- ID:
- ivo://CDS.VizieR/J/ApJS/215/12
- Title:
- BOSS narrow CIV absorption lines. II. zem>2.4
- Short Name:
- J/ApJS/215/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As the second work in a series of papers aiming to detect absorption systems in the quasar spectra of the Baryon Oscillation Spectroscopic Survey, we continue the analysis of Paper I (Chen+, 2014, J/ApJS/210/7; 2014ApJS..212...17C) by expanding the quasar sample to those quasars with z_em_>2.4. This yields a sample of 21963 appropriate quasars to search for narrow CIV{lambda}{lambda}1548,1551 absorptions with W_r_>=0.2{AA} for both lines. There are 9708 quasars with at least one appropriate absorption system imprinted on their spectra. From these spectra, we detect 13919 narrow C IV absorption systems whose absorption redshifts cover a range of z_abs_=1.8784-4.3704. In this paper and Paper I, we have selected 37241 appropriate quasars with median S/N>=4 and 1.54<~z_em_<~5.16 to visually analyze narrow CIV{lambda}{lambda}1548,1551 absorption doublets one by one. A total of 15999 quasars are found to have at least one appropriate absorption system imprinted on their spectra. From these 15999 quasar spectra, we have detected 23336 appropriate CIV{lambda}{lambda}1548,1551 absorption systems with W_r_>=0.2{AA} whose absorption redshifts cover a range of z_abs_=1.4544-4.3704. The largest values of W_r_ are 3.19{AA} for the {lambda}1548 absorption line and 2.93{AA} for the {lambda}1551 absorption line, respectively. We find that only a few absorbers show large values of W_r_. About 1.1% of the total absorbers have W_r_{lambda}1548>=2.0{AA}.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/210/7
- Title:
- BOSS narrow CIV absorption lines. I. zem<=2.4
- Short Name:
- J/ApJS/210/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have assembled absorption systems by visually identifying CIV {lambda}{lambda}1548, 1551 absorption doublets in the quasar spectra of the Baryon Oscillation Spectroscopic Survey (BOSS) one by one. This paper is the first of the series of work. In this paper, we focus on quasars with relatively low redshifts and high signal-to-noise ratio spectra, and hence we limit our analysis to quasars with z_em_<=2.4 and to doublets with W_r_{lambda}1548>=0.2{AA}. Out of the more than 87000 quasars in Data Release 9, we limit our search to 10121 quasars that have the appropriate redshifts and spectra with high enough signal-to-noise ratios to identify narrow CIV absorption lines. Among them, 5442 quasars are detected to have at least one CIV {lambda}{lambda}1548, 1551 absorption doublet. We obtain a catalog containing 8368 CIV {lambda}{lambda}1548, 1551 absorption systems, whose redshifts are within z_abs_=1.4544-2.2805. In this catalog, about 33.7% absorbers have 0.2{AA}<=W_r_{lambda}1548<0.5{AA}, about 45.9% absorbers have 0.5{AA}<=W_r_{lambda}1548<1.0{AA}, about 19.2% absorbers have 1.0{AA}<=W_r_{lambda}1548<2.0{AA}, and about 1.2% absorbers have W_r_{lambda}1548>=2.0{AA}.
- ID:
- ivo://CDS.VizieR/J/ApJ/773/14
- Title:
- BOSS: quasar luminosity function
- Short Name:
- J/ApJ/773/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new measurement of the optical quasar luminosity function (QLF), using data from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III: BOSS). From the SDSS-III Data Release Nine, a uniform sample of 22301 i<~21.8 quasars are selected over an area of 2236deg^2^, with confirmed spectroscopic redshifts between 2.2<z<3.5, filling in a key part of the luminosity-redshift plane for optical quasar studies. The completeness of the survey is derived through simulated quasar photometry, and this completeness estimate is checked using a sample of quasars selected by their photometric variability within the BOSS footprint. We investigate the level of systematics associated with our quasar sample using the simulations, in the process generating color-redshift relations and a new quasar K-correction. We probe the faint end of the QLF to M_i_(z=2.2){approx}-24.5 and see a clear break in the QLF at all redshifts up to z=3.5. A log-linear relation (in log{Phi}*-M*) for a luminosity evolution and density evolution model is found to adequately describe our data within the range 2.2<z<3.5; across this interval the break luminosity increases by a factor of ~2.6 while {Phi}* declines by a factor of ~8. At z<~2.2 our data are reasonably well fit by a pure luminosity evolution model, and only a weak signature of "AGN downsizing" is seen, in line with recent studies of the hard X-ray luminosity function. We compare our measured QLF to a number of theoretical models and find that models making a variety of assumptions about quasar triggering and halo occupation can fit our data over a wide range of redshifts and luminosities.
- ID:
- ivo://CDS.VizieR/J/ApJ/648/250
- Title:
- Bright Ages Survey. II.
- Short Name:
- J/ApJ/648/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Bright Ages Survey is a K-band-selected redshift survey over six separate fields with UBVRIzJHK imaging covering a total of 75.6arcmin^2^ and reaching K=20-20.5. Two fields have deep HST imaging, while all are centered on possible overdensities in the range. Here we report photometric redshifts and spectroscopy for this sample, which has been described in Paper I (Colbert et al., 2006ApJ...638..603C).
- ID:
- ivo://CDS.VizieR/J/ApJ/889/189
- Title:
- Brightest high-z galaxies in RELICS clusters
- Short Name:
- J/ApJ/889/189
- Date:
- 17 Jan 2022 00:21:16
- Publisher:
- CDS
- Description:
- Massive foreground galaxy clusters magnify and distort the light of objects behind them, permitting a view into both the extremely distant and intrinsically faint galaxy populations. We present here the z~6-8 candidate high-redshift galaxies from the Reionization Lensing Cluster Survey (RELICS), a Hubble and Spitzer Space Telescope survey of 41 massive galaxy clusters spanning an area of ~200arcmin^2^. These clusters were selected to be excellent lenses, and we find similar high-redshift sample sizes and magnitude distributions as the Cluster Lensing And Supernova survey with Hubble (CLASH). We discover 257, 57, and eight candidate galaxies at z~6, 7, and 8 respectively, (322 in total). The observed (lensed) magnitudes of the z~6 candidates are as bright as AB mag ~23, making them among the brightest known at these redshifts, comparable with discoveries from much wider, blank-field surveys. RELICS demonstrates the efficiency of using strong gravitational lenses to produce high-redshift samples in the epoch of reionization. These brightly observed galaxies are excellent targets for follow-up study with current and future observatories, including the James Webb Space Telescope.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/81
- Title:
- Bright metal-poor stars from HES Survey. II.
- Short Name:
- J/ApJ/835/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtain estimates of stellar atmospheric parameters for a previously published sample of 1777 relatively bright (9<B<14) metal-poor candidates from the Hamburg/ESO Survey. The original Frebel+ (2006, J/ApJ/652/1585; Paper I) analysis of these stars was able to derive estimates of [Fe/H] and [C/Fe] only for a subset of the sample, due to limitations in the methodology then available. A new spectroscopic analysis pipeline has been used to obtain estimates of T_eff_, logg, [Fe/H], and [C/Fe] for almost the entire data set. This sample is very local-about 90% of the stars are located within 0.5kpc of the Sun. We consider the chemodynamical properties of these stars in concert with a similarly local sample of stars from a recent analysis of the Bidelman and MacConnell "weak metal" candidates by Beers+ (2014, J/ApJ/794/58). We use this combined sample to identify possible members of the halo stream of stars suggested by Helmi+ (1999Natur.402...53H) and Chiba & Beers (2000AJ....119.2843C), as well as stars that may be associated with stripped debris from the putative parent dwarf of the globular cluster Omega Centauri, suggested to exist by previous authors. We identify a clear increase in the cumulative frequency of carbon-enhanced metal-poor (CEMP) stars with declining metallicity, as well as an increase in the fraction of CEMP stars with distance from the Galactic plane, consistent with previous results. We also identify a relatively large number of CEMP stars with kinematics consistent with the metal-weak thick-disk population, with possible implications for its origin.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/268
- Title:
- Bright QSOs in Southern Hemisphere (QUBRICS)
- Short Name:
- J/ApJ/887/268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of absorptions along the lines of sight to bright high-z QSOs is an invaluable cosmological tool that provides a wealth of information on the inter-/circum-galactic medium, dark matter, primordial elements, reionization, fundamental constants, and general relativity. Unfortunately, the number of bright (i<~18) QSOs at z>~2 in the southern hemisphere is much lower than that in the north, due to the lack of wide multiwavelength surveys at decl. {delta}<0{deg}, hampering the effectiveness of observations from southern observatories. In this work we present a new method based on Canonical Correlation Analysis to identify such objects, taking advantage of a number of available databases: Skymapper, Gaia DR2, WISE, and 2MASS. Our QSO candidate sample lists 1476 sources with i<18 over 12400deg^2^ in the southern hemisphere. With a preliminary campaign we observed spectroscopically 69 of them, confirming 54 new bright QSOs at z>2.5, corresponding to a success rate of our method of ~80%. Furthermore, we estimate a completeness of ~90% of our sample at completion of our observation campaign. The new QSOs confirmed by this first and the forthcoming campaigns (QUBRICS survey) will be the targets of subsequent studies using higher resolution spectrographs, like ESPRESSO, UVES, and (in the long term) ELT/HIRES.
- ID:
- ivo://CDS.VizieR/J/MNRAS/384/775
- Title:
- Bright Source Sample of AT20G Survey
- Short Name:
- J/MNRAS/384/775
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Australia Telescope 20-GHz (AT20G) Survey is a blind survey of the whole southern sky at 20GHz (with follow-up observations at 4.8 and 8.6GHz) carried out with the Australia Telescope Compact Array from 2004 to 2007. The Bright Source Sample (BSS) is a complete flux-limited subsample of the AT20G Survey catalogue comprising 320 extragalactic (|b|>1.5{deg}) radio sources south of DE=-15{deg} with S_20GHz_>0/50Jy. Of these, 218 have near simultaneous observations at 8 and 5GHz. In this paper we present an analysis of radio spectral properties in total intensity and polarization, size, optical identifications and redshift distribution of the BSS sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/838/73
- Title:
- Brown dwarf surface gravities with Keck/NIRSPEC
- Short Name:
- J/ApJ/838/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine 131 new medium-resolution (R~2000) J-band spectra of M, L, and T dwarfs from the Keck NIRSPEC Brown Dwarf Spectroscopic Survey (BDSS) with 97 previously published BDSS spectra to study surface-gravity-sensitive indices for 228 low-mass stars and brown dwarfs spanning spectral types M5-T9. Specifically, we use an established set of spectral indices to determine surface gravity classifications for all of the M6-L7 objects in our sample by measuring the equivalent widths (EW) of the K I lines at 1.1692, 1.1778, and 1.2529{mu}m, and the 1.2{mu}m FeH_J_ absorption index. Our results are consistent with previous surface gravity measurements, showing a distinct double peak-at ~L5 and T5-in K I EW as a function of spectral type. We analyze the K I EWs of 73 objects of known ages and find a linear trend between log(Age) and EW. From this relationship, we assign age ranges to the very low gravity, intermediate gravity, and field gravity designations for spectral types M6-L0. Interestingly, the ages probed by these designations remain broad, change with spectral type, and depend on the gravity-sensitive index used. Gravity designations are useful indicators of the possibility of youth, but current data sets cannot be used to provide a precise age estimate.
- ID:
- ivo://CDS.VizieR/J/ApJS/196/11
- Title:
- Bulge+disk decompositions of SDSS galaxies
- Short Name:
- J/ApJS/196/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform two-dimensional, point-spread-function-convolved, bulge+disk decompositions in the g and r bandpasses on a sample of 1123718 galaxies from the Legacy area of the Sloan Digital Sky Survey Data Release Seven. Four different decomposition procedures are investigated which make improvements to sky background determinations and object deblending over the standard SDSS procedures that lead to more robust structural parameters and integrated galaxy magnitudes and colors, especially in crowded environments. We use a set of science-based quality assurance metrics, namely, the disk luminosity-size relation, the galaxy color-magnitude diagram, and the galaxy central (fiber) colors to show the robustness of our structural parameters. The best procedure utilizes simultaneous, two-bandpass decompositions. Bulge and disk photometric errors remain below 0.1mag down to bulge and disk magnitudes of g~19 and r~18.5. We also use and compare three different galaxy fitting models: a pure Sersic model, an n_b_=4 bulge+disk model, and a Sersic (free n_b_) bulge+disk model. The most appropriate model for a given galaxy is determined by the F-test probability. All three catalogs of measured structural parameters, rest-frame magnitudes, and colors are publicly released here.