- 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.
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Search Results
- 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/MNRAS/406/197
- Title:
- Ultra-steep spectrum radio sources in SDSS
- Short Name:
- J/MNRAS/406/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse optical and radio properties of radio galaxies detected in the Sloan Digital Sky Survey. The sample of radio sources is selected from the catalogue of Kimball & Ivezic (2008AJ....136..684K) with flux densities at 325, 1400 and 4850MHz, using Westerbork Northern Sky Survey, NRAO VLA Sky Survey and Green Bank 6cm radio surveys and from flux measurements at 74MHz taken from Very Large Array Low-Frequency Sky Survey (Cohen et al. 2006, Cat. VIII/79). We study radio galaxy spectral properties using radio colour-colour diagrams and find that our sample follows a single power law from 74 to 4850MHz.
- ID:
- ivo://CDS.VizieR/J/PASJ/61/177
- Title:
- 15um AKARI observations in CDFS field
- Short Name:
- J/PASJ/61/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep observations of the Chandra Deep Field South have been secured at 15um with AKARI/IRC infrared space telescope. From these observations, we define a sample of mid infrared-selected galaxies at 15um and we also obtain 15um flux densities for a sample of Lyman Break Galaxies at z~1 already observed at 24um with Spitzer/MIPS.
- ID:
- ivo://CDS.VizieR/J/PASP/111/438
- Title:
- Updated Zwicky catalog (UZC)
- Short Name:
- J/PASP/111/438
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Zwicky Catalog of galaxies (ZC), with m_Zw_<=15.5, has been the basis for the Center for Astrophysics (CfA) redshift surveys. To date, analyses of the ZC and redshift surveys based on it have relied on heterogeneous sets of galaxy coordinates and redshifts. Here we correct some of the inadequacies of previous catalogs by providing (1) coordinates with ~<2" errors for all of the 19,369 catalog galaxies, (2) homogeneously estimated redshifts for the majority (98%) of the data taken at the CfA (14,632 spectra), and (3) an estimate of the remaining "blunder" rate for both the CfA redshifts and for those compiled from the literature. For the reanalyzed CfA data we include a calibrated, uniformly determined error and an indication of the presence of emission lines in each spectrum. We provide redshifts for 7257 galaxies in the CfA2 redshift survey not previously published; for another 5625 CfA redshifts we list the remeasured or uniformly rereduced value. Among our new measurements, 1807 are members of UZC "multiplets" associated with the original Zwicky catalog position in the coordinate range where the catalog is 98% complete.
- ID:
- ivo://CDS.VizieR/J/A+AS/123/529
- Title:
- UV-excess quasar candidates around NGC 450
- Short Name:
- J/A+AS/123/529
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the results of a survey for moderately bright quasars performed in a 20.6-square-degree field around the galaxy NGC 450. The quasar candidates we re-selected on the basis of their ultraviolet excess: by comparative visual inspection of the double image of each single object on a U/B dual-exposure Schmidt photographic plate, 95 primary and 45 secondary quasar candidates were selected on the basis of their U image being too bright. The spectroscopic identification of the primary candidates led to the discovery of 59 bona fide quasars (out of which 6 were previously known). The Palomar Schmidt plate was digitised using the MAMA measuring machine and the outcoming data reduced using ad hoc procedures. A photometric calibration allowed us to derive values for the limiting magnitudes and for the U-B index selection threshold of the survey. A catalogue containing 60 quasars is presented with accurate positions, magnitudes and additional information such as redshifts. We studied the spatial distribution of the objects and detected, for the quasars of our sample, a significant deviation from randomness in the form of a propensity to cluster in pairs on the celestial sphere with a typical scale of about 10arcmin. We also formally detected a tendency towards a 3-D clustering, but this result is induced by a single pair of quasars. A forthcoming paper will deal with a similar work performed in a field around NGC 520; the latter field is located directly to the North of the present one and slightly overlaps it.
- ID:
- ivo://CDS.VizieR/J/MNRAS/300/303
- Title:
- UV-selected galaxy redshift survey
- Short Name:
- J/MNRAS/300/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The table contains the first results of a spectroscopic survey of galaxies constructed from a flux-limited sample of stars, galaxies and QSOs imaged at 2000{AA} with the FOCA balloon-borne imaging camera (see Milliard et al., 1992A&A...257...24M) The galaxies were selected in the rest frame ultraviolet (UV), in Selected Area 57. Accurate positions for the UV sources have been obtained by matching with optical counterparts using APM scans of the Palomar Sky Survey limited at B=20.5. The results presented here are derived from optical spectroscopy conducted with the WIYN telescope and the WHT for 142 faint sources. The redshift distribution for this UV- selected sample extends over 0<z<0.5, and a high fraction of the sources show intense nebular emission lines and UV-optical colours bluer than normal Hubble sequence galaxies. Updated results for these galaxies were published later (see Sullivan et al. 2000, Cat. <J/MNRAS/312/442>)
- ID:
- ivo://CDS.VizieR/J/MNRAS/312/442
- Title:
- UV-selected galaxy redshift survey. II.
- Short Name:
- J/MNRAS/312/442
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present further spectroscopic observations for a sample of galaxies selected in the vacuum ultraviolet (UV) at 2000{AA} from the FOCA balloon-borne imaging camera of Milliard et al. (1992A&A...257...24M). This work represents an extension of the initial study by Treyer et al. (Cat. <J/MNRAS/300/303>). Our enlarged catalogue contains 433 sources (~3 times as many as in our earlier study) across two FOCA fields. 273 of these are galaxies, nearly all with redshifts z~0-0.4. Nebular emission-line measurements are available for 216 galaxies, allowing us to address issues of excitation, reddening and metallicity. The UV and H{alpha} luminosity functions strengthen our earlier assertions that the local volume-averaged star formation rate is higher than indicated from earlier surveys. Moreover, internally within our sample, we do not find a steep rise in the UV luminosity density with redshift over 0<z<0.4. Our data are more consistent with a modest evolutionary trend, as suggested by recent redshift survey results. Investigating the emission-line properties, we find no evidence for a significant number of AGN in our sample; most UV-selected sources to z~0.4 are intense star-forming galaxies.
- ID:
- ivo://CDS.VizieR/V/151
- Title:
- VANDELS High-Redshift Galaxy Evolution
- Short Name:
- V/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- VANDELS is a new ESO spectroscopic Public Survey targeting the high-redshift Universe. Exploiting the red sensitivity of the refurbished VIMOS spectrograph, the survey is obtaining ultra-deep optical spectroscopy of around 2100 galaxies in the redshift interval 1.0<z<7.0, with 85% of its targets selected to be at z>=3. The fundamental aim of the survey is to provide the high signal-to-noise spectra necessary to measure key physical properties such as stellar population ages, metallicities and outflow velocities from detailed absorption-line studies. By targeting two extragalactic survey fields with superb multi-wavelength imaging data, VANDELS will produce a unique legacy dataset for exploring the physics underpinning high-redshift galaxy evolution.
- ID:
- ivo://CDS.VizieR/J/MNRAS/268/305
- Title:
- Variability of optically selected quasars
- Short Name:
- J/MNRAS/268/305
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The variability properties of a sample of ~300 optically selected quasars near the South Galactic Pole (SGP) have been studied over a baseline of 16 years using a series of twelve UK Schmidt Telescope B_J_ plates at seven epochs. In this sample there is a correlation between variability and both quasar luminosity and redshift, at greater than the 99 per cent significance level. Quasars of high luminosity show significantly less variability than those with low luminosity, the rms variation ranging from about 0.25mag at M_B_=-23 to 0.1mag at M_B_=-28. The observed trends can be explained by an intrinsic dependence of quasar variability on luminosity combined with the effects of time dilation, and have implications for quasar samples selected by variability or multicolour techniques. The change in the slope of the n(m) relation at the break can be less pronounced in variability-selected samples. Our results can be used to test models for the origin and reprocessing of the continuum emission in quasars.
