- ID:
- ivo://CDS.VizieR/J/A+A/637/A52
- Title:
- Deep Chandra survey in J1030+0524 field
- Short Name:
- J/A+A/637/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the X-ray source catalog for the 479ks Chandra exposure of the SDSS J1030+0524 field, that is centered on a region that shows the best evidence to date of an overdensity around a z>6 quasar, and also includes a galaxy overdensity around a Comptonthick Fanaro-Riley type II (FRII) radio galaxy at z=1.7. Using wavdetect for initial source detection and ACIS Extract for source photometry and significance assessment, we create preliminary catalogs of sources that are detected in the full (0.5-7.0keV), soft (0.5-2.0keV), and hard (2-7keV) bands, respectively. We produce X-ray simulations that mirror our Chandra observation to filter our preliminary catalogs and get a completeness level of > 91% and a reliability level of 95% in each band. The catalogs in the three bands are then matched into a final main catalog of 256 unique sources. Among them, 244, 193, and 208 are detected in the full, soft, and hard bands, respectively. The Chandra observation covers a total area of 335 arcmin2, and reaches flux limits over the central few square arcmins of ~3x10^-16^, 6x10^-17^, and 2x10^-16^erg/cm2/s in the full, soft, and hard bands, respectively This makes J1030 field the fifth deepest extragalactic X-ray survey to date. The field is part of the Multiwavelength Survey by Yale-Chile (MUSYC), and is also covered by optical imaging data from the Large Binocular Camera (LBC) at the Large Binocular Telescope (LBT), near-IR imaging data from the Canada France Hawaii Telescope WIRCam (CFHT/WIRCam), and Spitzer IRAC. Thanks to its dense multi-wavelength coverage, J1030 represents a legacy field for the study of large-scale structures around distant accreting supermassive black holes. Using a likelihood ratio analysis, we associate multi-band (r, z, J, and 4.5um) counterparts for 252 (98.4%) of the 256 Chandra sources, with an estimated reliability of 95%. Finally, we compute the cumulative number of sources in each X-ray band, finding that they are in general agreement with the results from the Chandra Deep Fields.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/654/115
- Title:
- DEEP2 Galaxy Redshift Survey: SDSS QSOs
- Short Name:
- J/ApJ/654/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the clustering of Deep Extragalactic Evolutionary Probe 2 (DEEP2) galaxies at 0.7<z<1.4 around quasars identified using both the Sloan Digital Sky Survey (SDSS) and DEEP2 surveys. We measure the two-point cross-correlation of a sample of 36 optically selected, spectroscopically identified quasars from the SDSS and 16 more found in the DEEP2 survey with the full DEEP2 galaxy sample over scales 0.1h^-1^MPc<r_p_<10h^-1^Mpc.
- ID:
- ivo://CDS.VizieR/J/ApJS/119/189
- Title:
- Deep Multicolor Survey. IV.
- Short Name:
- J/ApJS/119/189
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This stellar catalog contains 19,494 objects from the Deep Multicolor Survey (DMS) and results from follow-up spectroscopic observations of 234 objects in the catalog. The DMS is based on CCD imaging with the Mayall 4 m telescope in U, B, V, R', I75, and I86 and covers 0.83 deg^2 in six fields at high Galactic latitude. The survey reached 5 sigma limiting magnitudes of 22.1 in I86 to 23.8 in B. The catalog gives positions, magnitudes and error estimates, and classification codes in the six filter bands for all the objects. In addition, the survey is useful for the study of faint field galaxies and of faint stars at high Galactic latitude. Presented are tables that summarize the spectroscopic results for the 55 quasars, 44 compact narrow emission-line galaxies, and 135 stars in the DMS that we have confirmed to date. Also included are illustrations of all the spectra.
- ID:
- ivo://CDS.VizieR/J/AJ/115/1253
- Title:
- Deep X-Ray Radio Blazar Survey (DXRBS). I.
- Short Name:
- J/AJ/115/1253
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have undertaken a survey, the Deep X-Ray Radio Blazar Survey (DXRBS), of archived, pointed ROSAT Position Sensitive Proportional Counter data for blazars by correlating the ROSAT WGACAT database with several publicly available radio catalogs, restricting our candidate list to serendipitous flat radio spectrum sources ({alpha}_r_<=0.70, where S_{nu}_{prop}{nu}^-{alpha}_r_^). We discuss our survey methods, identification procedure, and first results. Our survey is found to be 95% efficient at finding flat-spectrum radio-loud quasars (FSRQs; 59 of our first 85 identifications) and BL Lacertae objects (22 of our first 85 identifications), a figure that is comparable to or greater than that achieved by other radio and X-ray survey techniques. The identifications presented here show that all previous samples of blazars (even when taken together) did not representatively survey the blazar population, missing critical regions of (LX, LR) parameter space within which large fractions of the blazar population lie. Particularly important is the identification of a large population of FSRQs (>=25% of DXRBS FSRQs) with ratios of X-ray to radio luminosity >=10^-6^({alpha}_rx_<=0.78). In addition, as a result of our greater sensitivity, the DXRBS has already more than doubled the number of FSRQs in complete samples with 5GHz (radio) luminosities between 10^31.5^ and 10^33.5^ergs/s/Hz, and fills in the region of parameter space between X-ray-selected and radio-selected samples of BL Lac objects. The DXRBS is the very first sample to contain statistically significant numbers of blazars at low luminosities, approaching what should be the lower end of the FSRQ luminosity function.
- ID:
- ivo://CDS.VizieR/J/MNRAS/323/757
- Title:
- Deep X-Ray Radio Blazar Survey (DXRBS). II.
- Short Name:
- J/MNRAS/323/757
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have searched the archived, pointed ROSAT Position Sensitive Proportional Counter data for blazars by correlating the WGACAT X-ray data base with several publicly available radio catalogues, restricting our candidate list to serendipitous X-ray sources with a flat radio spectrum ({alpha}_r_<=0.70, where S_{nu}_~{nu}^-{alpha}^). his makes up the Deep X-ray Radio Blazar Survey (DXRBS). Here we present new identifications and spectra for 106 sources, including 86 radio-loud quasars, 11 BL Lacertae objects, and nine narrow-line radio galaxies. Together with our previously published objects and already-known sources, our sample now contains 298 identified objects: 234 radio-loud quasars [181 flat-spectrum quasars: FSRQ ({alpha}_r_<=0.50) and 53 steep-spectrum quasars: SSRQ], 36 BL Lacs and 28 narrow-line radio galaxies. Redshift information is available for 96 per cent of these. Thus our selection technique is ~90 per cent efficient at finding radio-loud quasars and BL Lacs. Reaching 5-GHz radio fluxes ~50mJy and 0.1-2.0keV X-ray fluxes a few W10-14erg/cm^2^/s, DXRBS is the faintest and largest flat-spectrum radio sample with nearly complete (~85 per cent) identification.
- ID:
- ivo://CDS.VizieR/J/MNRAS/472/1850
- Title:
- Detecting damped Ly{alpha} absorbers
- Short Name:
- J/MNRAS/472/1850
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We develop an automated technique for detecting damped Ly{alpha} absorbers (DLAs) along spectroscopic lines of sight to quasi-stellar objects (QSOs or quasars). The detection of DLAs in large-scale spectroscopic surveys such as SDSS III sheds light on galaxy formation at high redshift, showing the nucleation of galaxies from diffuse gas. We use nearly 50000 QSO spectra to learn a novel tailored Gaussian process model for quasar emission spectra, which we apply to the DLA detection problem via Bayesian model selection. We propose models for identifying an arbitrary number of DLAs along a given line of sight. We demonstrate our method's effectiveness using a large-scale validation experiment, with excellent performance. We also provide a catalogue of our results applied to 162858 spectra from SDSS-III data release 12.
207. Dislodged AGNs
- ID:
- ivo://CDS.VizieR/J/ApJ/835/L30
- Title:
- Dislodged AGNs
- Short Name:
- J/ApJ/835/L30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate a sample of 2293 ICRF2 extragalactic radio-loud sources with accurate positions determined by VLBI, mostly active galactic nuclei (AGNs) and quasars, which are cross-matched with optical sources in the first Gaia release (Gaia DR1). The distribution of offsets between the VLBI sources and their optical counterparts is strongly non-Gaussian, with powerful wings extending beyond 1 arcsec. Limiting our analysis to only high-confidence difference detections, we find (and publish) a list of 188 objects with normalized variances above 12 and offsets below 1 arcsec. Pan-STARRS stacked and monochromatic images resolve some of these sources, indicating the presence of double sources, confusion sources, or pronounced extended structures. Some 89 high-quality objects, however, do not show any perturbations and appear to be star-like single sources, yet they are displaced by multiples of the expected error from the radio-loud AGN. We conclude that a fraction of luminous AGNs (more than 4%) can be physically dislodged from the optical centers of their parent galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/464/L56
- Title:
- DLA properties and EW of 36 QSOs
- Short Name:
- J/MNRAS/464/L56
- Date:
- 02 Feb 2022 07:22:02
- Publisher:
- CDS
- Description:
- The XQ-100 survey provides optical and near-infrared coverage of 36 blindly selected, intervening damped Lyman {alpha} systems (DLAs) at 2<z_abs_<4, simultaneously covering the MgII doublet at {lambda}{lambda}2796,2803{AA}, and the Ly{alpha} transition. Using the XQ-100 DLA sample, we investigate the completeness of selecting DLA absorbers based on their MgII rest-frame equivalent width (W_0_^2796^) at these redshifts. Of the 29 DLAs with clean Mg II profiles, we find that six (20 per cent of DLAs) have W_0_^2796^<0.6{AA}. The DLA incidence rate of W_0_^2796^<0.6{AA} absorbers is a factor of ~5 higher than what is seen in z~1 samples, indicating a potential evolution in the MgII properties of DLAs with redshift. All of the W_0_^2796^<0.6{AA} DLAs have low metallicities (-2.5<[M/H]<-1.7), small velocity widths (v_90_<50km/s), and tend to have relatively low N(HI). We demonstrate that the exclusion of these low W_0_^2796^ DLAs results in a higher mean N(HI) which in turn leads to an ~7 per cent increase in the cosmological gas density of HI of DLAs at 2<z_abs_<4; and that this exclusion has a minimal effect on the HI-weighted mean metallicity.
- ID:
- ivo://CDS.VizieR/J/A+A/611/A76
- Title:
- DLAS dust-corrected metallicity
- Short Name:
- J/A+A/611/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interpreting abundances of damped Ly-{alpha} absorbers (DLAs) from absorption-line spectroscopy has typically been a challenge because of the presence of dust. Nevertheless, because DLAs trace distant gas-rich galaxies regardless of their luminosity, they provide an attractive way of measuring the evolution of the metallicity of the neutral gas with cosmic time. This has been done extensively so far, but typically not taking proper dust corrections into account. The aims of this paper are to: (i) provide a simplified way of calculating dust corrections, based on a single observed [X/Fe], (ii) assess the importance of dust corrections for DLA metallicities and their evolution, and (iii) investigate the cosmic evolution of iron for a large DLA sample. We have derived dust corrections based on the observed [Zn/Fe], [Si/Fe], or [S/Fe], and confirmed their robustness. We present dust-corrected metallicities in a scale of [Fe/H]tot for 236 DLAs over a broad range of z, and assess the extent of dust corrections for different metals at different metallicities. Dust corrections in DLAs are important even for Zn (typically of 0.1-0.2, and up to 0.5dex), which is often neglected. Finally, we study the evolution of the dust-corrected metallicity with z. The DLA metallicities decrease with redshift, by a factor of 50-100 from today to ~12.6 billion years ago (z=5). When including dust corrections, the average DLA metallicities are 0.4-0.5dex higher than without corrections. The upper envelope of the relation between metallicity and z reaches solar metallicity at z<~0.5, although some systems can have solar metallicity already out to z~3.
210. DLAs in SDSS-DR7
- ID:
- ivo://CDS.VizieR/J/A+A/505/1087
- Title:
- DLAs in SDSS-DR7
- Short Name:
- J/A+A/505/1087
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the evolution of the cosmological mass density of neutral gas using a fully automatic search for Damped Lyman-alpha systems in the Sloan Digital Sky Survey II Data Release 7.
