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851. Second epoch VLBA Calibrator Survey (VCS-II)
ID:
ivo://CDS.VizieR/J/AJ/151/154
Title:
Second epoch VLBA Calibrator Survey (VCS-II)
Short Name:
J/AJ/151/154
Date:
21 Oct 2021
Publisher:
CDS
Description:
Six very successful Very Long Baseline Array (VLBA) calibrator survey campaigns were run between 1994 and 2007 to build up a large list of compact radio sources with positions precise enough for use as very long baseline interferometry (VLBI) phase reference calibrators. We report on the results of a second epoch VLBA Calibrator Survey campaign (VCS-II) in which 2400 VCS sources were re-observed in the X and S bands in order to improve the upcoming third realization of the International Celestial Reference Frame (ICRF3) as well as to improve their usefulness as VLBI phase reference calibrators. In this survey, some 2062 previously detected sources and 324 previously undetected sources were detected and revised positions are presented. Average position uncertainties for the re-observed sources were reduced from 1.14 and 1.98mas to 0.24 and 0.41mas in R.A. and decl., respectively, or by nearly a factor of 5. Minimum detected flux values were approximately 15 and 28mJy in the X and S bands, respectively, and median total fluxes are approximately 230 and 280mJy. The vast majority of these sources are flat-spectrum sources, with ~82% having spectral indices greater than -0.5.
852. SED and bolometric corrections for luminous QSOs
ID:
ivo://CDS.VizieR/J/ApJS/206/4
Title:
SED and bolometric corrections for luminous QSOs
Short Name:
J/ApJS/206/4
Date:
21 Oct 2021
Publisher:
CDS
Description:
We explore the mid-infrared (mid-IR) through ultraviolet (UV) spectral energy distributions (SEDs) of 119652 luminous broad-lined quasars with 0.064<z<5.46 using mid-IR data from Spitzer and WISE, near-infrared data from the Two Micron All Sky Survey and UKIDSS, optical data from the Sloan Digital Sky Survey, and UV data from the Galaxy Evolution Explorer. The mean SED requires a bolometric correction (relative to 2500{AA}) of BC_2500{AA}_=2.75+/-0.40 using the integrated light from 1um-2keV, and we further explore the range of bolometric corrections exhibited by individual objects. In addition, we investigate the dependence of the mean SED on various parameters, particularly the UV luminosity for quasars with 0.5<~z<~3 and the properties of the UV emission lines for quasars with z>~1.6; the latter is a possible indicator of the strength of the accretion disk wind, which is expected to be SED-dependent.
853. SED of Fermi bright blazars
ID:
ivo://CDS.VizieR/J/ApJ/716/30
Title:
SED of Fermi bright blazars
Short Name:
J/ApJ/716/30
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have conducted a detailed investigation of the broadband spectral properties of the {gamma}-ray selected blazars of the Fermi LAT Bright AGN Sample (LBAS, Cat. J/ApJ/700/597). By combining our accurately estimated Fermi {gamma}-ray spectra with Swift, radio, infra-red, optical, and other hard X-ray/{gamma}-ray data, collected within 3 months of the LBAS data taking period, we were able to assemble high-quality and quasi-simultaneous spectral energy distributions (SED) for 48 LBAS blazars. We have used these SED to characterize the peak intensity of both the low- and the high-energy components. The results have been used to derive empirical relationships that estimate the position of the two peaks from the broadband colors (i.e., the radio to optical, {alpha}_ro_, and optical to X-ray, {alpha}_ox_, spectral slopes) and from the {gamma}-ray spectral index. While more than 50% of known radio bright high energy peaked (HBL) BL Lacs are detected in the LBAS sample, only less than 13% of known bright broad-lined flat spectrum radio quasars (FSRQs) and LBL BL Lacs are included. This suggests that the latter sources, as a class, may be much fainter {gamma}-ray emitters than LBAS blazars, and could in fact radiate close to the expectations of simple synchrotron self-Compton (SSC) models. We categorized all our sources according to a new physical classification scheme based on the generally accepted paradigm for Active Galactic Nuclei and on the results of this SED study.
854. SED of hard X-ray selected AGN in XMDS
ID:
ivo://CDS.VizieR/J/ApJ/663/81
Title:
SED of hard X-ray selected AGN in XMDS
Short Name:
J/ApJ/663/81
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the SEDs of a hard X-ray selected sample containing 136 sources with F(2-10)keV>10^-14^erg/cm^2^/s; 132 are AGNs. The sources are detected in a 1deg^2^ area of the XMM-Newton Medium Deep Survey where optical data from the VVDS and CFHTLS and infrared data from the SWIRE survey are available. Based on a SED fitting technique we derive photometric redshifts with {sigma}(1+z)=0.11 and 6% of outliers and identify AGN signatures in 83% of the objects. This fraction is higher than derived when a spectroscopic classification is available. The remaining 17% of AGNs show star-forming galaxy SEDs (SF class).
855. 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
856. 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.
857. 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.
858. 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.
859. 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.
860. 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__.