- ID:
- ivo://CDS.VizieR/J/MNRAS/392/19
- Title:
- The 2dF-SDSS QSO survey
- Short Name:
- J/MNRAS/392/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the final spectroscopic QSO catalogue from the 2dF-SDSS LRG (luminous red galaxy) and QSO (2SLAQ) survey. This is a deep, 18<g<21.85 (extinction corrected), sample aimed at probing in detail the faint end of the broad line active galactic nuclei luminosity distribution at z<=2.6. The candidate QSOs were selected from SDSS photometry and observed spectroscopically with the 2dF spectrograph on the Anglo-Australian Telescope. This sample covers an area of 191.9 deg2 and contains new spectra of 16326 objects, of which 8764 are QSOs and 7623 are newly discovered [the remainder were previously identified by the 2dF QSO Redshift Survey (2QZ) and SDSS]. The full QSO sample (including objects previously observed in the SDSS and 2QZ surveys) contains 12702 QSOs. The new 2SLAQ spectroscopic data set also contains 2343 Galactic stars, including 362 white dwarfs, and 2924 narrow emission-line galaxies with a median redshift of z=0.22.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/863/144
- Title:
- The ELQS in SDSS footprint. II. North Gal. Cap
- Short Name:
- J/ApJ/863/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the North Galactic Cap sample of the Extremely Luminous Quasar Survey (ELQS-N), which targets quasars with M_1450_{<}-27 at 2.8<=z<5 in an area of ~7600deg^2^ of the Sloan Digital Sky Survey (SDSS) footprint with 90{deg}<RA<270{deg}. Based on a near-infrared/infrared JKW2 color cut, the ELQS selection efficiently uses random forest methods to classify quasars and to estimate photometric redshifts; this scheme overcomes some of the difficulties of pure optical quasar selection at z~3. As a result, we retain a completeness of >70% over z~3.0-5.0 at m_i_<~17.5, limited toward fainter magnitudes by the depth of the Two Micron All Sky Survey. The presented quasar catalog consists of a total of 270 objects, of which 39 are newly identified in this work with spectroscopy obtained at the Vatican Advanced Technology Telescope and the MMT 6.5m telescope. In addition to the high completeness, which allowed us to discover new quasars in the already well-surveyed SDSS North Galactic Cap, the efficiency of our selection is relatively high at ~79%. Using 120 objects of this quasar sample we are able to extend the previously measured optical quasar luminosity function (QLF) by one magnitude toward the bright end at 2.8<=z<=4.5. A first analysis of the QLF suggests a relatively steep bright-end slope of {beta}~-4 for this sample. This result contrasts with previous results in the same redshift range, which find a much flatter slope around {beta}~-2.5, but agrees with recent measurements of the bright-end slope at lower and higher redshifts. Our results constrain the bright-end slope at z=2.8-4.5 to {beta}{<}-2.94 with a 99% confidence.
- ID:
- ivo://CDS.VizieR/J/ApJS/243/5
- Title:
- The ELQS in the PS1 footprint (PS-ELQS)
- Short Name:
- J/ApJS/243/5
- Date:
- 08 Mar 2022 13:10:17
- Publisher:
- CDS
- Description:
- We present the results of the Extremely Luminous Quasar Survey in the 3{pi} survey of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS; PS1). This effort applies the successful quasar selection strategy of the Extremely Luminous Survey in the Sloan Digital Sky Survey footprint (~12000deg^2^) to a much larger area (~21486deg^2^). This spectroscopic survey targets the most luminous quasars (M_1450_<=-26.5; m_i_<=18.5) at intermediate redshifts (z>=2.8). Candidates are selected based on a near-infrared JKW2 color cut using WISE AllWISE and 2MASS photometry to mainly reject stellar contaminants. Photometric redshifts (z_reg_) and star-quasar classifications for each candidate are calculated from near-infrared and optical photometry using the supervised machine learning technique random forests. We select 806 quasar candidates at z_reg_>=2.8 from a parent sample of 74318 sources. After exclusion of known sources and rejection of candidates with unreliable photometry, we have taken optical identification spectra for 290 of our 334 good PS-ELQS candidates. We report the discovery of 190 new z>=2.8 quasars and an additional 28 quasars at lower redshifts. A total of 44 good PS-ELQS candidates remain unobserved. Including all known quasars at z>=2.8, our quasar selection method has a selection efficiency of at least 77%. At lower declinations, -30<=DEC<=0, we approximately treble the known population of extremely luminous quasars. We provide the PS-ELQS quasar catalog with a total of 592 luminous quasars (m_i_<=18.5, z>=2.8). This unique sample will not only be able to provide constraints on the volume density and quasar clustering of extremely luminous quasars, but also offers valuable targets for studies of the intergalactic medium.
- ID:
- ivo://CDS.VizieR/J/AJ/112/407
- Title:
- The FIRST bright QSO survey
- Short Name:
- J/AJ/112/407
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The FIRST radio survey provides a new resource for constructing a large quasar sample. With source positions accurate to better than 1" and a point source sensitivity limit of 1mJy, it reaches 50 times deeper than previous radio catalogs. We report here on the results of the pilot phase for a FIRST Bright Quasar Survey (FBQS). Based on matching the radio catalog from the initial 300{deg}^2^ of FIRST coverage with the optical catalog from the Automated Plate Machine (APM) digitization of Palomar Sky Survey plates, we have defined a sample of 219 quasar candidates brighter than E=17.50. We have obtained optical spectroscopy for 151 of these and classified 25 others from the literature, yielding 69 quasars or Seyfert 1 galaxies, of which 51 are new identifications. The brightest new quasar has an E magnitude of 14.6 and z=0.91; four others are brighter than E=16. The redshifts range from z=0.12 to 3.42. Half of the detected objects are radio quiet with L_21-cm_<10^32.5^ergs/s. We use the results of this pilot survey to establish criteria for the FBQS that will produce a quasar search program which will be 70% efficient and 95% complete to a 21-cm flux density limit of 1.0mJy.
- ID:
- ivo://CDS.VizieR/J/ApJS/126/133
- Title:
- The FIRST bright quasar survey. II.
- Short Name:
- J/ApJS/126/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Very Large Array (VLA) FIRST survey and the Automated Plate Measuring Facility (APM) catalog of the Palomar Observatory Sky Survey I (POSS-I) plates as the basis for constructing a new radio-selected sample of optically bright quasars. This is the first radio-selected sample that is competitive in size with current optically selected quasar surveys. Using only two basic criteria, radio-optical positional coincidence and optical morphology, quasars and BL Lac objects can be identified with 60% selection efficiency; the efficiency increases to 70% for objects fainter than 17 mag. We show that a more sophisticated selection scheme can predict with better than 85% reliability which candidates will turn out to be quasars. This paper presents the second installment of the FIRST Bright Quasar Survey (FBQS), with a catalog of 636 quasars distributed over 2682 deg^2^. The quasar sample is characterized and all spectra are displayed.
- ID:
- ivo://CDS.VizieR/J/ApJS/135/227
- Title:
- The FIRST bright quasar survey. III.
- Short Name:
- J/ApJS/135/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an extension of the FIRST Bright Quasar Survey (FBQS) to the South Galactic cap, and to a fainter optical magnitude limit. Radio source counterparts with SERC R magnitudes brighter than 18.9 which meet the other FBQS criteria are included. We supplement this list with a modest number of additional objects to test our completeness for quasars with extended radio morphologies. The survey covers 589deg^2^ in two equatorial strips in the southern cap. We have obtained spectra for 86% of the 522 candidates and find 321 radio-selected quasars of which 264 are reported here for the first time. A comparison of this fainter sample with the FBQS sample shows the two to be generally similar. Fourteen new broad absorption line (BAL) quasars are included in this sample. When combined with the previously identified BAL quasars in our earlier papers, we can discern a break in the frequency of BAL quasars with radio loudness, namely that the relative number of high-ionization BAL quasars drops by a factor of 4 for quasars with a radio-loudness parameter R*>100.
- ID:
- ivo://CDS.VizieR/J/ApJ/698/1095
- Title:
- The FIRST-2MASS red QSO survey. II.
- Short Name:
- J/ApJ/698/1095
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results on a survey to find extremely dust-reddened Type 1 quasars. Combining the FIRST radio survey, the 2MASS Infrared Survey and the Sloan Digital Sky Survey, we have selected a candidate list of 122 potential red quasars. With more than 80% spectroscopically identified objects, well over 50% are classified as dust-reddened Type 1 quasars, whose reddenings (E(B-V)) range from approximately 0.1 to 1.5mag. They lie well off the color selection windows usually used to detect quasars and many fall within the stellar locus, which would have made it impossible to find these objects with traditional color selection techniques. The reddenings found are much more consistent with obscuration happening in the host galaxy rather than stemming from the dust torus. We find an unusually high fraction of broad absorption line (BAL) quasars at high redshift, all but one of them belonging to the low-ionization BAL (LoBAL) class and many also showing absorption in the metastable FeII line (FeLoBAL). The discovery of further examples of dust-reddened LoBAL quasars provides more support for the hypothesis that BAL quasars (at least LoBAL quasars) represent an early stage in the lifetime of the quasar. The fact that we see such a high fraction of BALs could indicate that the quasar is in a young phase in which quasar feedback from the BAL winds is suppressing star formation in the host galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJS/252/15
- Title:
- The GNRIS-Distant Quasar Survey (GNRIS-DQS)
- Short Name:
- J/ApJS/252/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic measurements for 226 sources from the Gemini Near Infrared Spectrograph-Distant Quasar Survey (GNIRS-DQS). Being the largest uniform, homogeneous survey of its kind, it represents a flux-limited sample (m_i_<~19.0mag, H<~16.5mag) of Sloan Digital Sky Survey (SDSS) quasars at 1.5<~z<~3.5 with a monochromatic luminosity ({lambda}L_{lambda}_) at 5100{AA} in the range of 10^44^-10^46^erg/s. A combination of the GNIRS and SDSS spectra covers principal quasar diagnostic features, chiefly the CIV{lambda}1549, MgII{lambda}{lambda}2798,2803, H{beta}{lambda}4861, and [OIII]{lambda}{lambda}4959,5007 emission lines, in each source. The spectral inventory will be utilized primarily to develop prescriptions for obtaining more accurate and precise redshifts, black hole masses, and accretion rates for all quasars. Additionally, the measurements will facilitate an understanding of the dependence of rest-frame ultraviolet-optical spectral properties of quasars on redshift, luminosity, and Eddington ratio, and test whether the physical properties of the quasar central engine evolve over cosmic time.
- ID:
- ivo://CDS.VizieR/VII/273
- Title:
- The Half Million Quasars (HMQ) catalogue
- Short Name:
- VII/273
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A quasar catalogue is presented with a total of 510764 objects including 424748 type 1 QSOs and 26623 type 1 AGN complete from the literature to 25 January 2015. Also included are 25015 high-confidence SDSS-based photometric quasars with radio/X-ray associations, 1595 BL Lac objects, and 32783 type 2 objects. Each object is displayed with arcsecond-accurate astrometry, red and blue photometry, redshift, citations, and radio and X-ray associations where present. Also, 114 new spectroscopically confirmed quasars are presented.
- ID:
- ivo://CDS.VizieR/J/AJ/160/242
- Title:
- The H{alpha} dots survey. II. 119 new dots
- Short Name:
- J/AJ/160/242
- Date:
- 09 Mar 2022 22:00:00
- Publisher:
- CDS
- Description:
- We present the second catalog of serendipitously discovered compact extragalactic emission-line sources-H{alpha} Dots. These objects have been discovered in searches of moderately deep narrow-band images acquired for the ALFALFA H{alpha} project. In addition to cataloging 119 new H{alpha} Dots, we also present follow-up spectral data for the full sample. These spectra allow us to confirm the nature of these objects as true extragalactic emission-line objects, to classify them in terms of activity type (star-forming or AGN), and to identify the emission line via which they were discovered. We tabulate photometric and spectroscopic data for the all objects, and we present an overview of the properties of the full H{alpha} Dot sample. The H{alpha} Dots represent a broad range of star-forming and active galaxies detected via several different emission lines over a wide range of redshifts. The sample includes H{alpha}-detected blue compact dwarf galaxies at low redshift, [OIII]-detected Seyfert 2 and Green Pea-like galaxies at intermediate redshifts, and QSOs detected via one of several UV emission lines, including Ly{alpha}. Despite the heterogeneous appearance of the resulting catalog of objects, we show that our selection method leads to well-defined samples of specific classes of emission-line objects with properties that allow for statistical studies of each class.
