- ID:
- ivo://CDS.VizieR/J/AJ/127/2455
- Title:
- Gemini Deep Deep Survey (GDDS)
- Short Name:
- J/AJ/127/2455
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gemini Deep Deep Survey (GDDS) is an ultradeep (K<20.6mag, I<24.5mag) redshift survey targeting galaxies in the "redshift desert" between z=1 and z=2. The primary goal of the survey is to constrain the space density at high redshift of evolved high-mass galaxies. We obtained 309 spectra in four widely separated 30-arcmin^2^ fields using the Gemini North telescope and the Gemini Multi-Object Spectrograph (GMOS). The spectra define a one-in-two sparse sample of the reddest and most luminous galaxies near the I-K versus I color-magnitude track mapped out by passively evolving galaxies in the redshift interval 0.8<z<1.8. This sample is augmented by a one-in-seven sparse sample of the remaining high-redshift galaxy population. The GMOS spectrograph was operating in a nod-and-shuffle mode, which enabled us to remove sky contamination with high precision, even for typical exposures times of 20-30hr per field. The resulting spectra are the deepest ever obtained. In this paper we present our sample of 309 spectra, along with redshifts, identifications of spectral features, and photometry. This makes the GDDS the largest and most complete infrared-selected survey probing the redshift desert. The seven-band (VRIz'JHK_s_) photometry is taken from the Las Campanas Infrared Survey (Cat. <VII/228>).
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/873/35
- Title:
- Gemini GNIRS NIR spectroscopy of 50 QSOs at z>~5.7
- Short Name:
- J/ApJ/873/35
- Date:
- 19 Jan 2022 09:09:09
- Publisher:
- CDS
- Description:
- We report initial results from a large Gemini program to observe z>~5.7 quasars with GNIRS near-IR spectroscopy. Our sample includes 50 quasars with simultaneous ~0.85-2.5{mu}m spectra covering the rest-frame ultraviolet and major broad emission lines from Ly{alpha} to MgII. We present spectral measurements for these quasars and compare with their lower redshift counterparts at z=1.5-2.3. We find that when quasar luminosity is matched, there are no significant differences between the rest-UV spectra of z>~5.7 quasars and the low-z comparison sample. High-z quasars have similar continuum and emission line properties and occupy the same region in the black hole mass and luminosity space as the comparison sample, accreting at an average Eddington ratio of ~0.3. There is no evidence for super-Eddington accretion or hypermassive (>10^10^M_{sun}_) black holes within our sample. We find a mild excess of quasars with weak CIV lines relative to the control sample. Our results, corroborating earlier studies but with better statistics, demonstrate that these high-z quasars are already mature systems of accreting supermassive black holes operating with the same physical mechanisms as those at lower redshifts.
- ID:
- ivo://CDS.VizieR/J/AJ/156/224
- Title:
- Gemini/HST GCP: galaxies in 4 massive clusters
- Short Name:
- J/AJ/156/224
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to study stellar populations and galaxy structures at intermediate and high redshift (z=0.2-2.0) and link these properties to those of low-redshift galaxies, there is a need for well-defined local reference samples. Especially for galaxies in massive clusters, such samples are often limited to the Coma cluster galaxies. We present consistently calibrated velocity dispersions and absorption-line indices for galaxies in the central 2 R_500_x2 R_500_ of four massive clusters at z<0.1: Abell 426/Perseus, Abell 1656/Coma, Abell 2029, and Abell 2142. The measurements are based on data from the Gemini Observatory, McDonald Observatory, and Sloan Digital Sky Survey. For bulge-dominated galaxies, the samples are 95% complete in Perseus and Coma and 74% complete in A2029 and A2142, to a limit of M_B,abs_=<-18.5 mag. The data serve as the local reference for our studies of galaxy populations in the higher-redshift clusters that are part of the Gemini/HST Galaxy Cluster Project (GCP). We establish the scaling relations between line indices and velocity dispersions as a reference for the GCP. We derive stellar population parameters, ages, metallicities [M/H], and abundance ratios from line indices, both averaged in bins of velocity dispersion and from individual measurements for galaxies in Perseus and Coma. The zero points of relations between the stellar population parameters and the velocity dispersions limit the allowed cluster-to-cluster variation of the four clusters to +/-0.08 dex in age, +/-0.06 dex in [M/H], +/-0.07 dex in [CN/Fe], and +/-0.03 dex in [Mg/Fe].
- ID:
- ivo://CDS.VizieR/J/ApJ/901/123
- Title:
- Ghostly damped Ly{alpha} systems in SDSS DR14
- Short Name:
- J/ApJ/901/123
- Date:
- 18 Feb 2022 09:18:37
- Publisher:
- CDS
- Description:
- We report the discovery of 59 new ghostly absorbers from the Sloan Digital Sky Survey Data Release 14. These absorbers, with z_abs_~z_QSO_, reveal no Ly{alpha} absorption, and they are mainly identified through the detection of strong metal absorption lines in the spectra. The number of such previously known systems is 30. The new systems are found with the aid of machine-learning algorithms. The spectra of 41 (out of total of 89) absorbers also cover the Ly{beta} spectral region. By fitting the damping wings of the Ly{beta} absorption in the stacked spectrum of 21 (out of 41) absorbers with relatively stronger Ly{beta} absorption, we measured an HI column density of log N(HI)=21.50. This column density is 0.5dex higher than that of the previous work. We also found that the metal absorption lines in the stacked spectrum of the 21 ghostly absorbers with stronger Ly{beta} absorption have similar properties as those in the stacked spectrum of the remaining systems. This circumstantial evidence strongly suggests that the majority of our ghostly absorbers are indeed DLAs.
- ID:
- ivo://CDS.VizieR/J/ApJ/888/85
- Title:
- Ghostly strong Lya absorbers in SDSS DR12
- Short Name:
- J/ApJ/888/85
- Date:
- 25 Oct 2021 10:15:53
- Publisher:
- CDS
- Description:
- We have searched the Sloan Digital Sky Survey Data Release 12 for ghostly strong Ly{alpha} (DLA) systems. These systems, located at the redshift of the quasars, show strong absorption from low-ionization atomic species but reveal no HI Ly{alpha} absorption. Our search has, for the first time, resulted in a sample of 30 homogeneously selected ghostly absorbers with z_QSO_>2.0. Thirteen of the ghostly absorbers exhibit absorption from other HI Lyman series lines. The lack of Ly{alpha} absorption in these absorbers is consistent with them being dense and compact with projected sizes smaller than the broad-line region of the background quasar. Although uncertain, the estimated median HI column density of these absorbers is logN(HI)~21.0. We compare the properties of ghostly absorbers with those of eclipsing DLAs that are high-column-density absorbers, located within 1500km/s of the quasar emission redshift and showing strong Ly{alpha} emission in their DLA trough. We discover an apparent sequence in the observed properties of these DLAs, with ghostly absorbers showing wider HI kinematics, stronger absorptions from high-ionization species, CII and SiII excited states, and a higher level of dust extinction. Since we estimate that all these absorbers have similar metallicities, logZ/Z_{sun}_~-1.0, we conclude that ghostly absorbers are part of the same population as eclipsing DLAs, except that they are denser and located closer to the central active galactic nuclei.
- ID:
- ivo://CDS.VizieR/J/ApJ/740/59
- Title:
- 1.4GHz and X-ray sources in 12 clusters of galaxies
- Short Name:
- J/ApJ/740/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Chandra imaging spectroscopy and Very Large Array (VLA) L-band radio maps, we have identified radio sources at P_1.4GHz_>=5x10^23^W/Hz and X-ray point sources (XPSs) at L_0.3-8keV_>=5x10^42^erg/s in L>L* galaxies in 12 high-redshift (0.4<z<1.2) clusters of galaxies. The radio galaxies and XPSs in this cluster sample, chosen to be consistent with Coma Cluster progenitors at these redshifts, are compared to those found at low-z analyzed in Hart et al. (Paper I, 2009ApJ...705..854H). Within a projected radius of 1Mpc of the cluster cores, we find 17 cluster radio galaxies (11 with secure redshifts, including one luminous FR II radio source at z=0.826, and six more with host galaxy colors similar to cluster ellipticals). Within this same projected radius, we identify seven spectroscopically confirmed cluster XPSs, all with cluster red-sequence (CRS) host galaxy colors. Consistent with the results from Martini et al. (2009ApJ...701...66M), we estimate a minimum X-ray active fraction of 1.4%+/-0.8% for cluster red-sequence galaxies in high-z clusters, corresponding to an approximate 10-fold increase from 0.15%+/-0.15% at low-z. Although complete redshift information is lacking for several XPSs in z>0.4 cluster fields, the increased numbers and luminosities of the CRS radio galaxies and XPSs suggest a substantial (9-10-fold) increase in the heat injected into high-redshift clusters by AGNs compared to the present epoch.
- ID:
- ivo://CDS.VizieR/J/ApJ/831/168
- Title:
- 6GHz JVLA observations of low-z SDSS quasars
- Short Name:
- J/ApJ/831/168
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss 6GHz JVLA observations covering a volume-limited sample of 178 low-redshift (0.2<z<0.3) optically selected quasi-stellar objects (QSOs). Our 176 radio detections fall into two clear categories: (1) about 20% are radio-loud QSOs (RLQs) with spectral luminosities of L_6_>~10^23.2^W/Hz that are primarily generated in the active galactic nucleus (AGN) responsible for the excess optical luminosity that defines a bona fide QSO; and (2) the remaining 80% that are radio-quiet QSOs (RQQs) that have 10^21^<~L_6_<~10^23.2^W/Hz and radio sizes <~10kpc, and we suggest that the bulk of their radio emission is powered by star formation in their host galaxies. "Radio-silent" QSOs (L_6_<~10^21^W/Hz) are rare, so most RQQ host galaxies form stars faster than the Milky Way; they are not "red and dead" ellipticals. Earlier radio observations did not have the luminosity sensitivity of L_6_<~10^21^W/Hz that is needed to distinguish between such RLQs and RQQs. Strong, generally double-sided radio emission spanning >>10kpc was found to be associated with 13 of the 18 RLQ cores with peak flux densities of S_p_>5mJy/beam (log(L)>~24). The radio luminosity function of optically selected QSOs and the extended radio emission associated with RLQs are both inconsistent with simple "unified" models that invoke relativistic beaming from randomly oriented QSOs to explain the difference between RLQs and RQQs. Some intrinsic property of the AGNs or their host galaxies must also determine whether or not a QSO appears radio-loud.
- ID:
- ivo://CDS.VizieR/J/A+A/364/391
- Title:
- 86GHz VLBI survey of compact radio sources
- Short Name:
- J/A+A/364/391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table1 contains the list of observed sources, providing the source coordinates (J2000) and redshift, detection status, type, optical magnitude, and brightness temperature of the radio emission. File table4 contains the description of the VLBI data, and provide the observed total and correlated flux densities, the parameters of single gaussian component model fits, and the parameters of hybrid images of the observed sources. File table5 contains multicomponent model fits for the sources with detected extended structures and the brightness temperatures derived from these model fits.
- ID:
- ivo://CDS.VizieR/J/ApJS/253/25
- Title:
- Giant radio quasars from SDSS, FIRST & NVSS
- Short Name:
- J/ApJS/253/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the largest sample of giant radio quasars (GRQs), which are defined as having a projected linear size greater than 0.7Mpc. The sample consists of 272 GRQs, of which 174 are new objects discovered through cross-matching the NRAO Very Large Array Sky Survey and the Sloan Digital Sky Survey 14th Data Release Quasar Catalog (DR14Q) and confirmed using Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio maps. In our analysis we compare the GRQs with 367 smaller, lobe-dominated radio quasars found using our search method, as well as with quasars from the SDSS DR14Q, investigating the parameters characterizing their radio emission (i.e., total and core radio luminosity, radio core prominence), optical properties (black hole masses, accretion rates, distribution in Eigenvector 1 plane) and infrared colors. For the GRQs and smaller radio quasars we find a strong correlation between [OIII] luminosity and radio luminosity at 1.4GHz, indicating a strong connection between radio emission and conditions in the narrow-line region. We spot no significant differences between GRQs and smaller radio quasars, however we show that most extended radio quasars belong to a quasar population of evolved active galactic nuclei with large black hole masses and low accretion rates. We also show that GRQs have bluer W2-W3 colors compared to SDSS quasars with FIRST detections, indicating differences in the structure of the dusty torus.
- ID:
- ivo://CDS.VizieR/J/ApJ/811/29
- Title:
- GLASS. IV. Lensing cluster Abell 2744
- Short Name:
- J/ApJ/811/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a strong and weak lensing reconstruction of the massive cluster Abell 2744, the first cluster for which deep Hubble Frontier Fields (HFF) images and spectroscopy from the Grism Lens-Amplified Survey from Space (GLASS) are available. By performing a targeted search for emission lines in multiply imaged sources using the GLASS spectra, we obtain five high-confidence spectroscopic redshifts and two tentative ones. We confirm one strongly lensed system by detecting the same emission lines in all three multiple images. We also search for additional line emitters blindly and use the full GLASS spectroscopic catalog to test reliability of photometric redshifts for faint line emitters. We see a reasonable agreement between our photometric and spectroscopic redshift measurements, when including nebular emission in photometric redshift estimations. We introduce a stringent procedure to identify only secure multiple image sets based on colors, morphology, and spectroscopy. By combining 7 multiple image systems with secure spectroscopic redshifts (at 5 distinct redshift planes) with 18 multiple image systems with secure photometric redshifts, we reconstruct the gravitational potential of the cluster pixellated on an adaptive grid, using a total of 72 images. The resulting mass map is compared with a stellar mass map obtained from the deep Spitzer Frontier Fields data to study the relative distribution of stars and dark matter in the cluster. We find that the stellar to total mass ratio varies substantially across the cluster field, suggesting that stars do not trace exactly the total mass in this interacting system. The maps of convergence, shear, and magnification are made available in the standard HFF format.
