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- ID:
- ivo://CDS.VizieR/J/ApJ/683/L115
- Title:
- Intermediate-line region in quasars
- Short Name:
- J/ApJ/683/L115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a systematic investigation of the H{beta} and FeII emission lines in a sample of 568 quasars within z<0.8 selected from the Sloan Digital Sky Survey quasar catalog (DR5, Cat. VII/252). The conventional broad H{beta} emission line can be decomposed into two components: one with intermediate velocity width and another with very broad width. The velocity shift and equivalent width of the intermediate-width component do not correlate with those of the very broad component of H{beta}, but its velocity shift and width do resemble FeII. Moreover, the width of the very broad component is roughly 2.5 times that of the intermediate-width component. These characteristics strongly suggest the existence of an intermediate-line region, whose kinematics seem to be dominated by infall, located at the outer portion of the broad-line region.
- ID:
- ivo://CDS.VizieR/J/AJ/162/121
- Title:
- 3627 International Celestial Reference Frame sources
- Short Name:
- J/AJ/162/121
- Date:
- 16 Mar 2022 00:11:36
- Publisher:
- CDS
- Description:
- The third iteration of the International Celestial Reference Frame (ICRF3) is made up of 4536 quasars observed at S/X bands using very-long-baseline interferometry. These sources are high-redshift quasars, typically between 1<z<2, that are believed to host active galactic nuclei at their centers. The position of compact radio sources can be determined better than sources with large amounts of extended radio structure. Here we report information on a series of 20 observations from 2017 January through December 2017 that were designed for precise astrometry and to monitor the structure of sources included in the ICRF3. We targeted 3627 sources over the one year campaign and found the median flux density of 2697 detected sources at S band is 0.13Jy, and the median flux density of 3209 sources detected at X band is 0.09Jy. We find that 70% of detected sources in our campaign are considered compact at X band and ideal for use in the ICRF and 89% of the 2615 sources detected at both frequencies have a flat spectral index, {alpha}>0.5
- ID:
- ivo://CDS.VizieR/J/A+A/403/555
- Title:
- Interplanetary Scintillation Pushchino Survey
- Short Name:
- J/A+A/403/555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interplanetary scintillating (IPS) radio sources from the Pushchino Survey (PS) in the area of 0.11sr have been cross-identified with objects from the 7C and FIRST catalogues. We have obtained improved positions of IPS radio sources, which are necessary for their optical identification. The data on sizes and morphology provided by the FIRST catalogue have shown that more than 50% of IPS radio sources are single and compact (<3") at {nu}=1400MHz. Most of them belong to the class of compact steep spectrum radio sources. About 15% of IPS radio sources are single partially resolved FIRST objects (sizes of 3"-9") and another 11% are double radio sources with compact components. The remaining 22% have larger sizes and, as a rule, a more complex structure too. Because IPS sources certainly contain an appreciable part of their radiation at low frequencies (100MHz) in very compact (~0.1") components and have steep spectra, we hope that a significant part of the Pushchino Survey objects are very probable candidates for steep spectrum quasars.
- ID:
- ivo://CDS.VizieR/J/A+A/421/455
- Title:
- Interplanetary Scintillation Pushchino Survey II
- Short Name:
- J/A+A/421/455
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of optical identification of 248 interplanetary scintillating (IPS) radio sources from the Pushchino Survey (PS) in the area of 0.11sr with the center at RA=10h28m, DE=+41{deg}. All 260 counterparts of IPS radio sources from the 7C and FIRST catalogues, which had been found in Paper I (Cat. <J/A+A/403/555>), were considered. We used USNO-B1.0 catalogue (limiting magnitude m_R_~21) for the optical identification and searched the literature to find optical data for fainter objects. Photometric and spectroscopic observations were conducted on the 1m and 6m telescopes of SAO RAS. Optical magnitudes or deep limits for 22 objects and redshifts for 26 ones have been obtained. In total, we collected optical data for 116 (68 with redshift) counterparts of the PS radio sources. For the subsample of the PS quasars (41 objects) the redshift distribution was compared to those of several other samples of quasars (BRL, 3CRR, MQS, B3-VLA, 7CRS I-III and PKS 0.25Jy) which have complete or nearly complete redshift information.
- ID:
- ivo://CDS.VizieR/J/MNRAS/471/59
- Title:
- Intrinsic AGN SEDs in PG quasars
- Short Name:
- J/MNRAS/471/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new analysis of the Palomar-Green quasar sample based on Spitzer and Herschel observations. (i) Assuming polycyclic aromatic hydrocarbon (PAH)-based star formation luminosities (L_SF_) similar to Symeonidis et al. (S16, 2016MNRAS.459..257S), we find mean and median intrinsic active galactic nucleus (AGN) spectral energy distributions (SEDs). These, in the far-infrared (FIR), appear hotter and significantly less luminous than the S16 mean intrinsic AGN SED. The differences are mostly due to our normalization of the individual SED that properly accounts for a small number of very FIR-luminous quasars. Our median, PAH-based SED represents ~6 per cent increase on the 1-243{mu}m luminosity of the extended Mor & Netzer (EM12, 2012MNRAS.420..526M) torus SED, while S16 find a significantly larger difference. It requires large-scale dust with T~20-30K, which, if optically thin and heated by the AGN, would be outside the host galaxy. (ii) We also explore the black hole and stellar mass growths, using L_SF_ estimates from fitting Herschel/PACS observations after subtracting the EM12 torus contribution. We use rough estimates of stellar mass, based on scaling relations, to divide our sample into groups: on, below and above the star formation main sequence (SFMS). Objects on the SFMS show a strong correlation between star formation luminosity and AGN bolometric luminosity, with a logarithmic slope of ~0.7. Finally, we derive the relative duty cycles of this and another sample of very luminous AGN at z=2-3.5. Large differences in this quantity indicate different evolutionary pathways for these two populations characterized by significantly different black hole masses.
- ID:
- ivo://CDS.VizieR/J/ApJ/841/76
- Title:
- Intrinsic far-IR SED of luminous AGNs
- Short Name:
- J/ApJ/841/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The range of currently proposed active galactic nucleus (AGN) far-infrared templates results in uncertainties in retrieving host galaxy information from infrared observations and also undermines constraints on the outer part of the AGN torus. We discuss how to test and reconcile these templates. Physically, the fraction of the intrinsic AGN IR-processed luminosity compared with that from the central engine should be consistent with the dust-covering factor. In addition, besides reproducing the composite spectral energy distributions (SEDs) of quasars, a correct AGN IR template combined with an accurate library of star-forming galaxy templates should be able to reproduce the IR properties of the host galaxies, such as the luminosity-dependent SED shapes and aromatic feature strengths. We develop tests based on these expected behaviors and find that the shape of the AGN intrinsic far-IR emission drops off rapidly starting at ~20{mu}m and can be matched by an Elvis+ (1994, J/ApJS/95/1)-like template with a minor modification. Despite the variations in the near- to mid-IR bands, AGNs in quasars and Seyfert galaxies have remarkably similar intrinsic far-IR SEDs at {lambda}~20-100{mu}m, suggesting a similar emission character of the outermost region of the circumnuclear torus. The variations of the intrinsic AGN IR SEDs among the type-1 quasar population can be explained by the changing relative strengths of four major dust components with similar characteristic temperatures, and there is evidence for compact AGN-heated dusty structures at sub-kiloparsec scales in the far-IR.
- ID:
- ivo://CDS.VizieR/J/A+A/376/28
- Title:
- Inversion of the HE 1122-1648 UVES spectrum
- Short Name:
- J/A+A/376/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File tablea1.dat contains the list of the Lyman-{alpha} absorption lines identified in the spectrum of HE 1122-1648 obtained during Science Verification of UVES at the VLT. We used the standard method of Voigt Profile fitting with VPFIT and with the inversion method described in the related paper. (Note that the printed version of the paper indicates HE 1122-1628, instead of the quasar HE 1122-1648).
- ID:
- ivo://CDS.VizieR/J/ApJS/168/213
- Title:
- Ionization states and cooling efficiencies
- Short Name:
- J/ApJS/168/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new computations of the equilibrium and nonequilibrium cooling efficiencies and ionization states for low-density radiatively cooling gas containing the elements H, He, C, N, O, Ne, Mg, Si, S, and Fe. We present results for gas temperatures between 10^4^ and 10^8^K, assuming dust-free and optically thin conditions, and no external radiation.
- ID:
- ivo://CDS.VizieR/J/AJ/159/216
- Title:
- Ions density in the CGM of low mass galaxy groups
- Short Name:
- J/AJ/159/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore how environment affects the metallicity of the circumgalactic medium (CGM) using 13 low-mass galaxy groups (two to five galaxies) at <z_abs_>=0.25 identified near background quasars. Using quasar spectra from the Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) and from Keck/High Resolution Echelle Spectrometer (Keck/HIRES) or the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph (VLT/UVES), we measure column densities of or determine limits on CGM absorption lines. We use a Markov Chain Monte Carlo approach with Cloudy to estimate metallicities of cool (T~104K) CGM gas within groups and compare them to CGM metallicities of 47 isolated galaxies. Both group and isolated CGM metallicities span a wide range (-2<[Si/H]<0), where the mean group (-0.54{pm}0.22) and isolated (-0.77{pm}0.14) CGM metallicities are similar. Group and isolated environments have similar distributions of HI column densities as a function of impact parameter. However, contrary to isolated galaxies, we do not find an anticorrelation between HI column density and the nearest group galaxy impact parameter. We additionally divided the groups by member luminosity ratios (i.e., galaxy-galaxy and galaxy-dwarf groups). While there was no significant difference in their mean metallicities, a modest increase in sample size should allow one to statistically identify a higher CGM metallicity in galaxy-dwarf groups compared to galaxy-galaxy groups. We conclude that either environmental effects have not played an important role in the metallicity of the CGM at this stage and expect that this may only occur when galaxies are strongly interacting or merging or that some isolated galaxies have higher CGM metallicities due to past interactions. Thus, environment does not seem to be the cause of the CGM metallicity bimodality.
