- ID:
- ivo://org.gavo.dc/apass/q/cone
- Title:
- AAVSO Photometric All Sky Survey (APASS) DR10
- Short Name:
- APASS DR10 cone
- Date:
- 23 Mar 2022 13:13:11
- Publisher:
- The GAVO DC team
- Description:
- AAVSO Photometric All-Sky Survey (APASS), underway since 2010, covers the entire sky from 7.5 < V < 16.5 magnitude, and in the BVugrizY bandpasses. A northern and a southern site are used, each with twin ASA 20cm astrographs and Apogee Aspen CG16m cameras, covering 2.9x2.9 square degrees with 2.6arcsec pixels. Landolt and SDSS standards are used for all-sky solutions, with typical 0.02mag calibration errors on the bright end. Data Release 10 is a complete reprocessing of all 500K images taken with the system, including hundreds of nights not part of DR9. Sextractor is used for star finding and centroiding; DAOPHOT is used for aperture photometry; the astrometry.net plate-solving library is used for basic astrometry, supplanted with more precise WCS that utilizes knowledge of the optical train distortions. With these changes, DR10 includes many more stars than prior releases. More information is available at http://www.aavso.org/apass.
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- ID:
- ivo://archive.stsci.edu/catalogs/APASS
- Title:
- AAVSO Photometric All Sky Survey ConeSearch
- Short Name:
- APASS CS
- Date:
- 23 Jul 2020 19:59:03
- Publisher:
- Space Telescope Science Institute Archive
- Description:
- All MAST catalog holdings are available via Cone Search endpoints. This service provides access to the MAST mirror of the AAVSO Photometric All Sky Survey All available missions are listed at http://archive.stsci.edu/vo/mast_services.html.
- ID:
- ivo://CDS.VizieR/J/MNRAS/383/1519
- Title:
- Abell 1367 HI sources from AGES
- Short Name:
- J/MNRAS/383/1519
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 21cm HI line observations of 5x1deg^2^ centred on the local Abell cluster 1367 obtained as part of the Arecibo Galaxy Environment Survey. One hundred sources are detected (79 new HI measurements and 50 new redshifts), more than half belonging to the cluster core and its infalling region. Combining the HI data with Sloan Digital Sky Survey (SDSS) optical imaging, we show that our HI selected sample follows scaling relations similar to the ones usually observed in optically selected samples. Interestingly, all galaxies in our sample appear to have nearly the same baryon fraction independently of their size, surface brightness and luminosity. The most striking difference between HI and optically selected samples resides in their large-scale distribution: whereas optical and X-ray observations trace the cluster core very well, in HI there is almost no evidence of the presence of the cluster. Some implications on the determination of the cluster luminosity function and HI distribution for samples selected at different wavelength are also discussed.
- ID:
- ivo://CDS.VizieR/I/331
- Title:
- Absolute Proper motions Outside the Plane (APOP)
- Short Name:
- I/331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of absolute proper motions and updated positions derived from the same Space Telescope Science Institute digitized Schmidt survey plates utilized for the construction of the Guide Star Catalog II. As special attention was devoted to the absolutization process and removal of position, magnitude and color dependent systematic errors through the use of both stars and galaxies, this release is solely based on plate data outside the galactic plane, i.e. |b|>=27{deg}. The resulting global zero point error is less than 0.6 mas/yr, and the precision better than 4.0mas/yr for objects brighter than R_F_=18.5, rising to 9.0mas/yr for objects with magnitude in the range 18.5<R_F_<20.0. The catalog covers 22,525 square degrees and lists 100,774,153 objects to the limiting magnitude of R_F_~20.8. Alignment with the International Celestial Reference System (ICRS) was made using 1288 objects common to the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths. As a result, the coordinate axes realized by our astrometric data are believed to be aligned with the extragalactic radio frame to within +/-0.2mas at the reference epoch J2000.0. This makes our compilation one of the deepest and densest ICRF-registered astrometric catalogs outside the galactic plane. Although the Gaia mission is poised to set the new standard in catalog astronomy and will in many ways supersede this catalog, the methods and procedures reported here will prove useful to remove astrometric magnitude- and color-dependent systematic errors from the next generation of ground-based surveys reaching significantly deeper than the Gaia catalog.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/11
- Title:
- Absorption features in SDSS. I. MgII abs. doublets
- Short Name:
- J/ApJS/235/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for MgII{lambda}{lambda}2796,2803 narrow absorption doublets in the spectra data around MgII{lambda}2798 emission lines. We obtain 17316 MgII doublets, within the redshift range of 0.3299<=z_abs_<=2.5663. We find that a velocity offset of {upsilon}_r_<6000km/s is a safe boundary to constrain the vast majority of associated Mg ii systems, although we find some doublets at {upsilon}_r_>6000km/s. If associated Mg ii absorbers are defined by {upsilon}_r_<6000km/s, ~33.3% of the absorbers are supposed to be contaminants of intervening systems. Removing the 33.3% contaminants, ~4.5% of the quasars present at least one associated MgII system with W_r_^{lambda}2796^>=0.2{AA}. The fraction of associated MgII systems with high-velocity outflows correlates with the average luminosities of their central quasars, indicating a relationship between outflows and the quasar feedback power. The {upsilon}_r_ distribution of the outflow MgII absorbers is peaked at 1023km/s, which is smaller than the corresponding value of the outflow CIV absorbers. The redshift number density evolution of absorbers (dn/dz) limited by {upsilon}_r_{>}-3000km/s differs from that of absorbers constrained by {upsilon}_r_>2000km/s. Absorbers limited by {upsilon}_r_>2000km/s and higher values exhibit profiles similar to dn/dz. In addition, the dn/dz is smaller when absorbers are constrained with larger {upsilon}_r_. The distributions of equivalent widths, and the ratio of W_r_^{lambda}2796^/W_r_^{lambda}2803^, are the same for associated and intervening systems, and independent of quasar luminosity.
- ID:
- ivo://CDS.VizieR/J/ApJ/798/122
- Title:
- Abundances from SEGUE Stellar Parameters Pipeline
- Short Name:
- J/ApJ/798/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A fundamental challenge for wide-field imaging surveys is obtaining follow-up spectroscopic observations: there are >10^9^ photometrically cataloged sources, yet modern spectroscopic surveys are limited to ~fewx10^6^ targets. As we approach the Large Synoptic Survey Telescope era, new algorithmic solutions are required to cope with the data deluge. Here we report the development of a machine-learning framework capable of inferring fundamental stellar parameters (T_eff_, logg, and [Fe/H]) using photometric-brightness variations and color alone. A training set is constructed from a systematic spectroscopic survey of variables with Hectospec/Multi-Mirror Telescope. In sum, the training set includes ~9000 spectra, for which stellar parameters are measured using the SEGUE Stellar Parameters Pipeline (SSPP). We employed the random forest algorithm to perform a non-parametric regression that predicts T_eff_, logg, and [Fe/H] from photometric time-domain observations. Our final optimized model produces a cross-validated rms error (RMSE) of 165K, 0.39dex, and 0.33dex for T_eff_, logg, and [Fe/H], respectively. Examining the subset of sources for which the SSPP measurements are most reliable, the RMSE reduces to 125K, 0.37dex, and 0.27dex, respectively, comparable to what is achievable via low-resolution spectroscopy. For variable stars this represents a {approx}12%-20% improvement in RMSE relative to models trained with single-epoch photometric colors. As an application of our method, we estimate stellar parameters for ~54000 known variables. We argue that this method may convert photometric time-domain surveys into pseudo-spectrographic engines, enabling the construction of extremely detailed maps of the Milky Way, its structure, and history.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/5
- Title:
- Abundances of LAMOST giants from APOGEE DR12
- Short Name:
- J/ApJ/836/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this era of large-scale spectroscopic stellar surveys, measurements of stellar attributes ("labels," i.e., parameters and abundances) must be made precise and consistent across surveys. Here, we demonstrate that this can be achieved by a data-driven approach to spectral modeling. With The Cannon, we transfer information from the APOGEE survey to determine precise T_eff_, logg, [Fe/H], and [{alpha}/M] from the spectra of 450000 LAMOST giants. The Cannon fits a predictive model for LAMOST spectra using 9952 stars observed in common between the two surveys, taking five labels from APOGEE DR12 as ground truth T_eff_, logg, [Fe/H], [{alpha}/M], and K-band extinction A_k_. The model is then used to infer T_eff_, logg, [Fe/H], and [{alpha}/M] for 454180 giants, 20% of the LAMOST DR2 stellar sample. These are the first [{alpha}/M] values for the full set of LAMOST giants, and the largest catalog of [{alpha}/M] for giant stars to date. Furthermore, these labels are by construction on the APOGEE label scale; for spectra with S/N>50, cross-validation of the model yields typical uncertainties of 70K in T_eff_, 0.1 in logg, 0.1 in [Fe/H], and 0.04 in [{alpha}/M], values comparable to the broadly stated, conservative APOGEE DR12 uncertainties. Thus, by using "label transfer" to tie low-resolution (LAMOST R~1800) spectra to the label scale of a much higher-resolution (APOGEE R~22500) survey, we substantially reduce the inconsistencies between labels measured by the individual survey pipelines. This demonstrates that label transfer with The Cannon can successfully bring different surveys onto the same physical scale.
- ID:
- ivo://CDS.VizieR/J/ApJ/864/91
- Title:
- A compilation of 128 galaxy-galaxy strong-lens systems
- Short Name:
- J/ApJ/864/91
- Date:
- 03 Nov 2021 13:33:10
- Publisher:
- CDS
- Description:
- We propose a new strategy of finding strongly lensed supernovae (SNe) by monitoring known galaxy-scale strong-lens systems. Strongly lensed SNe are potentially powerful tools for the study of cosmology, galaxy evolution, and stellar populations, but they are extremely rare. By targeting known strongly lensed star-forming galaxies, our strategy significantly boosts the detection efficiency for lensed SNe compared to a blind search. As a reference sample, we compile the 128 galaxy-galaxy strong-lens systems from the Sloan Lens ACS Survey (SLACS), the SLACS for the Masses Survey, and the Baryon Oscillation Spectroscopic Survey Emission-Line Lens Survey. Within this sample, we estimate the rates of strongly lensed Type Ia SN (SNIa) and core-collapse SN (CCSN) to be 1.23+/-0.12 and 10.4+/-1.1 events per year, respectively. The lensed SN images are expected to be widely separated with a median separation of 2". Assuming a conservative fiducial lensing magnification factor of 5 for the most highly magnified SN image, we forecast that a monitoring program with a single-visit depth of 24.7mag (5{sigma} point source, r band) and a cadence of 5days can detect 0.49 strongly lensed SNIa event and 2.1 strongly lensed CCSN events per year within this sample. Our proposed targeted-search strategy is particularly useful for prompt and efficient identifications and follow-up observations of strongly lensed SN candidates. It also allows telescopes with small fields of view and limited time to efficiently discover strongly lensed SNe with a pencil-beam scanning strategy.
- ID:
- ivo://CDS.VizieR/J/ApJS/243/21
- Title:
- A complete sample of broad-line AGN from SDSS-DR7
- Short Name:
- J/ApJS/243/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new, complete sample of 14584 broad-line active galactic nuclei (AGNs) at z<0.35 is presented, which are uncovered homogeneously from the complete database of galaxies and quasars observed spectroscopically in the Sloan Digital Sky Survey Seventh Data Release. The stellar continuum is properly removed for each spectrum with significant host absorption line features, and careful analyses of the emission line spectra, particularly in the H{alpha} and H{beta} wavebands, are carried out. The broad Balmer emission line, particularly H{alpha}, is used to indicate the presence of an AGN. The broad H{alpha} lines have luminosities in a range of 10^38.5^-10^44.3^erg/s, and line widths (FWHMs) of 500-34000km/s. The virial black hole masses, estimated from the broad-line measurements, span a range of 10^5.1^-10^10.3^M_{sun}_, and the Eddington ratios vary from -3.3 to 1.3 in logarithmic scale. Other quantities such as multiwavelength photometric properties and flags denoting peculiar line profiles are also included in this catalog. We describe the construction of this catalog and briefly discuss its properties. The catalog is publicly available online. This homogeneously selected AGN catalog, along with the accurately measured spectral parameters, provides the most updated, largest AGN sample data, which will enable further comprehensive investigations of the properties of the AGN population in the low-redshift universe.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/161
- Title:
- A cosmic void catalog of SDSS DR12 BOSS galaxies
- Short Name:
- J/ApJ/835/161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a cosmic void catalog using the large-scale structure galaxy catalog from the Baryon Oscillation Spectroscopic Survey (BOSS). This galaxy catalog is part of the Sloan Digital Sky Survey (SDSS) Data Release 12 and is the final catalog of SDSS-III. We take into account the survey boundaries, masks, and angular and radial selection functions, and apply the ZOBOV (Neyrinck 2008MNRAS.386.2101N) void finding algorithm to the Galaxy catalog. We identify a total of 10643 voids. After making quality cuts to ensure that the voids represent real underdense regions, we obtain 1228 voids with effective radii spanning the range 20-100h^-1^Mpc and with central densities that are, on average, 30% of the mean sample density. We release versions of the catalogs both with and without quality cuts. We discuss the basic statistics of voids, such as their size and redshift distributions, and measure the radial density profile of the voids via a stacking technique. In addition, we construct mock void catalogs from 1000 mock galaxy catalogs, and find that the properties of BOSS voids are in good agreement with those in the mock catalogs. We compare the stellar mass distribution of galaxies living inside and outside of the voids, and find no large difference. These BOSS and mock void catalogs are useful for a number of cosmological and galaxy environment studies.
- ID:
- ivo://CDS.VizieR/J/ApJS/160/272
- Title:
- A CO survey of young planetary nebulae
- Short Name:
- J/ApJS/160/272
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a sensitive survey of young planetary nebulae in the CO J=2-1 line that significantly increases the available data on warm, dense, molecular gas in the early phases of planetary nebula formation. The observations were made using the IRAM 30m telescope with the 3x3 pixel Heterodyne Receiver Array (HERA). The array provides an effective means of discriminating the CO emission of planetary nebulae in the Galactic plane from contaminating emission of interstellar clouds along the line of sight. A total of 110 planetary nebulae were observed in the survey, and 40 were detected. The results increase the number of young planetary nebulae with known CO emission by approximately a factor of 2. The CO spectra yield radial velocities for the detected nebulae, about half of which have uncertain or no velocity measurements at optical wavelengths. The CO profiles range from parabolic to double-peaked, tracing the evolution of structure in the molecular gas. The line widths are significantly larger than on the asymptotic giant branch, and many of the lines show extended wings, which probably result from the effects on the envelopes of high-velocity jets.
- ID:
- ivo://CDS.VizieR/J/ApJS/169/213
- Title:
- ACS Fornax Cluster Survey. I.
- Short Name:
- J/ApJS/169/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fornax Cluster is a conspicuous cluster of galaxies in the southern hemisphere and the second largest collection of early-type galaxies within 20Mpc after the Virgo Cluster. In this paper, we present a brief introduction to the ACS Fornax Cluster Survey - a program to image, in the F475W (g_475_) and F850LP (z_850_) bandpasses, 43 early-type galaxies in Fornax using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. Combined with a companion survey of Virgo, the ACS Virgo Cluster Survey, this represents the most comprehensive imaging survey to date of early-type galaxies in cluster environments in terms of depth, spatial resolution, sample size, and homogeneity. We describe the selection of the program galaxies, their basic properties, and the main science objectives of the survey, which include the measurement of luminosities, colors, and structural parameters for globular clusters associated with these galaxies, an analysis of their isophotal properties and surface brightness profiles, and an accurate calibration of the surface brightness fluctuation distance indicator. Finally, we discuss the data reduction procedures adopted for the survey.
- ID:
- ivo://CDS.VizieR/J/ApJS/153/223
- Title:
- ACS Virgo Cluster Survey. I.
- Short Name:
- J/ApJS/153/223
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Virgo Cluster is the dominant mass concentration in the Local Supercluster and the largest collection of elliptical and lenticular galaxies in the nearby universe. In this paper, we present an introduction to the ACS (Advanced Camera for Surveys) Virgo Cluster Survey: a program to image, in the F475W and F850LP bandpasses (~Sloan g and z), 100 early-type galaxies in the Virgo Cluster using the Advanced Camera for Surveys on the Hubble Space Telescope.
- ID:
- ivo://CDS.VizieR/J/ApJS/154/509
- Title:
- ACS Virgo Cluster Survey. II.
- Short Name:
- J/ApJS/154/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ACS Virgo Cluster Survey is a large program to carry out multicolor imaging of 100 early-type members of the Virgo Cluster using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. Deep F475W and F850LP images (~SDSS g and z) are being used to study the central regions of the program galaxies, their globular cluster systems, and the three-dimensional structure of Virgo itself. In this paper, we describe in detail the data reduction procedures used for the survey, including image registration, drizzling strategies, the computation of weight images, object detection, the identification of globular cluster candidates, and the measurement of their photometric and structural parameters.
- ID:
- ivo://CDS.VizieR/J/ApJ/613/279
- Title:
- ACS Virgo Cluster Survey. III. M87
- Short Name:
- J/ApJ/613/279
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ACIS instrument on board the Chandra X-Ray Observatory has been used to carry out the first systematic study of low-mass X-ray binaries (LMXBs) in M87, the giant elliptical galaxy near the dynamical center of the Virgo Cluster. These images - with a total exposure time of 154 ks - are the deepest X-ray observations yet obtained of M87. We identify 174 X-ray point sources, of which 150 are likely LMXBs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/439/1556
- Title:
- ACT high significance 148 and 218GHz sources
- Short Name:
- J/MNRAS/439/1556
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of 191 extragalactic sources detected by the Atacama Cosmology Telescope (ACT) at 148 and/or 218GHz in the 2008 Southern survey. Flux densities span 14 -1700mJy, and we use source spectral indices derived using ACT-only data to divide our sources into two subpopulations: 167 radio galaxies powered by central active galactic nuclei (AGN) and 24 dusty star-forming galaxies (DSFGs). We cross-identify 97 percent of our sources (166 of the AGN and 19 of the DSFGs) with those in currently available catalogues. When combined with flux densities from the Australia Telescope 20GHz survey and follow-up observations with the Australia Telescope Compact Array, the synchrotron-dominated population is seen to exhibit a steepening of the slope of the spectral energy distribution from 20 to 148GHz, with the trend continuing to 218GHz. The ACT dust-dominated source population has a median spectral index, {alpha}_148-218_, of 3.7^+0.62^_-0.86_, and includes both local galaxies and sources with redshift around 6. Dusty sources with no counterpart in existing catalogues likely belong to a recently discovered subpopulation of DSFGs lensed by foreground galaxies or galaxy groups.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A122
- Title:
- Active deep learning in large spectros. surveys
- Short Name:
- J/A+A/643/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Current archives of the LAMOST telescope contain millions of pipeline-processed spectra that have probably never been seen by human eyes. Most of the rare objects with interesting physical properties, however, can only be identified by visual analysis of their characteristic spectral features. A proper combination of interactive visualisation with modern machine learning techniques opens new ways to discover such objects. We apply active learning classification methods supported by deep convolutional neural networks to automatically identify complex emission-line shapes in multi-million spectra archives. We used the pool-based uncertainty sampling active learning method driven by a custom-designed deep convolutional neural network with 12 layers. The architecture of the network was inspired by VGGNet, AlexNet, and ZFNet, but it was adapted for operating on one-dimensional feature vectors. The unlabelled pool set is represented by 4.1 million spectra from the LAMOST data release 2 survey. The initial training of the network was performed on a labelled set of about 13000 spectra obtained in the 400{AA} wide region around H{alpha} by the 2m Perek telescope of the Ondrejov observatory, which mostly contains spectra of Be and related early-type stars. The differences between the Ondrejov intermediate-resolution and the LAMOST low-resolution spectrographs were compensated for by Gaussian blurring and wavelength conversion. After several iterations, the network was able to successfully identify emission-line stars with an error smaller than 6.5%. Using the technology of the Virtual Observatory to visualise the results, we discovered 1013 spectra of 948 new candidates of emission-line objects in addition to 664 spectra of 549 objects that are listed in SIMBAD and 2644 spectra of 2291 objects identified in an earlier paper of a Chinese group led by Wen Hou. The most interesting objects with unusual spectral properties are discussed in detail.
- ID:
- ivo://org.gavo.dc/ohmaser/q/scs
- Title:
- A Database of Circumstellar OH Masers
- Short Name:
- engels ohmasers
- Date:
- 23 Mar 2022 13:13:07
- Publisher:
- The GAVO DC team
- Description:
- A all-sky compilation of galactic stellar sources observed for OH maser emission in the transitions at 1612, 1665, and 1667 MHz. The database contains OH maser observations selected from the literature . These observations belong to more than 6000 different objects. The database consists of three tables: The main table ("masers"), interferometric followup observations ("maps") and monitoring programs ("monitor").
- ID:
- ivo://org.gavo.dc/ohmaser/q/mapscs
- Title:
- A Database of Circumstellar OH Masers: Interferometric Followups
- Short Name:
- engels oh maps
- Date:
- 23 Mar 2022 13:13:07
- Publisher:
- The GAVO DC team
- Description:
- A all-sky compilation of galactic stellar sources observed for OH maser emission in the transitions at 1612, 1665, and 1667 MHz. The database contains OH maser observations selected from the literature . These observations belong to more than 6000 different objects. The database consists of three tables: The main table ("masers"), interferometric followup observations ("maps") and monitoring programs ("monitor").
- ID:
- ivo://org.gavo.dc/ohmaser/q/monscs
- Title:
- A Database of Circumstellar OH Masers: Monitoring Programs
- Short Name:
- engels oh mon
- Date:
- 23 Mar 2022 13:13:07
- Publisher:
- The GAVO DC team
- Description:
- A all-sky compilation of galactic stellar sources observed for OH maser emission in the transitions at 1612, 1665, and 1667 MHz. The database contains OH maser observations selected from the literature . These observations belong to more than 6000 different objects. The database consists of three tables: The main table ("masers"), interferometric followup observations ("maps") and monitoring programs ("monitor").
- ID:
- ivo://CDS.VizieR/J/ApJ/701/587
- Title:
- A deep HST H-band imaging survey. II. QUEST QSOs
- Short Name:
- J/ApJ/701/587
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results from a deep Hubble Space Telescope (HST) NICMOS H-band imaging survey of 28 z<0.3 QSOs from the Palomar-Green (PG) sample. This program is part of QUEST (Quasar/ULIRG Evolution Study) and complements a similar set of data on 26 highly nucleated ULIRGs presented in Paper I (Veilleux et al. 2006ApJ...643..707V). Our analysis indicates that the fraction of QSOs with elliptical hosts is higher among QSOs with undetected far-infrared (FIR) emission, small infrared excess (L_IR_/L_B_<10), and luminous hosts. The hosts of FIR-faint QSOs show a tendency to have less pronounced merger-induced morphological anomalies and larger QSO-to-host luminosity ratios on average than the hosts of FIR-bright QSOs, consistent with late-merger evolution from FIR-bright to FIR-faint QSOs.
- ID:
- ivo://CDS.VizieR/J/ApJS/104/185
- Title:
- A deep multicolor survey. I.
- Short Name:
- J/ApJS/104/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Kitt Peak National Observatory 4m Mayall telescope to image 0.83 square degrees of sky in six fields at high Galactic latitude in six filters spanning 3000-10000A to magnitude limits ranging from 22.1 to 23.8. We have assembled a catalog of 21375 stellar objects detected in the fields for use primilary in conducting a multicolor search for quasars. This paper describes the data reduction techniques used on the CCD data, the methods used to construct the stellar object catalog, and the simulations performed to understand its completeness and contamination.
- ID:
- ivo://CDS.VizieR/J/ApJ/462/614
- Title:
- A deep multicolor survey. II.
- Short Name:
- J/ApJ/462/614
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Kitt Peak National Observatory 4m Mayall telescope to image 0.83 square degrees of sky in six fields at high galactic latitude in six filters spanning 3000-10000A to magnitude limits ranging from 22.1 to 23.8. As a first use of this database, we have conducted a multicolor survey for quasars. We discuss various methods of selecting outliers in different color-color diagrams and multicolor space that have been used to identify quasars at all redshifts from their colors alone. We discuss the initial results of our program of spectroscopic identification which has so far resulted in the identification of over 40 faint quasars, including one a z>4, a similar number of compact narrow emission-line galaxies, and a number of unusual and potentially interesting stars. We use these spectroscopic results, along with extensive simulations of quasar spectra, to study the efficiency of our candidate selection procedures. Finally, we compare the number counts of our quasars and quasar candidates to the expected numbers based on previous studies of the quasar luminosity function. The agreement of our observations with these expectations is good in most cases. However, we do estimate that our survey contains more quasars with B<21 and z<2.3 than expected from the results published by Koo & Kron in (1988ApJ...325...92K) and more z>3 quasars than expected from the results published by Warren, Hewett & Osmer in (1994ApJ...421..412W), both at the 3 {sigma} level. Additional spectroscopic observations will be required to confirm or refute these excesses.
- ID:
- ivo://CDS.VizieR/J/AJ/114/2269
- Title:
- A deep multicolor survey. III.
- Short Name:
- J/AJ/114/2269
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have made spectroscopic identifications of 39 additional quasar candidates from the Deep Multicolor Survey (DMS) of Hall et al. (1996, Cat. <J/ApJ/462/614>). We have identified 9 new quasars with 0.3<z<2.8 and 16.8<B<21.6, all from the group of candidates with ultraviolet excess (UVX). No new quasars with z>3 were found among the observed candidates selected due to their red (B-R) and (V-R) colors. As a result, there are now 55 confirmed quasars in the survey: 42 with 0.3<z<2, nine with 2<z<3, three with 3<z<4, and 1 at z=4.3. One new quasar, DMS 0059-0055, is very bright with B=16.8 and z=0.3, making its detection by our survey very unexpected. Including this new spectroscopy, the results of the DMS are converging with the predicted space densities of other surveys. In particular, we no longer find an excess of quasars with z<2.3 and B<21 in the survey over predictions based on models by Koo & Kron (1988ApJ...325...92K). Also, the excess in the number of quasars seen at z>3 over predictions based on models by Warren et al. (1994ApJ...421..412W) is less than previously suggested. We also demonstrate the success of our quasar color modeling which is important in assessing the completeness of our survey.
- ID:
- ivo://CDS.VizieR/J/ApJ/728/38
- Title:
- AEGIS: demographics of X-ray and optical AGN
- Short Name:
- J/ApJ/728/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We develop a new diagnostic method to classify galaxies into active galactic nucleus (AGN) hosts, star-forming galaxies, and absorption-dominated galaxies by combining the [OIII]/H{beta} ratio with rest-frame U-B color. This can be used to robustly select AGNs in galaxy samples at intermediate redshifts (z<1). We compare the result of this optical AGN selection with X-ray selection using a sample of 3150 galaxies with 0.3<z<0.8 and I_AB_<22, selected from the DEEP2 Galaxy Redshift Survey and the All-wavelength Extended Groth Strip International Survey. Among the 146 X-ray sources in this sample, 58% are classified optically as emission-line AGNs, the rest as star-forming galaxies or absorption-dominated galaxies. The latter are also known as "X-ray bright, optically normal galaxies" (XBONGs).
- ID:
- ivo://CDS.VizieR/J/ApJS/180/102
- Title:
- AEGIS-X: Chandra deep survey
- Short Name:
- J/ApJS/180/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the EGIS-X survey, a series of deep Chandra ACIS-I observations of the Extended Groth Strip. The survey comprises pointings at eight separate positions, each with nominal exposure of 200ks, covering a total area of approximately 0.67deg^2^ in a strip of length 2 degrees. We describe in detail an updated version of our data reduction and point-source-detection algorithms used to analyze these data. A total of 1325 band-merged sources have been found to a Poisson probability limit of 4x10^-6^, with limiting fluxes of 5.3x10^-21^W/m2 in the soft (0.5-2keV) band and 3.8x10^-19^W/m2 in the hard (2-10keV) band. We present simulations verifying the validity of our source-detection procedure and showing a very small, <1.5%, contamination rate from spurious sources. Optical/NIR counterparts have been identified from the DEEP2, CFHTLS, and Spitzer/Infrared Array Camera (IRAC) surveys of the same region. Using a likelihood ratio method, we find optical counterparts for 76% of our sources, complete to R_AB_=24.1, and, of the 66% of the sources that have IRAC coverage, 94% have a counterpart to a limit of 0.9uJy at 3.6um (m_AB_=23.8). After accounting for (small) positional offsets in the eight Chandra fields, the astrometric accuracy of Chandra positions is found to be 0"8rms; however, this number depends both on the off-axis angle and the number of detected counts for a given source. All data products described in this paper are made available via a public Web site.
- ID:
- ivo://CDS.VizieR/J/ApJS/220/10
- Title:
- AEGIS-X Deep survey of EGS (AEGIS-XD)
- Short Name:
- J/ApJS/220/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of deep Chandra imaging of the central region of the Extended Groth Strip, the AEGIS-X Deep (AEGIS-XD) survey. When combined with previous Chandra observations of a wider area of the strip, AEGIS-X Wide (AEGIS-XW), these provide data to a nominal exposure depth of 800ks in the three central ACIS-I fields, a region of approximately 0.29deg^2^. This is currently the third deepest X-ray survey in existence; a factor ~2-3 shallower than the Chandra Deep Fields (CDFs), but over an area ~3 times greater than each CDF. We present a catalog of 937 point sources detected in the deep Chandra observations, along with identifications of our X-ray sources from deep ground-based, Spitzer, GALEX, and Hubble Space Telescope imaging. Using a likelihood ratio analysis, we associate multiband counterparts for 929/937 of our X-ray sources, with an estimated 95% reliability, making the identification completeness approximately 94% in a statistical sense. Reliable spectroscopic redshifts for 353 of our X-ray sources are available predominantly from Keck (DEEP2/3) and MMT Hectospec, so the current spectroscopic completeness is ~38%. For the remainder of the X-ray sources, we compute photometric redshifts based on multiband photometry in up to 35 bands from the UV to mid-IR. Particular attention is given to the fact that the vast majority the X-ray sources are active galactic nuclei and require hybrid templates. Our photometric redshifts have mean accuracy of {sigma}=0.04 and an outlier fraction of approximately 5%, reaching {sigma}=0.03 with less than 4% outliers in the area covered by CANDELS.
- ID:
- ivo://CDS.VizieR/VIII/84
- Title:
- A final non-redundant catalogue for 7C 151-MHz survey
- Short Name:
- VIII/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a final unified catalogue for the 7C survey at 151 MHz with resolution 70x70cosec(dec) arcsec^2^. This has been constructed by amalgamating the existing catalogues derived from individual fields imaged at this resolution and eliminating redundancy in regions of mutual overlap. This is a non-trivial procedure because the flux in multiple-component sources may be fitted differently on alternative images, owing, for example, to differences in local noise and beam distortion. The final catalogue thus produced contains 43683 sources. Separate final catalogues have been published for the 7C Galactic Plane survey (7CG, see Cat. J/MNRAS/294/607) and the lower-resolution survey of the low-declination strip 9h<RA<16h, 20deg<Dec<35deg (Cat. J/MNRAS/282/779). The individual catalogues for about 40 of the regions contributing to the total have already been published, together with full details of the methodology, in MNRAS or A&AS: Lacy et al. 1995, MNRAS, 276, 614 (=1995MNRAS.276..614L) (#92 below) Visser et al. 1995, A&AS, 110, 419 (=1995A&AS..110..419V) (#93 below) Pooley et al. 1998, MNRAS, 298, 637 (=1998MNRAS.298..637P) (#94-96 below) Riley et al. 1999, MNRAS, 306, 31 (=1999MNRAS.306...31R) (# 1-33 below) and these data are also available via the MRAO website at http://www.mrao.cam.ac.uk/surveys/7C/ Individual catalogues for the remaining 58 regions by Riley et al. (#34-91 below) were released electronically via the MRAO website in November 2001. These include a re-analysis of data originally published in rather a different parametrization by McGilchrist et al. 1990, MNRAS, 246, 110 (=1990MNRAS.246..110M) The regions re-analyzed are those numbered #41,44,59,60,62 and 63 below and they supersede McGilchrist's 1990 publication. The RAxDec coverage, average rms noise, flux density of the faintest source listed and completeness limit for each of the individual regions contributing to the final catalogue are given in the table "regions.dat". 1-sigma errors on the listed source positions may be approximated by: RA..error(arcsec) = SQRT(1.0**2 + (32/SNR)**2) Dec.error(arcsec) = Kcosec(dec) x (RA error) where (approx) K= 1.0 around dec 70, increasing to 1.3 below dec 50, and 1-sigma errors on the listed flux densities may be approximated by: Error on S beam-fitted(Jy) = SQRT(0.03**2 + SNR**-2) x S(Jy) Error on SINT(Jy) = 1.5 x SQRT(0.03**2 + SNR**-2) x SINT(Jy) where SNR, S and SINT correspond to the columns denoted by those names in the byte-by-byte description below. For multi-component sources the SNR for the brightest component is used to estimate the SINT error. For further details of the surveys and data analysis procedures please refer to the published papers referenced at the head of this file and references therein.
- ID:
- ivo://CDS.VizieR/II/231
- Title:
- A Finding List of Faint UV-Bright Stars
- Short Name:
- II/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The survey lists the very blue objects found on the plates taken for the Sandage Two-Color Survey of the Galactic Plane obtained using the Palomar 48 inch Oschin Schmidt telescope. The sources range in U-B color from U-B~-0.1 to U-B~-1.0 and in magnitude from m_B_~10 to ~20.
- ID:
- ivo://CDS.VizieR/II/212A
- Title:
- A Finding List of Faint UV-Bright Stars
- Short Name:
- II/212A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 195 UV-bright stars have been found on two-color 48-inch Schmidt plates centered on the galactic plane, and on one high-latitude plate. This catalog contains sources with (U-B) in the range U-B=0 to U-B=-1.5.
- ID:
- ivo://CDS.VizieR/II/257A
- Title:
- A Finding List of Faint UV-Bright Stars
- Short Name:
- II/257A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The survey lists the very blue objects found on the plates taken for the Sandage Two-Color Survey of the Galactic Plane obtained using the Palomar 48 inch Oschin Schmidt telescope. The sources range in U-B color from U-B~-0.1 to U-B~-1.0 and in magnitude from m_B_~10 to ~20.
- ID:
- ivo://CDS.VizieR/J/AJ/156/241
- Title:
- A first catalog of variable stars measured by ATLAS
- Short Name:
- J/AJ/156/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Asteroid Terrestrial-impact Last Alert System (ATLAS) carries out its primary planetary defense mission by surveying about 13000 deg^2^ at least four times per night. The resulting data set is useful for the discovery of variable stars to a magnitude limit fainter than r~18, with amplitudes down to 0.02 mag for bright objects. Here, we present a Data Release One catalog of variable stars based on analyzing the light curves of 142 million stars that were measured at least 100 times in the first two years of ATLAS operations. Using a Lomb-Scargle periodogram and other variability metrics, we identify 4.7 million candidate variables. Through the Space Telescope Science Institute, we publicly release light curves for all of them, together with a vector of 169 classification features for each star. We do this at the level of unconfirmed candidate variables in order to provide the community with a large set of homogeneously analyzed photometry and to avoid pre-judging which types of objects others may find most interesting. We use machine learning to classify the candidates into 15 different broad categories based on light-curve morphology. About 10% (427000 stars) pass extensive tests designed to screen out spurious variability detections: we label these as "probable" variables. Of these, 214000 receive specific classifications as eclipsing binaries, pulsating, Mira-type, or sinusoidal variables: these are the "classified" variables. New discoveries among the probable variables number 315000, while 141000 of the classified variables are new, including about 10400 pulsating variables, 2060 Mira stars, and 74700 eclipsing binaries.
- ID:
- ivo://CDS.VizieR/J/ApJS/192/6
- Title:
- A GALEX UV imaging survey of nearby galaxies
- Short Name:
- J/ApJS/192/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a GALEX ultraviolet (UV) survey of a complete sample of 390 galaxies within ~11Mpc of the Milky Way. The UV data are a key component of the composite Local Volume Legacy, an ultraviolet-to-infrared imaging program designed to provide an inventory of dust and star formation in nearby spiral and irregular galaxies. The ensemble data set is an especially valuable resource for studying star formation in dwarf galaxies, which comprise over 80% of the sample. We describe the GALEX survey programs that obtained the data and provide a catalog of far-UV (~1500{AA}) and near-UV (~2200{AA}) integrated photometry. General UV properties of the sample are briefly discussed. We compute two measures of the global star formation efficiency, the star formation rate (SFR) per unit HI gas mass, and the SFR per unit stellar mass, to illustrate the significant differences that can arise in our understanding of dwarf galaxies when the FUV is used to measure the SFR instead of H{alpha}.
- ID:
- ivo://CDS.VizieR/J/AJ/161/100
- Title:
- Ages and alpha-abundances of population in K2
- Short Name:
- J/AJ/161/100
- Date:
- 19 Jan 2022 13:30:38
- Publisher:
- CDS
- Description:
- We explore the relationships between the chemistry, ages, and locations of stars in the Galaxy using asteroseismic data from the K2 mission and spectroscopic data from the Apache Point Galactic Evolution Experiment survey. Previous studies have used giant stars in the Kepler field to map the relationship between the chemical composition and the ages of stars at the solar circle. Consistent with prior work, we find that stars with high [{alpha}/Fe] have distinct, older ages in comparison to stars with low [{alpha}/Fe]. We provide age estimates for red giant branch (RGB) stars in the Kepler field, which support and build upon previous age estimates by taking into account the effect of {alpha}-enrichment on opacity. Including this effect for [{alpha}/Fe]-rich stars results in up to 10% older ages for low- mass stars relative to corrected solar mixture calculations. This is a significant effect that Galactic archeology studies should take into account. Looking beyond the Kepler field, we estimate ages for 735 RGB stars from the K2 mission, mapping age trends as a function of the line of sight. We find that the age distributions for low- and high-[{alpha}/Fe] stars converge with increasing distance from the Galactic plane, in agreement with suggestions from earlier work. We find that K2 stars with high [{alpha}/Fe] appear to be younger than their counterparts in the Kepler field, overlapping more significantly with a similarly aged low-[{alpha}/Fe] population. This observation may suggest that star formation or radial migration proceeds unevenly in the Galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/1883
- Title:
- AGES HI sources in NGC 7448
- Short Name:
- J/MNRAS/415/1883
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we describe results from the Arecibo Galaxy Environments Survey (AGES). The survey reaches column densities of ~3x10^18^cm^-2^ and masses of ~10^7^M_{sun}_, over individual regions of order 10deg^2^ in size, out to a maximum velocity of 18000km/s. Each surveyed region is centred on a nearby galaxy, group or cluster, in this instance the NGC 7448 group. Galaxy interactions in the NGC 7448 group reveal themselves through the identification of tidal tails and bridges. We find ~2.5 times more atomic gas in the intergalactic medium than in the group galaxies. We identify five new dwarf galaxies, two of which appear to be members of the NGC 7448 group. This is too small, by roughly an order of magnitude, a number of dwarf galaxies to reconcile observation with theoretical predictions of galaxy formation models. If they had observed this region of the sky in previous wide-area blind HI surveys, HIPASS and ALFALFA, they would have detected only 5 and 43 per cent, respectively, of the galaxies we have detected, missing a large fraction of the atomic gas in this volume.
- ID:
- ivo://CDS.VizieR/J/ApJS/200/8
- Title:
- AGES: the AGN and Galaxy Evolution Survey
- Short Name:
- J/ApJS/200/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The AGN and Galaxy Evolution Survey (AGES) is a redshift survey covering, in its standard fields, 7.7deg^2^ of the Bootes field of the NOAO Deep Wide-Field Survey. The final sample consists of 23745 redshifts. There are well-defined galaxy samples in 10 bands (the B_W_, R, I, J, K, IRAC 3.6, 4.5, 5.8, and 8.0um, and MIPS 24um bands) to a limiting magnitude of I<20mag for spectroscopy. For these galaxies, we obtained 18163 redshifts from a sample of 35200 galaxies, where random sparse sampling was used to define statistically complete sub-samples in all 10 photometric bands. The median galaxy redshift is 0.31, and 90% of the redshifts are in the range 0.085<z<0.66. Active galactic nuclei (AGNs) were selected as radio, X-ray, IRAC mid-IR, and MIPS 24um sources to fainter limiting magnitudes (I<22.5mag for point sources). Redshifts were obtained for 4764 quasars and galaxies with AGN signatures, with 2926, 1718, 605, 119, and 13 above redshifts of 0.5, 1, 2, 3, and 4, respectively. We detail all the AGES selection procedures and present the complete spectroscopic redshift catalogs and spectral energy distribution decompositions. Photometric redshift estimates are provided for all sources in the AGES samples.
- ID:
- ivo://CDS.VizieR/J/A+AS/65/267
- Title:
- A 5-GHz Survey of Radio Sources
- Short Name:
- J/A+AS/65/267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a sensitive radio survey of about 0.04 sr of extragalactic sky in a narrow strip about declination = +33 deg are reported. The measurements were made with the NRAO 91-meter Green Bank telescope at a frequency of 4760 MHz. A catalogue of the 882 sources detected above a flux density of 15 mJy is given. The area surveyed is part of that covered earlier by the NRAO 5-GHz Survey of Faint Sources, Davis (1971). The results will allow an unbiased study of the variability characteristics of sources common to both surveys.
- ID:
- ivo://CDS.VizieR/J/A+A/558/A137
- Title:
- AGILE bright gamma-ray sources updated list
- Short Name:
- J/A+A/558/A137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a variability study of a sample of bright {gamma}-ray (30MeV-50GeV ) sources. This sample is an extension of the first AGILE catalogue of -ray sources (1AGL), obtained using the complete set of AGILE observations in pointing mode performed during a 2.3 year period from July 9, 2007 until October 30, 2009. The dataset of AGILE pointed observations covers a long time interval and its {gamma}-ray data archive is useful for monitoring studies of medium-to-high brightness {gamma}-ray sources. In the analysis reported here, we used data obtained with an improved event filter that covers a wider field of view, on a much larger (about 27.5 months) dataset, integrating data on observation block time scales, which mostly range from a few days to thirty days. The data processing resulted in a better characterized source list than 1AGL was, and includes 54 sources, 7 of which are new high galactic latitude (|BII|>=5) sources, 8 are new sources on the galactic plane, and 20 sources from the previous catalogue with revised positions. Eight 1AGL sources (2 high-latitude and 6 on the galactic plane) were not detected in the final processing either because of low Observing Block (OB) exposure and/or due to their position in complex galactic regions. We report the results in a catalogue of all the detections obtained in each single OB, including the variability results for each of these sources. In particular, we found that 12 sources out of 42 or 11 out of 53 are variable, depending on the variability index used, where 42 and 53 are the number of sources for which these indices could be calculated. Seven of the 11 variable sources are blazars, the others are Crab pulsar+nebula, LS I +61 303, Cyg X-3, and 1AGLR J2021+4030.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/968
- Title:
- AGN automatic photometric classification
- Short Name:
- J/MNRAS/437/968
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we discuss an application of machine-learning-based methods to the identification of candidate active galactic nucleus (AGN) from optical survey data and to the automatic classification ofAGNs in broad classes. We applied four different machine-learning algorithms, namely the Multi Layer Perceptron, trained, respectively, with the Conjugate Gradient, the Scaled Conjugate Gradient, the Quasi Newton learning rules and the Support Vector Machines, Q4 to tackle the problem of the classification of emission line galaxies in different classes, mainly AGNs versus non-AGNs, obtained using optical photometry in place of the diagnostics based on line intensity ratios which are classically used in the literature. Using the same photometric features, we discuss also the behaviour of the classifiers on finer AGN classification tasks, namely Seyfert I versus Seyfert II, and Seyfert versus LINER. Furthermore, we describe the algorithms employed, the samples of spectroscopically classified galaxies used to train the algorithms, the procedure followed to select the photometric parameters and the performances of our methods in terms of multiple statistical indicators. The results of the experiments show that the application of self-adaptive data mining algorithms trained on spectroscopic data sets and applied to carefully chosen photometric parameters represents a viable alternative to the classical methods that employ time-consuming spectroscopic observations.
- ID:
- ivo://CDS.VizieR/J/ApJS/172/383
- Title:
- AGN candidates in the COSMOS field
- Short Name:
- J/ApJS/172/383
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic redshifts for the first 466 X-ray and radio-selected AGN targets in the 2deg^2^ COSMOS field. Spectra were obtained with the IMACS instrument on the Magellan (Baade) telescope, using the nod-and-shuffle technique. We identify a variety of type 1 and type 2 AGNs, as well as red galaxies with no emission lines. Our redshift yield is 72% down to i_AB_=24, although the yield is >90% for i_AB_<22. We expect the completeness to increase as the survey continues. When our survey is complete and additional redshifts from the zCOSMOS project are included, we anticipate ~1100 AGNs with redshifts over the entire COSMOS field. Our redshift survey is consistent with an obscured AGN population that peaks at z~0.7, although further work is necessary to disentangle the selection effects.
- ID:
- ivo://CDS.VizieR/J/AJ/133/313
- Title:
- AGN from RASS and SDSS DR5
- Short Name:
- J/AJ/133/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe further results of a program aimed at yielding ~104 fully characterized optical identifications of ROSAT X-ray sources. Our program employs X-ray data from the ROSAT All Sky Survey (RASS) and both optical imaging and spectroscopic data from the Sloan Digital Sky Survey (SDSS). RASS/SDSS data from 5740deg^2^ of sky spectroscopically covered in SDSS Data Release 5 provide an expanded catalog of 7000 confirmed quasars and other active galactic nuclei (AGNs) that are probable RASS identifications. Again, in our expanded catalog the identifications as X-ray sources are statistically secure, with only a few percent of the SDSS AGNs likely to be randomly superposed on unrelated RASS X-ray sources.
- ID:
- ivo://CDS.VizieR/J/A+AS/110/469
- Title:
- AGN from the RASS
- Short Name:
- J/A+AS/110/469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents long slit CCD spectroscopy and X-ray data of 283 AGN detected in the ROSAT-All Sky Survey (RASS). Basis of the sample is the pre-identification of 4651 RASS sources on 134 sky fields (covering in total ~3500sq.deg.). The 283 presented AGN were selected from 1253 AGN candidates resulting from the pre-identification work.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/705
- Title:
- AGN host galaxy morphologies in COSMOS
- Short Name:
- J/ApJ/691/705
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Hubble Space Telescope/Advanced Camera for Surveys images and a photometric catalog of the Cosmic Evolution Survey (COSMOS) field to analyze morphologies of the host galaxies of ~400 active galactic nucleus (AGN) candidates at redshifts 0.3<z<1.0. We compare the AGN hosts with a sample of nonactive galaxies drawn from the COSMOS field to match the magnitude and redshift distribution of the AGN hosts. We perform two-dimensional surface brightness modeling with GALFIT to yield host galaxy and nuclear point source magnitudes. X-ray-selected AGN host galaxy morphologies span a substantial range that peaks between those of early-type, bulge-dominated and late-type, disk-dominated systems. We also measure the asymmetry and concentration of the host galaxies. Unaccounted for, the nuclear point source can significantly bias results of these measured structural parameters, so we subtract the best-fit point source component to obtain images of the underlying host galaxies. Our concentration measurements reinforce the findings of our two-dimensional morphology fits, placing X-ray AGN hosts between early- and late-type inactive galaxies. AGN host asymmetry distributions are consistent with those of control galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/753/104
- Title:
- AGN identifications from AKARI and Swift
- Short Name:
- J/ApJ/753/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine data from two all-sky surveys in order to study the connection between the infrared and hard X-ray (>10keV) properties for local active galactic nuclei (AGNs). The Swift Burst Alert Telescope all-sky survey provides an unbiased, flux-limited selection of hard X-ray-detected AGNs. Cross-correlating the 22 month hard X-ray survey (Tueller et al. 2010, Cat. J/ApJS/186/378) with the AKARI all-sky survey (AKARI/PSCs; Ishihara et al. 2010, Cat. II/297; Yamamura et al. 2010, Cat. II/298), we studied 158 AGNs detected by the AKARI instruments. We find a strong correlation for most AGNs between the infrared (9, 18, and 90{mu}m) and hard X-ray (14-195keV) luminosities, and quantify the correlation for various subsamples of AGNs. Partial correlation analysis confirms the intrinsic correlation after removing the redshift contribution. The correlation for radio galaxies has a slope and normalization identical to that for Seyfert 1 galaxies, implying similar hard X-ray/infrared emission processes in both. In contrast, Compton-thick (CT) sources show a large deficit in the hard X-ray band, because high gas column densities diminish even their hard X-ray luminosities. We propose two photometric diagnostics for source classification: one is an X-ray luminosity versus infrared color diagram, in which type 1 radio-loud AGNs are well isolated from the others in the sample. The other uses the X-ray versus infrared color as a useful redshift-independent indicator for identifying CT AGNs. Importantly, CT AGNs and starburst galaxies in composite systems can also be differentiated in this plane based upon their hard X-ray fluxes and dust temperatures. This diagram may be useful as a new indicator to classify objects in new and upcoming surveys such as WISE and NuSTAR.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/1602
- Title:
- AGN sample in the northern XMM-XXL field
- Short Name:
- J/MNRAS/459/1602
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we describe and publicly release a catalogue consisting of 8445 point-like X-ray sources detected in the XMM-XXL north survey. For the 2512 AGN which have reliable spectroscopy from SDSS-III/BOSS, we present the X-ray spectral fitting which has been computed with a Bayesian approach. We have also applied an X-ray spectral stacking method to different sub-samples, selected on the basis of the AGN physical properties (L_2-10keV_, z, M_BH_, {lambda}_Edd_ and N_H_). We confirm the well-known Iwasawa-Taniguchi effect in our luminosity-redshift sub-samples, and argue that such an effect is due to a decrease in the covering factor of a distant obscuring 'torus' with increasing X-ray luminosity. By comparing the distribution of the reflection fraction, the ratio of the normalization of the reflected component to the direct radiation, we find that the low-luminosity, low-redshift sub-sample had systematically higher reflection fraction values than the high-redshift, high-luminosity one. On the other hand, no significant difference is found between samples having similar luminosity but different redshift, suggesting that the structure of the torus does not evolve strongly with redshift. Contrary to previous works, we do not find evidence for an increasing photon index at high Eddington ratio. This may be an indication that the structure of the accretion disc changes as the Eddington ratio approaches unity. Comparing our X-ray spectral analysis results with the optical spectral classification, we find that ~20 per cent of optical type-1 AGN show an X-ray absorbing column density higher than 10^21.5^cm^-2^, and about 50 per cent of type-2 AGN have an X-ray absorbing column density less than 10^21.5^cm^-2^. We suggest that the excess X-ray absorption shown in the high-luminosity optical type-1 AGN can be due to small-scale dust-free gas within (or close to) the broad-line region, while in the low-luminosity ones it can be due to a clumpy torus with a large covering factor.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/21
- Title:
- AGNs detected by 60 month Swift/BAT survey
- Short Name:
- J/ApJ/749/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Surveys above 10 keV represent one of the best resources to provide an unbiased census of the population of active galactic nuclei (AGNs). We present the results of 60 months of observation of the hard X-ray sky with Swift/Burst Alert Telescope (BAT). In this time frame, BAT-detected (in the 15-55keV band) 720 sources in an all-sky survey of which 428 are associated with AGNs, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of ~2 larger over similarly complete sets of AGNs. Our sample contains (at least) 15 bona fide Compton-thick AGNs and 3 likely candidates. Compton-thick AGNs represent ~5% of AGN samples detected above 15keV. We use the BAT data set to refine the determination of the log N-log S of AGNs which is extremely important, now that NuSTAR prepares for launch, toward assessing the AGN contribution to the cosmic X-ray background. We show that the log N-log S of AGNs selected above 10 keV is now established to ~10% precision. We derive the luminosity function of Compton-thick AGNs and measure a space density of 7.9^+4.1^_-2.9_x10^-5^/Mpc3 for objects with a de-absorbed luminosity larger than 2x10^42^erg/s. As the BAT AGNs are all mostly local, they allow us to investigate the spatial distribution of AGNs in the nearby universe regardless of absorption. We find concentrations of AGNs that coincide spatially with the largest congregations of matter in the local (<=85Mpc) universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions.
- ID:
- ivo://CDS.VizieR/J/ApJS/221/12
- Title:
- AGNs in the MIR using AllWISE data
- Short Name:
- J/ApJS/221/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an all-sky sample of ~1.4 million active galactic nuclei (AGNs) meeting a two-color infrared photometric selection criteria for AGNs as applied to sources from the Wide-field Infrared Survey Explorer final catalog release (AllWISE). We assess the spatial distribution and optical properties of our sample and find that the results are consistent with expectations for AGNs. These sources have a mean density of ~38 AGNs per square degree on the sky, and their apparent magnitude distribution peaks at g~20, extending to objects as faint as g~26. We test the AGN selection criteria against a large sample of optically identified stars and determine the "leakage" (that is, the probability that a star detected in an optical survey will be misidentified as a quasi-stellar object (QSO) in our sample) rate to be <=4.0x10^-5^. We conclude that our sample contains almost no optically identified stars (<=0.041%), making this sample highly promising for future celestial reference frame work as it significantly increases the number of all-sky, compact extragalactic objects. We further compare our sample to catalogs of known AGNs/QSOs and find a completeness value of >~84% (that is, the probability of correctly identifying a known AGN/QSO is at least 84%) for AGNs brighter than a limiting magnitude of R<~19. Our sample includes approximately 1.1 million previously uncataloged AGNs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/488/1035
- Title:
- AGN UV luminosity function
- Short Name:
- J/MNRAS/488/1035
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present lists of more than 80000 mostly UV-optical colour-selected AGN from 12 data sets, homogenised with respect to the assumed cosmology, magnitude system, and bandpass correction (if possible). We also present the selection functions for each of the 12 data sets, similarly homogenised. The total sample spans redshifts from z=0 to 7.5. The paper presents a detailed description of the combined sample and determinations of the AGN UV luminosity function throughout this redshift range. The code for developing and analysing AGN luminosity functions is available on GitHub (https://github.com/gkulkarni/QLF). The inferred UV luminosity functions can also be used to derive the contribution of AGN to the cosmic UV background and its effect on the intergalactic medium (IGM). The GitHub repository also includes code for this. Here we also present the luminosity functions in redshift bins, luminosity function evolution models from the paper, the 912{AA} and 1450{AA} volume emissivity of AGN from z=0 to 15, and the hydrogen photoionization rate contribution by AGN in this redshift range.
- ID:
- ivo://CDS.VizieR/J/A+AS/112/347
- Title:
- A Homogeneous Bright QSO Survey
- Short Name:
- J/A+AS/112/347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first paper in a series aimed at defining a statistically significant sample of QSOs in the range 15<B<18.75 and 0.3<z<2.2. The selection is carried out using direct plates obtained at the ESO and UK Schmidt Telescopes, scanned with the COSMOS facility and searched for objects with an ultraviolet excess. Follow-up spectroscopy, carried out at ESO La Silla, is used to classify each candidate. In this initial paper, we describe the scientific objectives of the survey; the selection and observing techniques used. We present the first sample of 285 QSOs (M_B_<-23) in a 153 sq.deg area, covered by the six "deep" fields, intended to obtain significant statistics down B=~18.75 with unprecedented photometric accuracy. From this database, QSO counts are determined in the magnitude range 17<B<18.75.
- ID:
- ivo://jvo/isas/darts/akari/AKARI-IRC_Catalogue_AllSky_ASTFLUX_1.0
- Title:
- AKARI Asteroid Flux Catalogue Version 1
- Short Name:
- AKARI_ASTEROID_V1
- Date:
- 23 Aug 2022 05:22:33
- Publisher:
- JVO
- Description:
- The AKARI Asteroid Flux Catalog contains photometric data of 5201 asteroids observed with the Infrared Camera (IRC) on board the Japanese infrared astronomical satellite AKARI. The catalog objects comprise the near-Earth asteroids, the main belt asteroids, the Cybeles, the Hildas, and the Jovian Trojan asteroids. The observations were performed by the all-sky survey in 9 or 18 micron bands as well as the slow-scan observations in 9 or 18 micron bands, and the pointed observations in 4, 7, 11, 15, and/or 24 micron bands.