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- ID:
- ivo://CDS.VizieR/J/ApJ/643/680
- Title:
- Imaging and spectroscopy around PKS 0405-123
- Short Name:
- J/ApJ/643/680
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a galaxy survey of the field surrounding PKS 0405-123 performed with the WFCCD spectrometer at Las Campanas Observatory. The survey is comprised of two data sets: (1) a greater than 95% complete survey to R=20mag of the field centered on PKS 0405-123 with 10' radius (L~0.1L* and radius of 1Mpc at z=0.1); and (2) a set of four discontiguous (i.e., non-overlapping), flanking fields covering ~1deg^2^ area with completeness ~90% to R=19.5mag. With these data sets, one can examine the local and large-scale galactic environment of the absorption systems identified toward PKS 0405-123. In this paper, we focus on the O VI systems analyzed in Paper I (Prochaska et al., 2004, Cat. <J/ApJ/617/718>). The results suggest that this gas arises in a diverse set of galactic environments including the halos of individual galaxies, galaxy groups, filamentary-like structures, and also regions devoid of luminous galaxies. In this small sample, there are no obvious trends between galactic environment and the physical properties of the gas. Furthermore, we find similar results for a set of absorption systems with comparable NHI but no detectable metal lines. The observations indicate that metals are distributed throughout a wide range of environments in the local universe. Future papers in this series will address the distribution of galactic environments associated with metal-line systems and the Ly forest based on data for over 10 additional fields. All of the spectra and fits tables are available at http://www.ucolick.org/~xavier/WFCCDOVI/
- ID:
- ivo://CDS.VizieR/J/MNRAS/405/2302
- Title:
- Improved redshifts for SDSS quasar spectra
- Short Name:
- J/MNRAS/405/2302
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A systematic investigation of the relationship between different redshift estimation schemes for more than 91000 quasars in the Sloan Digital Sky Survey (SDSS) Data Release 6 is presented. The publicly available SDSS quasar redshifts are shown to possess systematic biases of {Delta}z/(1+z)>=0.002 (600km/s) over both small ({delta}z~=0.1) and large ({delta}z~=1) redshift intervals. Empirical relationships between redshifts based on (i) CaII H&K host galaxy absorption, (ii) quasar [OII] {lambda}{lambda}3728, (iii) [OIII] {lambda}{lambda} 4960, 5008 emission and (iv) cross-correlation (with a master-quasar template) that includes, at increasing quasar redshift, the prominent MgII {lambda}{lambda} 2799, CIII] {lambda}{lambda} 1908 and CIV {lambda}{lambda} 1549 emission lines are established as a function of quasar redshift and luminosity. New redshifts in the resulting catalogue possess systematic biases, a factor of ~=20 lower compared to the SDSS redshift values; systematic effects are reduced to the level of {Delta}z/(1+z) (30km/s) per unit redshift or <=2.5x10^-5^ per unit absolute magnitude. Redshift errors, including components due both to internal reproducibility and to the intrinsic quasar-to-quasar variation among the population, are available for all quasars in the catalogue. The improved redshifts and their associated errors have wide applicability in areas such as quasar absorption outflows, quasar clustering, quasar-galaxy clustering and proximity-effect determinations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/499/6053
- Title:
- Indiv. opt. variability of AGNs from MEXSAS2
- Short Name:
- J/MNRAS/499/6053
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- At present, most of the variability studies of active galactic nuclei (AGNs) are based on ensemble analyses. Nevertheless, it is interesting to provide estimates of the individual variability properties of each AGN, in order to relate them with intrinsic physical quantities. A useful dataset is provided by the Catalina Surveys Data Release 2 (CSDR2), which encompasses almost a decade of photometric measurements of ~500 million objects repeatedly observed hundreds of times.We aim to investigate the individual optical variability properties of 795 AGNs originally included in the Multi-Epoch XMMSerendipitous AGN Sample 2 (MEXSAS2). Our goals consist in: (i) searching for correlations between variability and AGN physical quantities; (ii) extending our knowledge of the variability features of MEXSAS2 from the X-ray to the optical.We use the structure function (SF) to analyse AGN flux variations. We model the SF as a power-law, SF(tau)=A(tau/tau_0)^gamma^, and we compute its variability parameters. We introduce the V-correction as a simple tool to correctly quantify the amount of variability in the rest frame of each source.We find a significant decrease of variability amplitude with increasing bolometric, optical and X-ray luminosity. We obtain the indication of an intrinsically weak positive correlation between variability amplitude and redshift, z. Variability amplitude also appears to be positively correlated with alpha_{ox}.The slope of the power-law SF, gamma, is weakly correlated with the bolometric luminosity L_{bol} and/or with the black hole mass M_{BH}. When comparing optical to X-ray variability properties, we find that X-ray variability amplitude is approximately the same for those AGNs with larger or smaller variability amplitude in the optical.On the contrary, AGNs with steeper SF in the optical do present steeper SF in the X-ray, and vice versa.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/1105
- Title:
- Intermediate high-velocity clouds distances
- Short Name:
- J/MNRAS/415/1105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectra of 403 stars and quasi-stellar objects in order to obtain distance limits towards intermediate- and high-velocity clouds (IHVCs), including new Fibre-fed Extended Range Optical Spectrograph (FEROS) observations plus archival ELODIE, FEROS, High Resolution Echelle Spectrometer (HIRES) and Ultraviolet and Visual Echelle Spectrograph (UVES) data.
- 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.
