- ID:
- ivo://CDS.VizieR/J/ApJ/824/130
- Title:
- SDSS/BOSS/TDSS CIV BAL quasars
- Short Name:
- J/ApJ/824/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the largest systematic investigation of broad absorption line (BAL) acceleration to date. We use spectra of 140 quasars from three Sloan Digital Sky Survey programs to search for global velocity offsets in BALs over timescales of ~2.5-5.5 years in the quasar rest frame. We carefully select acceleration candidates by requiring monolithic velocity shifts over the entire BAL trough, avoiding BALs with velocity shifts that might be caused by profile variability. The CIV BALs of two quasars show velocity shifts consistent with the expected signatures of BAL acceleration, and the BAL of one quasar shows a velocity-shift signature of deceleration. In our two acceleration candidates, we see evidence that the magnitude of the acceleration is not constant over time; the magnitudes of the change in acceleration for both acceleration candidates are difficult to produce with a standard disk-wind model or via geometric projection effects. We measure upper limits to acceleration and deceleration for 76 additional BAL troughs and find that the majority of BALs are stable to within about 3% of their mean velocities. The lack of widespread acceleration/deceleration could indicate that the gas producing most BALs is located at large radii from the central black hole and/or is not currently strongly interacting with ambient material within the host galaxy along our line of sight.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/210/3
- Title:
- SDSS bulge, disk and total stellar mass estimates
- Short Name:
- J/ApJS/210/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of bulge, disk, and total stellar mass estimates for ~660000 galaxies in the Legacy area of the Sloan Digital Sky Survey Data (SDSS) Release 7. These masses are based on a homogeneous catalog of g- and r-band photometry described by Simard et al. (2011, Cat. J/ApJS/196/11), which we extend here with bulge+disk and Sersic profile photometric decompositions in the SDSS u, i, and z bands. We discuss the methodology used to derive stellar masses from these data via fitting to broadband spectral energy distributions (SEDs), and show that the typical statistical uncertainty on total, bulge, and disk stellar mass is ~0.15 dex. Despite relatively small formal uncertainties, we argue that SED modeling assumptions, including the choice of synthesis model, extinction law, initial mass function, and details of stellar evolution likely contribute an additional 60% systematic uncertainty in any mass estimate based on broadband SED fitting. We discuss several approaches for identifying genuine bulge+disk systems based on both their statistical likelihood and an analysis of their one-dimensional surface-brightness profiles, and include these metrics in the catalogs. Estimates of the total, bulge and disk stellar masses for both normal and dust-free models and their uncertainties are made publicly available here.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1002
- Title:
- SDSS candidate type II quasars. II
- Short Name:
- J/AJ/128/1002
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Type II quasars are luminous active galactic nuclei (AGNs) whose central engines and broad-line regions are obscured by intervening material; such objects only recently have been discovered in appreciable numbers. We study the multiwavelength properties of 291 type II AGN candidates (0.3<z<0.8) selected on the basis of their optical emission-line properties from the spectroscopic database of the Sloan Digital Sky Survey (Cat. <J/AJ/126/2579>). This sample includes about 150 objects luminous enough to be classified as type II quasars. We matched the sample to the FIRST (20cm, Cat.<VIII/71>), IRAS (12-100{mu}m, Cat. <II/125>), 2MASS (JHK_s_, Cat. <II/246>), and RASS (0.1-2.4keV, Cat. <IX/29>) surveys. Roughly 10% of optically selected type II AGN candidates are radio-loud, comparable to the AGN population as a whole. About 40 objects are detected by IRAS at 60 and/or 100{mu}m, and the inferred mid/far-IR luminosities lie in the range L=10^45^-3x10^46^ergs/s. Average IR-to-[OIII]{lambda}5007 ratios of objects in our sample are consistent with those of other AGNs. Objects from our sample are 10 times less likely to have soft X-ray counterparts in RASS than type I AGNs with the same redshifts and [OIII]{lambda}5007 luminosities. The few type II AGN candidates from our sample that are detected by RASS have harder X-ray spectra than those of type I AGNs. The multiwavelength properties of the type II AGN candidates from our sample are consistent with their interpretation as powerful obscured AGNs.
1174. SDSS-C4 cluster catalog
- ID:
- ivo://CDS.VizieR/J/AJ/130/968
- Title:
- SDSS-C4 cluster catalog
- Short Name:
- J/AJ/130/968
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the C4 Cluster Catalog, a new sample of 748 clusters of galaxies identified in the spectroscopic sample of the Second Data Release (DR2, 2004AJ....128..502A) of the Sloan Digital Sky Survey (SDSS). The C4 cluster-finding algorithm identifies clusters as overdensities in a seven-dimensional position and color space, thus minimizing projection effects that have plagued previous optical cluster selection. The present C4 catalog covers ~2600deg^2^ of sky and ranges in redshift from z=0.02 to 0.17. The mean cluster membership is 36 galaxies (with measured redshifts) brighter than r=17.7, but the catalog includes a range of systems, from groups containing 10 members to massive clusters with over 200 cluster members with measured redshifts. The catalog provides a large number of measured cluster properties including sky location, mean redshift, galaxy membership, summed r-band optical luminosity (L_r_), and velocity dispersion, as well as quantitative measures of substructure and the surrounding large-scale environment. We use new, multicolor mock SDSS galaxy catalogs, empirically constructed from the {Lambda}CDM Hubble Volume (HV) Sky Survey output, to investigate the sensitivity of the C4 catalog to the various algorithm parameters (detection threshold, choice of passbands, and search aperture), as well as to quantify the purity and completeness of the C4 cluster catalog.
1175. SDSS DR2 BAL QSOs
- ID:
- ivo://CDS.VizieR/J/ApJ/665/990
- Title:
- SDSS DR2 BAL QSOs
- Short Name:
- J/ApJ/665/990
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have investigated a sample of 5088 quasars from the SDSS DR2 in order to determine how the frequency and properties of BALs depend on black hole mass, bolometric luminosity, Eddington fraction (L/L_Edd_), and spectral slope. We focus only on high-ionization BALs and find a number of significant results. While quasars accreting near the Eddington limit are more likely to show BALs than lower L/LEdd systems, BALs are present in quasars accreting at only a few percent Eddington. We find a stronger effect with bolometric luminosity, such that the most luminous quasars are more likely to show BALs. There is an additional effect, previously known, that BAL quasars are redder on average than unabsorbed quasars. The strongest effects involving the quasar physical properties and BAL properties are related to terminal outflow velocity. Maximum observed outflow velocities increase with both the bolometric luminosity and the blueness of the spectral slope, suggesting that the ultraviolet luminosity to a great extent determines the acceleration. These results support the idea of outflow acceleration via ultraviolet line scattering.
1176. SDSS-DR7 broad-line QSOs
- ID:
- ivo://CDS.VizieR/J/ApJ/804/L15
- Title:
- SDSS-DR7 broad-line QSOs
- Short Name:
- J/ApJ/804/L15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical FeII strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/L_Edd_) of the black hole (BH) accretion. Shen & Ho (2014Natur.513..210S) demonstrated with quasar clustering analysis that the average BH mass decreases with increasing FeII strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion {sigma}_*_ (hence, the BH mass via the M-{sigma}_*_ relation) from decomposed host spectra in low-redshift Sloan Digital Sky Survey quasars. We found that at fixed quasar luminosity, {sigma}_*_ systematically decreases with increasing FeII strength, confirming that the Eddington ratio increases with FeII strength. We also found that at fixed luminosity and FeII strength, there is little dependence of {sigma}_*_ on the broad H{beta} FWHM. These new results reinforce the framework that the Eddington ratio and orientation govern most of the diversity seen in broad-line quasar properties.
- ID:
- ivo://CDS.VizieR/J/ApJS/223/20
- Title:
- SDSS-DR8 galaxies classified by WND-CHARM
- Short Name:
- J/ApJS/223/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have applied computer analysis to classify the broad morphological types of ~3x10^6^ Sloan Digital Sky Survey (SDSS) galaxies. For each galaxy, the catalog provides the DR8 object ID, the R.A., the decl., and the certainty for the automatic classification as either spiral or elliptical. The certainty of the classification allows us to control the accuracy of a subset of galaxies by sacrificing some of the least certain classifications. The accuracy of the catalog was tested using galaxies that were classified by the manually annotated Galaxy Zoo catalog. The results show that the catalog contains ~900000 spiral galaxies and ~600000 elliptical galaxies with classification certainty that has a statistical agreement rate of ~98% with the Galaxy Zoo debiased "superclean" data set. The catalog also shows that objects assigned by the SDSS pipeline with a relatively high redshift (z>0.4) can have clear visual spiral morphology.
- ID:
- ivo://CDS.VizieR/J/AJ/142/122
- Title:
- SDSS DR7 galaxy/QSOs pairs
- Short Name:
- J/AJ/142/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this project is to identify low-redshift host galaxies of quasar absorption-line systems by selecting galaxies that are seen in projection onto quasar sightlines. To this end, we use the Seventh Data Release of the Sloan Digital Sky Survey to construct a parent sample of 97489 galaxy/quasar projections at impact parameters of up to 100 kpc to the foreground galaxy. We then search the quasar spectra for absorption-line systems of CaII and NaI within +/-500km/s1 of the galaxy's velocity. This yields 92 CaII and 16 NaI absorption systems.
- ID:
- ivo://CDS.VizieR/J/ApJS/220/3
- Title:
- SDSS-DR7 isolated galaxy morphologies
- Short Name:
- J/ApJS/220/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Isolated galaxies in low-density regions are significant in the sense that they are least affected by the hierarchical pattern of galaxy growth and interactions with perturbers, at least for the last few gigayears. To form a comprehensive picture of the star-formation history of isolated galaxies, we constructed a catalog of isolated galaxies and their comparison sample in relatively denser environments. The galaxies are drawn from the Sloan Digital Sky Survey Data Release 7 in the redshift range of 0.025<z<0.044. We performed a visual inspection and classified their morphology following the Hubble classification scheme. For the spectroscopic study, we make use of the catalog provided by Oh et al. (2011ApJS..195...13O). We confirm most of the earlier understanding on isolated galaxies. The most remarkable additional results are as follows. Isolated galaxies are dominantly late type with the morphology distribution (E:S0:S:Irr)=(9.9:11.3:77.6:1.2)%. The frequency of elliptical galaxies among isolated galaxies is only a third of that of the comparison sample. Most of the photometric and spectroscopic properties are surprisingly similar between the isolated and comparison samples. However, early-type isolated galaxies are less massive by 50% and younger (by H{beta}) by 20% than their counterparts in the comparison sample. This can be explained as a result of different merger and star-formation histories for differing environments in the hierarchical merger paradigm.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/62
- Title:
- SDSS-DR7 optical spectra analysis of radio galaxies
- Short Name:
- J/ApJ/765/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study a large sample of narrow-line radio galaxies (NLRGs) with extended radio structures. Using 1.4GHz radio luminosities L_1.4_, narrow optical emission line luminosities L_[OIII]_ and L_Halpha_, as well as black hole masses M_BH_ derived from stellar velocity dispersions measured from the optical spectra obtained with the Sloan Digital Sky Survey, we find that (1) NLRGs cover about four decades of the Eddington ratio, {lambda}{equiv}L_bol_/L_Edd_{prop.to}L_line_/M_BH_; (2) L_1.4_/M_BH_ strongly correlates with {lambda}; and (3) radio loudness, R=L_1.4_/L_Line_, strongly anti-correlates with {lambda}. A very broad range of the Eddington ratio indicates that the parent population of NLRGs includes both radio-loud quasars (RLQs) and broad-line radio galaxies (BLRGs). The correlations they obey and their high jet production efficiencies favor a jet production model which involves the so-called magnetically choked accretion scenario. In this model, production of the jet is dominated by the Blandford-Znajek mechanism, and the magnetic fields in the vicinity of the central black hole are confined by the ram pressure of the accretion flow. Since large net magnetic flux accumulated in central regions of the accretion flow required by the model can take place only via geometrically thick accretion, we speculate that the massive, "cold" accretion events associated with luminous emission-line active galactic nucleus can be accompanied by an efficient jet production only if preceded by a hot, very sub-Eddington accretion phase.
