- ID:
- ivo://CDS.VizieR/J/AJ/128/544
- Title:
- UBRI Photometry of Quasars
- Short Name:
- J/AJ/128/544
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBRI photometry and spectra for 60 quasars found within 1{deg}^2^ centered on the J0053+1234 region, which has been the subject of the Caltech Faint Galaxy Redshift Survey. Candidate quasars were selected by their ultraviolet excess with respect to the stellar locus and confirmed spectroscopically. The quasars span a wide range in brightness (17.5<B<21.6) and redshift (0.43<z<2.38).
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/140/351
- Title:
- UBV photometry of SGP AGNs
- Short Name:
- J/A+AS/140/351
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectra, position, magnitudes and colors are presented for 485 faint (B_J_<20.5) emission line objects selected with the ultraviolet-excess (UVX) criterion on a area of 24.6 sq. deg. in the South Galactic Pole. The objects were selected from the analysis of pixel-to-pixel stacking of COSMOS scans of UKST U_J_ and R plates. The candidates were observed with the Meudon-ESO Fiber Optics System (MEFOS) at the ESO 3.6m telescope. 429 type 1 AGNs have been identified (373 in the redshift range 0.3<z<=2.2). This sample has allowed the measure of a difference on the QSO clustering evolution in comparison with that found for galaxies (La Franca et al., 1998ApJ...497..529L). The region is part of the ESO Imaging Survey (EIS) and of the 2dF QSO redshift survey.
- ID:
- ivo://CDS.VizieR/J/AJ/119/2571
- Title:
- UBVRI photometry of HDF QSOs and galaxies
- Short Name:
- J/AJ/119/2571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have imaged a 45'x45' area centered on the Hubble Deep Field (HDF) in UBVRI passbands, down to the limiting magnitudes of approximately 21.5, 22.5, 22.2, 22.2, and 21.2, respectively. The principal goals of the survey are to identify quasi-stellar objects (QSOs) and to map structure traced by luminous galaxies and QSO absorption line systems in a wide volume containing the HDF. The area surveyed is 400 times as large as that of the HDF, and 40 times as large as that of the HDF Flanking Fields. We have selected QSO candidates from color space and identified four QSOs and two narrow emission line galaxies not yet discovered, bringing the total number of known QSOs in the area to 19.
- ID:
- ivo://CDS.VizieR/J/ApJS/171/29
- Title:
- UCSD/Keck Damped Ly{alpha} Abundance Database
- Short Name:
- J/ApJS/171/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We publish the Keck/HIRES and Keck/ESI spectra that we have obtained during the first 10 years of Keck observatory operations. Our full sample includes 42 HIRES spectra and 39 ESI spectra along 65 unique sight lines providing abundance measurements on about 85 DLA systems. The normalized data can be downloaded from the journal or from our supporting Web site. The database includes all of the sight lines that have been included in our papers on the chemical abundances, kinematics, and metallicities of the damped Ly{alpha} systems. This data has also been used to argue for variations in the fine-structure constant. We present new chemical abundance measurements for 10 damped Ly{alpha} systems and a summary table of high-resolution metallicity measurements (including values from the literature) for 153 damped Ly{alpha} systems at z>1.6. We caution, however, that this metallicity sample (and all previous ones) is biased to higher N_HI_ values than a random sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/123/377
- Title:
- u*g*r*i*z* Photometry of stars, galaxies, QSOs
- Short Name:
- J/ApJS/123/377
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog (table 5 of the paper) contains the measurements of 2262 sources, including 334 extended sources, 1915 point sources, and 13 known QSOs, in five passbands close to the u'g'r'i'z' passbands of SDSS (see the definition of the photometric system in Richards et al., 1997PASP..109...39R). Of these objects, over 1600 are measured in 15 fields covering 0.5deg^2^, with a limiting magnitude of r*<19.5, similar to the photometric limit of the SDSS spectroscopic survey.
- ID:
- ivo://CDS.VizieR/J/MNRAS/341/993
- Title:
- u_j_br photometry and redshifts of QSOs
- Short Name:
- J/MNRAS/341/993
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed analysis of a sample of radio-detected quasars, obtained by matching together objects from the FIRST (<VIII/71>) survey and the 2dF Quasar Redshift Survey (2dF, <VII/223>). The data set consists of 113 sources, spanning a redshift range 0.35<~z<~2.2, with optical magnitudes 18.25<=bj<=20.85 and radio fluxes S_1.4GHz_>=1mJy. These objects exhibit properties such as redshift and colour distribution in full agreement with those derived for the whole quasar population, suggesting that the mechanism(s) controlling the birth and lifetime of quasars are independent of their level of radio emission. The long-debated question of the radio-loud/radio quiet (RL/RQ) dichotomy is then investigated for the combined FIRST-2dF and FIRST-LBQS (Large Bright Quasar Survey) samples, as they present similar selection criteria.
- ID:
- ivo://CDS.VizieR/J/ApJ/778/127
- Title:
- UKIDSS+FIRST+SDSS red QSOs candidates
- Short Name:
- J/ApJ/778/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a pilot survey to find dust-reddened quasars by matching the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio catalog to the UKIDSS near-infrared survey and using optical data from Sloan Digital Sky Survey to select objects with very red colors. The deep K-band limit provided by UKIDSS allows for finding more heavily reddened quasars at higher redshifts as compared with previous work using FIRST and Two Micron All Sky Survey (2MASS). We selected 87 candidates with K<=17.0 from the UKIDSS Large Area Survey (LAS) First Data Release (DR1), which covers 190deg^2^. These candidates reach up to ~1.5mag below the 2MASS limit and obey the color criteria developed to identify dust-reddened quasars. We have obtained 61 spectroscopic observations in the optical and/or near-infrared, as well as classifications in the literature, and have identified 14 reddened quasars with E(B-V)>0.1, including 3 at z>2. We study the infrared properties of the sample using photometry from the Wide-Field Infrared Survey Explorer and find that infrared colors improve the efficiency of red quasar selection, removing many contaminants in an infrared-to-optical color-selected sample alone. The highest-redshift quasars (z>~2) are only moderately reddened, with E(B-V)~0.2-0.3. We find that the surface density of red quasars rises sharply with faintness, comprising up to 17% of blue quasars at the same apparent K-band flux limit. We estimate that to reach more heavily reddened quasars (i.e., E(B-V)>~0.5) at z>2 and a depth of K=17, we would need to survey at least ~2.5 times more area.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A92
- Title:
- Ultracompact extragalactic radio sources at 86GHz
- Short Name:
- J/A+A/622/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Very long baseline interferometry (VLBI) observations at 86 GHz (wavelength, {lambda}=3mm) reach a resolution of about 50{mu}as, probing the collimation and acceleration regions of relativistic outflows in active galactic nuclei (AGN). The physical conditions in these regions can be studied by performing 86GHz VLBI surveys of representative samples of compact extragalactic radio sources. To extend the statistical studies of compact extragalactic jets, a large global 86GHz VLBI survey of 162 compact radio sources was conducted in 2010-2011 using the Global Millimeter VLBI Array (GMVA). The survey observations were made in a snapshot mode, with up to five scans per target spread over a range of hour angles in order to optimize the visibility coverage. The survey data attained a typical baseline sensitivity of 0.1Jy and a typical image sensitivity of 5mJy/beam, providing successful detections and images for all of the survey targets. For 138 objects, the survey provides the first ever VLBI images made at 86GHz. Gaussian model fitting of the visibility data was applied to represent the structure of the observed sources and to estimate the flux densities and sizes of distinct emitting regions (components) in their jets. These estimates were used for calculating the brightness temperature (Tb) at the jet base (core) and in one or more moving regions (jet components) downstream from the core. These model-fit-based estimates of Tb were compared to the estimates of brightness temperature limits made directly from the visibility data, demonstrating a good agreement between the two methods. The apparent brightness temperature estimates for the jet cores in our sample range from 2.5x10^9^K to 1.3x10^12^K, with the mean value of 1.8x10^11^K. The apparent brightness temperature estimates for the inner jet components in our sample range from 7.0x10^7^K to 4.0x10^11^K. A simple population model with a single intrinsic value of brightness temperature, T0, is applied to reproduce the observed distribution. It yields T0=(3.77^+0.10^_0.14_)10^11^K for the jet cores, implying that the inverse Compton losses dominate the emission. In the nearest jet components, T0=(1.42^+0.16^_0.19_)10^11^K is found, which is slightly higher than the equipartition limit of 5x10^10^K expected for these jet regions. For objects with sufficient structural detail detected, the adiabatic energy losses are shown to dominate the observed changes of brightness temperature along the jet.
- ID:
- ivo://CDS.VizieR/J/AJ/137/3761
- Title:
- Ultraviolet quasi-stellar objects
- Short Name:
- J/AJ/137/3761
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of spectroscopically confirmed quasi-stellar objects (QSOs) with FUV-NUV color (as measured by Galaxy Evolution Explorer (GALEX) photometry, FUV band: 1344-1786{AA}, NUV band: 1771-2831{AA}) bluer than canonical QSO templates and than the majority of known QSOs. We analyze their FUV to NIR colors, luminosities, and optical spectra. The sample includes a group of 150 objects at low redshift (z<0.5), and a group of 21 objects with redshift 1.7<z<2.6.
- ID:
- ivo://CDS.VizieR/J/AJ/127/646
- Title:
- Unbiased census of AGN in 2MASS
- Short Name:
- J/AJ/127/646
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an unbiased near-IR-selected AGN sample, covering 12.56deg^2^ down to Ks~15.5, selected from the Two Micron All Sky Survey (2MASS). Our only selection effect is a moderate color cut (J-Ks>1.2) designed to reduce contamination from Galactic stars. We observed both pointlike and extended sources.
