
ivo://CDS.VizieR/J/A+A/575/A31
Title:
SED of QSO J1120+064 (ULAS J112001.48+064124.3)
Short Name:
J/A+A/575/A31
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new observations of the highest-redshift quasar known, ULAS J1120+0641, redshift z=7.084, obtained in the optical, at near-, mid-, and far-infrared wavelengths, and in the sub-mm. We combine these results with published X-ray and radio observations to create the multiwavelength spectral energy distribution (SED), with the goals of measuring the bolometric luminosity Lbol, and quantifying the respective contributions from the AGN and star formation. We
862. SED of Spitzer quasars (QUEST)
ID:
ivo://CDS.VizieR/J/ApJ/666/806
Title:
SED of Spitzer quasars (QUEST)
Short Name:
J/ApJ/666/806
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the second paper studying the QSOs in the Spitzer QUEST sample. Previously we presented new PAH measurements and argued that most of the observed far-infrared (FIR) radiation is due to star-forming activity. Here we present spectral energy distributions (SEDs) by supplementing our data with optical, NIR, and FIR observations. We define two subgroups, of "weak FIR" and "strong FIR" QSOs, and a third group of FIR nondetections. Assuming a starburst origin for the FIR, we obtain "intrinsic" active galactic nucleus (AGN) SEDs by subtracting a starburst template from the mean SEDs. The resulting SEDs are remarkably similar for all groups.
863. SED of the Fermi blazars
ID:
ivo://CDS.VizieR/J/ApJ/709/1407
Title:
SED of the Fermi blazars
Short Name:
J/ApJ/709/1407
Date:
21 Oct 2021
Publisher:
CDS
Description:
We complied the optical, X-ray, and {gamma}-ray data for 54 Fermi blazars and studied the relationship between the broadband spectral index {alpha}_ox_ and {alpha}_x{gamma}_, as well as the relationship between the intrinsic composite spectral indices {alpha}_xox_ and {alpha}_{gamma}x{gamma}_ for this sample. The relationship between {alpha}_xox_ and {alpha}_{gamma}x{gamma}_ reveals that flat spectrum radio quasars and low-energy peaked BL Lacertae follow a continuous trend, which is consistent with previous results, whereas high-energy peaked BL Lacertae follow a separate distinct trend. Even so, a unified scheme is also revealed from {alpha}_xox_-{alpha}_{gamma}x{gamma}_ diagram when all three subclasses of blazars are considered.
864. SEDs of type I AGN in XMM-COSMOS. II.
ID:
ivo://CDS.VizieR/J/MNRAS/438/1288
Title:
SEDs of type I AGN in XMM-COSMOS. II.
Short Name:
J/MNRAS/438/1288
Date:
21 Oct 2021
Publisher:
CDS
Description:
The mid-infrared-to-ultraviolet (0.1-10{mu}m) spectral energy distribution (SED) shapes of 407 X-ray-selected radio-quiet type 1 active galactic nuclei (AGN) in the wide-field 'Cosmic Evolution Survey' (COSMOS) have been studied for signs of evolution. For a sub-sample of 200 radio-quiet quasars with black hole mass estimates and host galaxy corrections, we studied their mean SEDs as a function of a broad range of redshift, bolometric luminosity, black hole mass and Eddington ratio, and compared them with the Elvis et al. (1994ApJS...95....1E, Cat. J/ApJS/95/1, hereafter E94) type 1 AGN mean SED. We found that the mean SEDs in each bin are closely similar to each other, showing no statistical significant evidence of dependence on any of the analysed parameters. We also measured the SED dispersion as a function of these four parameters, and found no significant dependences. The dispersion of the XMM-COSMOS SEDs is generally larger than E94 SED dispersion in the ultraviolet, which might be due to the broader 'window function' for COSMOS quasars, and their X-ray-based selection.
865. S5 0836+710 Ground and Space VLBI images
ID:
ivo://CDS.VizieR/J/A+A/641/A40
Title:
S5 0836+710 Ground and Space VLBI images
Short Name:
J/A+A/641/A40
Date:
21 Oct 2021
Publisher:
CDS
Description:
Detailed studies of relativistic jets in active galactic nuclei (AGN) require high-fidelity imaging at the highest possible resolution. This can be achieved using very long baseline interferometry (VLBI) at radio frequencies, combining worldwide (global) VLBI arrays of radio telescopes with a space-borne antenna on board a satellite. We present multiwavelength images made of the radio emission in the powerful quasar S5 0836+710, obtained using a global VLBI array and the antenna Spektr-R of the RadioAstron mission of the Russian Space Agency, with the goal of studying the internal structure and physics of the relativistic jet in this object. The RadioAstron observations at wavelengths of 18cm, 6cm, and 1.3cm are part of the Key Science Program for imaging radio emission in strong AGN. The internal structure of the jet is studied by analyzing transverse intensity profiles and modeling the structural patterns developing in the flow. The RadioAstron images reveal a wealth of structural detail in the jet of S5 0836+710 on angular scales ranging from 0.02mas to 200mas. Brightness temperatures in excess of 10^13^K are measured in the jet, requiring Doppler factors of >=100 for reconciling them with the inverse Compton limit. Several oscillatory patterns are identified in the ridge line of the jet and can be explained in terms of the Kelvin-Helmholtz (KH) instability. The oscillatory patterns are interpreted as the surface and body wavelengths of the helical mode of the KH instability. The interpretation provides estimates of the jet Mach number and of the ratio of the jet to the ambient density, which are found to be Mj~=12 and {eta}~=0.33. The ratio of the jet to the ambient density should be conservatively considered an upper limit because its estimate relies on approximations.
866. SiIV absorption systems
ID:
ivo://CDS.VizieR/J/ApJ/729/87
Title:
SiIV absorption systems
Short Name:
J/ApJ/729/87
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identified 24 SiIV absorption systems with z<~1 from a blind survey of 49 low-redshift quasars with archival Hubble Space Telescope ultraviolet spectra. We relied solely on the characteristic wavelength separation of the doublet to automatically detect candidates. After visual inspection, we defined a sample of 20 definite (group G=1) and 4 "highly likely" (G=2) doublets with rest equivalent widths W_r_ for both lines detected at >=3{sigma}_W_r__.
867. SiIV and NV absorption line SDSS quasar systems
ID:
ivo://CDS.VizieR/J/ApJS/243/2
Title:
SiIV and NV absorption line SDSS quasar systems
Short Name:
J/ApJS/243/2
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the quasar spectra from the Sloan Digital Sky Survey and with variable C IV absorption line systems, we measure the Si IV and N V absorption line systems. We obtain 50 variable Si IV absorption line systems and 39 variable N V absorption line systems. We find that the variations in most of the C IV, Si IV, and N V absorption lines are correlated with the changes in quasar continuum. In addition, a significant portion of the variable absorption lines are the consistent variations of multiple systems with large velocity separations. Therefore, the variations of the C IV, Si IV, and N V absorption lines could be mainly driven by the changes in quasar radiations, which cause changes in ionization states or column densities of absorbing gas. We also find that the variable C IV, Si IV, and N V absorption line systems can be divided into low-ionization systems and high-ionization systems. The former positively responds to the changes in the quasar's brightness, and the later is the oppositive case.
868. S5 0836+710 image at 1.6GHz
ID:
ivo://CDS.VizieR/J/A+A/545/A65
Title:
S5 0836+710 image at 1.6GHz
Short Name:
J/A+A/545/A65
Date:
21 Oct 2021
Publisher:
CDS
Description:
The remarkable stability of extragalactic jets is surprising, given the reasonable possibility of the growth of instabilities. In addition, much work in the literature has invoked this possibility to explain observed jet structures and obtain information about the jet from these structures. For example, it has been shown that the observed helical structures in the jet in S5 0836+710 could be associated with helical pressure waves generated by a Kelvin-Helmholtz instability. Our aim is to resolve the arc-second structure of the jet in the quasar S5 0836+710 and confirm the lack of a hot-spot (reverse jet-shock) found by present observing arrays, as this lack implies a loss of jet collimation before interaction with the intergalactic medium.
869. Sizes of MRC radio galaxies and QSOs
ID:
ivo://CDS.VizieR/J/ApJ/766/37
Title:
Sizes of MRC radio galaxies and QSOs
Short Name:
J/ApJ/766/37
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the currently popular orientation-based unified scheme, a radio galaxy appears as a quasar when its principal radio-axis happens to be oriented within a certain cone opening angle around the observer's line of sight. Due to geometrical projection, the observed sizes of quasars should therefore appear smaller than those of radio galaxies. We show that this simple, unambiguous prediction of the unified scheme is not borne out by the actually observed angular sizes of radio galaxies and quasars. Except in the original 3CR sample, based on which the unified scheme was proposed, in other much larger samples no statistically significant difference is apparent in the size distributions of radio galaxies and quasars. The population of low-excitation radio galaxies with apparently no hidden quasars inside, which might explain the observed excess number of radio galaxies at low redshifts, cannot account for the absence of any foreshortening of the sizes of quasars at large redshifts. On the other hand, from infrared and X-ray studies, there is evidence of a hidden quasar within a dusty torus in many radio galaxies, at z>0.5. It is difficult to reconcile this with the absence of foreshortening of quasar sizes at even these redshifts, and perhaps one has to allow that the major radio axis may not have anything to do with the optical axis of the torus. Otherwise, to resolve the dichotomy of radio galaxies and quasars, a scheme quite different from the present might be required.
870. Sloan Digital Sky Survey quasar photometry
ID:
ivo://CDS.VizieR/J/AJ/121/2308
Title:
Sloan Digital Sky Survey quasar photometry
Short Name:
J/AJ/121/2308
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an empirical investigation of the colors of quasars in the Sloan Digital Sky Survey (SDSS) photometric system. The sample studied includes 2625 quasars with SDSS photometry: 1759 quasars found during SDSS spectroscopic commissioning and SDSS follow-up observations on other telescopes, 50 matches to FIRST quasars, 573 matches to quasars from the NASA Extragalactic Database, and 243 quasars from two or more of these sources. The quasars are distributed in a 2.5{deg} wide stripe centered on the celestial equator covering ~529deg^2^. Positions (accurate to 0.2") and SDSS magnitudes are given for the 898 quasars known prior to SDSS spectroscopic commissioning.

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