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191. Damped Lyman{alpha} absorbers in z>4 QSOs
ID:
ivo://CDS.VizieR/J/A+A/508/133
Title:
Damped Lyman{alpha} absorbers in z>4 QSOs
Short Name:
J/A+A/508/133
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a survey of damped (DLA, logN(HI)>20.3) and sub-damped Lyman-{alpha} systems (19.5<logN(HI)<20.3) at z>2.55 along the lines-of-sight to 77 quasars with emission redshifts in the range 4<z_em_<6.3. Intermediate resolution (R~4300) spectra were obtained with the Echellette Spectrograph and Imager (ESI) mounted on the Keck telescope. A total of 100 systems with logN(HI)>19.5 were detected of which 40 systems are damped Lyman-{alpha} systems for an absorption length of {Delta}X= 378. About half of the lines of sight of this homogeneous survey have never been investigated for DLAs.
192. Damped Lyman alpha absorption of QSOs
ID:
ivo://CDS.VizieR/J/other/PASA/19.455
Title:
Damped Lyman alpha absorption of QSOs
Short Name:
J/other/PASA/19.
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalogue of the 322 damped Lyman alpha absorbers taken from the literature. All damped Lyman alpha absorbers are included, with no selection on redshift or quasar magnitude. Of these, 123 are candidates and await confirmation using high resolution spectroscopy. For all 322 objects we catalogue the radio properties of the background quasars, when known. Around 60 quasars have radio flux densities above 0.1Jy and approximately half of these have optical magnitudes brighter than V=18. This compilation should prove useful in several areas of extragalactic/cosmological research.
193. Damped Lyman{alpha} systems
ID:
ivo://CDS.VizieR/J/MNRAS/392/998
Title:
Damped Lyman{alpha} systems
Short Name:
J/MNRAS/392/998
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using a sample of 21 damped Lyman alpha systems (DLAs) and 35 sub-DLAs, we evaluate the D-index=[EW({AA})/{Delta}v(km/s)]x1000 from high-resolution spectra of the MgII {lambda}2796 profile. This sample represents an increase in the sub-DLA statistics by a factor of 4 over the original D-index sample. We investigate various techniques to define the velocity spread ({Delta}v) of the MgII line to determine an optimal D-index for the identification of DLAs. The success rate of DLA identification is 50-55 per cent, depending on the velocity limits used, improving by a few per cent when the column density of FeII is included in the D-index calculation. We recommend the set of parameters that are judged to be most robust, have a combination of high DLA identification rate (57 per cent) and low DLA miss rate (6 per cent) and most cleanly separate the DLAs and sub-DLAs (Kolmogorov-Smirnov probability 0.5 per cent). These statistics demonstrate that the D-index is the most efficient technique for selecting low-redshift DLA candidates.
194. Damped Lyman Alpha systems equivalent width
ID:
ivo://CDS.VizieR/J/MNRAS/471/3428
Title:
Damped Lyman Alpha systems equivalent width
Short Name:
J/MNRAS/471/3428
Date:
21 Oct 2021
Publisher:
CDS
Description:
We derive the statistical properties of neutral gas at redshifts 0.11<z<1.65 from ultraviolet (UV) measurements of quasar Ly{alpha} absorption lines corresponding to 369 MgII systems with W{lambda}2796_0_>=0.3{AA}. In addition to the 41 damped Lyman alpha (DLA) systems presented in Rao et al. (2006ApJ...636..610R, Cat. J/ApJ/636/610), the current DLA sample includes 29 newly discovered DLAs. Formally, this DLA sample includes 70 systems with N_HI_>=2*10^20^atoms/cm^2^. We find that the incidence of DLAs, or the product of their gas cross-section and their comoving number density, can be described by n_DLA_(z)=(0.027+/-0.007)(1+z)^(1.682+/-0.200)^ over the redshift range of 0<z<5. The cosmic mass density of neutral gas can be described by {Omega}_DLA_(z)=(4.77+/-1.60)x10^-4^(1+z)^(0.64+/-0.27)^. The low-redshift column density distribution function is well fitted by a power law of the form f(N)~N^{beta}^ with {beta}=-1.46+/-0.20. It is consistent with the high redshift as well as z=0 estimates at the high-column density end but lies between them at the low-column density end. We discuss possible N_HI_ and metallicity bias in Mg II-selected DLA samples and show that such biases do not exist in the current data at z<1.65. Thus, at least at z<1.65, DLAs found through MgII selection statistically represent the true population of DLAs. However, we caution that studies of DLA metallicities should take into account the relative incidence of DLAs with respect to W_0_{lambda}2796^ (or gas velocity spread) in order to
195. Deep CFHT imaging of VVDS-F22 field. II. Quasars
ID:
ivo://CDS.VizieR/J/AJ/155/110
Title:
Deep CFHT imaging of VVDS-F22 field. II. Quasars
Short Name:
J/AJ/155/110
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of a faint quasar survey in a one-square-degree field. The aim is to test the Y-K/g-z and J-K/i-Y color selection criteria for quasars at faint magnitudes to obtain a complete sample of quasars based on deep optical and near-infrared color-color selection and to measure the faint end of the quasar luminosity function (QLF) over a wide redshift range. We carried out a quasar survey based on the Y-K/g-z and J-K/i-Y quasar selection criteria, using the deep Y-band data obtained from our CFHT/WIRCam Y-band images in a two-degree field within the F22 field of the VIMOS VLT deep survey, optical co-added data from Sloan Digital Sky Survey Stripe 82 and deep near-infrared data from the UKIDSS Deep Extragalactic Survey in the same field. We discovered 25 new quasars at 0.5<z<4.5 and i<22.5 mag within one-square-degree field. The survey significantly increases the number of faint quasars in this field, especially at z~2-3. It confirms that our color selections are highly complete in a wide redshift range (z<4.5), especially over the quasar number density peak at z~2-3, even for faint quasars. Combining all previous known quasars and new discoveries, we construct a sample with 109 quasars and measure the binned QLF and parametric QLF. Although the sample is small, our results agree with a pure luminosity evolution at lower redshift and luminosity evolution and density evolution model at redshift z>2.5.
196. Deep Chandra survey in J1030+0524 field
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.
197. DEEP2 Galaxy Redshift Survey: SDSS QSOs
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.
198. Deep Multicolor Survey. IV.
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.
199. Deep X-Ray Radio Blazar Survey (DXRBS). I.
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.
200. Deep X-Ray Radio Blazar Survey (DXRBS). II.
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.