- ID:
- ivo://CDS.VizieR/J/ApJ/869/123
- Title:
- Keck Lyman continuum spectroscopic survey (KLCS)
- Short Name:
- J/ApJ/869/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a deep spectroscopic survey quantifying the statistics of the escape of ionizing radiation from star-forming galaxies at z~3. We measure the ratio of ionizing to non-ionizing UV flux density <f_900_/f_1500_>_obs_, where f_900_ is the mean flux density evaluated over the range [880,910]{AA}. We quantify the emergent ratio of ionizing to non-ionizing UV flux density by analyzing high signal-to-noise ratio composite spectra formed from subsamples with common observed properties and numbers sufficient to reduce the statistical uncertainty in the modeled IGM+CGM correction to obtain precise values of <f_900_/f_1500_>_out_, including a full-sample average <f_900_/f_1500>_out_=0.057{+/-}0.006. We show that <f_900_/f_1500_>_out_ increases monotonically with W_{lambda}_(Ly{alpha}), inducing an inverse correlation with UV luminosity as a by-product. We fit the composite spectra using stellar spectral synthesis together with models of the ISM in which a fraction f_c_ of the stellar continuum is covered by gas with column density N_HI_. We show that the composite spectra simultaneously constrain the intrinsic properties of the stars (L_900_/L_1500_)_int_ along with f_c_, N_HI_, E(B-V), and f_esc,abs_, the absolute escape fraction of ionizing photons. We find a sample-averaged f_esc,abs_=0.09{+/-}0.01, with subsamples falling along a linear relation <f_esc,abs_>~0.75[W_{lambda}_(Ly{alpha})/110{AA}]. Using the far-UV luminosity function, the distribution function n(W(Ly{alpha})), and the relationship between W_{lambda}_(Ly{alpha}) and <f_900_/f_1500_>_out_, we estimate the total ionizing emissivity of z~3 star-forming galaxies with M_uv_<=-19.5, which exceeds the contribution of quasi-stellar objects by a factor of ~3, and accounts for ~50% of the total {epsilon}LyC at z~3 estimated using indirect methods.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/624/A13
- Title:
- KiDS DR3 QSO catalog
- Short Name:
- J/A+A/624/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of quasars selected from broad-band photometric ugri data of the Kilo-Degree Survey Data Release 3 (KiDS DR3). The QSOs are identified by the random forest (RF) supervised machine learning model, trained on Sloan Digital Sky Survey (SDSS) DR14 spectroscopic data. We first cleaned the input KiDS data of entries with excessively noisy, missing or otherwise problematic measurements. Applying a feature importance analysis, we then tune the algorithm and identify in the KiDS multiband catalog the 17 most useful features for the classification, namely magnitudes, colors, magnitude ratios, and the stellarity index. We used the t-SNE algorithm to map the multidimensional photometric data onto 2D planes and compare the coverage of the training and inference sets. We limited the inference set to r<22 to avoid extrapolation beyond the feature space covered by training, as the SDSS spectroscopic sample is considerably shallower than KiDS. This gives 3.4 million objects in the final inference sample, from which the random forest identified 190,000 quasar candidates. Accuracy of 97% (percentage of correctly classified objects), purity of 91% (percentage of true quasars within the objects classified as such), and completeness of 87% (detection ratio of all true quasars), as derived from a test set extracted from SDSS and not used in the training, are confirmed by comparison with external spectroscopic and photometric QSO catalogs overlapping with the KiDS footprint. The robustness of our results is strengthened by number counts of the quasar candidates in the r band, as well as by their mid-infrared colors available from the Wide-field Infrared Survey Explorer (WISE). An analysis of parallaxes and proper motions of our QSO candidates found also in Gaia DR2 suggests that a probability cut of pQSO>0.8 is optimal for purity, whereas pQSO>0.7 is preferable for better completeness. Our study presents the first comprehensive quasar selection from deep high-quality KiDS data and will serve as the basis for versatile studies of the QSO population detected by this survey. We publicly release the resulting catalog at http://kids.strw.leidenuniv.nl/DR3/quasarcatalog.php, and the code at https://github.com/snakoneczny/kids-quasars
- ID:
- ivo://CDS.VizieR/J/AJ/162/224
- Title:
- King 7 Vilnius photometry. II. Extinctions
- Short Name:
- J/AJ/162/224
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- Interstellar extinction in two concentric square areas of the sizes 1.25x1.25deg^2^ and 0.2x0.2deg^2^ in the direction of open cluster King7 is investigated applying two-dimensional photometric classification of stars observed in the Vilnius seven-color photometric system down to V=15.5mag (1084 stars) and 19.5mag (584 stars), respectively. The cluster members (284 stars) are identified applying their coordinates, proper motions, and parallaxes taken from the Gaia EDR3 catalog. New parameters of the cluster (distance, diameter, interstellar extinction, and age) are obtained. Photogeometric distances of stars are taken from Bailer-Jones et al. (2021) based on the Gaia parallaxes from EDR3. Physically the cluster is located at the outer edge of the Perseus spiral arm at d=2.74kpc, its diameter is 9.6pc, the age is 175{+/-}25Myr, the earliest stars are of spectral classes B6-B7. The average interstellar extinction A_V_=4.24mag. From the radial velocities of CO and the Galactic rotation curve we estimate distances to the nearby dust clouds TGU H989 P2 and P3 at 650-670pc from the Sun.
- ID:
- ivo://CDS.VizieR/I/199A
- Title:
- Lick Northern Proper Motion Program: NPM1 Catalog
- Short Name:
- I/199A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The NPM1 catalog is the first part of the Lick Northern Proper Motion (NPM) program to measure absolute proper motions, on an inertial system defined by some 50,000 faint galaxies, for some 300,000 stars over a blue apparent magnitude range from 8 to 18. There are 1246 6-degree by 6-degree fields in the NPM survey (to declination -23 degrees). The NPM1 catalog covers the 72% of the northern sky lying outside the Milky Way and contains some 149,000 stars from measures in 899 of the 1246 NPM fields. A second catalog (NPM2) will cover the NPM Milky Way fields. The Yale Southern Proper Motion (SPM) program will complete the southern sky. Each NPM field was photographed at two epochs between 1947 and 1988. The mean first and second epochs are 1950 and 1977; the average epoch difference is 27 years. The first-epoch plates were taken in the blue only; both blue and yellow plates were taken at the second epoch. Some 94000 stars were chosen anonymously for the NPM astrometric reductions and for statistical studies of stellar motions. In addition, the NPM1 catalog contains some 28000 positional reference stars, and some 27000 stars were chosen from the Lick Input Catalog of Special Stars (ICSS). The previous version of the NPM1 Catalog (I/199) deposited with the data centers (ADC and CDS) gives positions for equinox B1950 and computed epoch 1950, and is in one data file (148,940 lines) concatenating the 114 one-degree declination zones from +90 degrees to -23 degrees. Each star has an NPM1 "name" reflecting the declination zone and a running number in right ascension order within the zone. The present J2000 version gives the NPM1 positions transformed into the J2000 system and updated to the epoch 2000 using the NPM1 proper motions. The proper motions have been rotated into the J2000 coordinate system. The J2000 NPM1 Catalog is ordered in zones from +90 degrees to -23 degrees, and within each zone, the stars are sorted in right ascension order. To avoid "renaming" stars, the B1950 NPM1 "names" were retained, but the user must note that these no longer strictly reflect the declination zone and right ascension order in the J2000 NPM1 Catalog. The J2000 NPM1 Catalog is also available as 114 separate files, one for each declination zone from +90 degrees (z+90j) to -23 degrees (z-23j), from http://www.ucolick.org/~npm/NPM1/zones/ Each star's entry includes the absolute proper motion and blue magnitude. For 97% of the stars the color is also given. Other data given for each star are: the original mean epoch, a stellar class code, the number of NPM fields measured, and discrepancy flags for position, proper motion, and photometry. Finally, as an additional identification, the AGK3 (north) or SAO (south) number (if any) is given. The rms errors of the NPM absolute proper motions are about 0.5"/cent in each coordinate. The rms position errors at the catalog epoch 1950 average about 0.15" in each coordinate. The rms errors for the NPM photographic photometry average about 0.2 mag in B, and 0.15 mag in B-V. More complete information is available in the PostScript documentation for the 1993 (B1950) NPM1 Catalog (npm1b.ps), written by R.B. Hanson. We thank the National Science Foundation for its continued support of the NPM program. Recent work was supported by NSF grant AST-9530632. Current work is supported by NSF grant AST-9988105.
- ID:
- ivo://CDS.VizieR/I/283A
- Title:
- Lick NPM2 Catalog
- Short Name:
- I/283A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The NPM2 Catalog is the second part of the Lick Northern Proper Motion (NPM) program to measure absolute proper motions, on an inertial system defined by distant galaxies, for nearly 400,000 stars over a blue apparent magnitude range from 8 to 18. There are 1246 6x6degree fields in the NPM survey (to declination -23 degrees). The NPM2 Catalog covers the 28% of the northern sky lying near the plane of the the Milky Way and contains some 232,000 stars in the 347 NPM fields remaining after the 1993 NPM1 Catalog (149,000 stars in 899 fields away from the Milky Way). Each NPM field was photographed with the 51cm Carnegie Double Astrograph at two epochs between 1947 and 1988. The mean first and second epochs are 1950 and 1977; the average epoch difference is 27 years. The first-epoch plates were taken in the blue only; both blue and yellow plates were taken at the second epoch. For NPM2, the plates were scanned by the Precision Measuring Machine (PMM) at the US Naval Observatory, Flagstaff. From the PMM scans, 120,000 faint (B>14) stars were chosen anonymously for the NPM astrometric reductions and for statistical studies of stellar motions. The NPM2 catalog also contains 92,000 bright (B<14) positional reference stars, mostly from the Tycho-2 Catalogue, and 35,000 stars chosen for astronomical interest from Klemola's "Lick Input Catalog of Special Stars". (These categories overlap). Details of the NPM2 star selection, data reductions, and catalog compilation will be presented in a paper being prepared for the Astronomical Journal. The completed version of the NPM2 Catalog totals 232,062 stars from all 347 NPM2 fields; it supersedes the September 2002 preliminary version (295 fields). Together with the NPM1 Catalog (Cat. I/199, or http://www.ucolick.org/~npm/NPM1/) the NPM2 Catalog completes the Lick Northern Proper Motion program after more than a half-century of work by three generations of Lick Observatory astronomers. The NPM2 catalog gives J2000 positions computed for the catalog epoch 2000, and is ordered in 108 one-degree declination zones from +83 degrees to -23 degrees. Following the convention of the NPM1 catalog, each NPM2 star has an NPM2 "name" (e.g. +83.0001) reflecting the declination zone and a running number in right ascension order within the zone. The NPM2 Catalog is also available as 108 separate files, one for each declination zone from +83 degrees (z+83n) to -23 degrees (z-23n), from http://www.ucolick.org/~npm/NPM2/zones/ Each star's entry includes the absolute proper motion and blue (B) magnitude. For 98.5% of the stars the B-V color is also given. Other data given for each star are: the original mean epoch, a stellar class code, the number of NPM fields on which the star was measured, and discrepancy flags for proper motion, and photometry. Tycho-2 numbers are given for the primary positional reference stars (40% of NPM2); for these stars the Tycho B,V photometry, transformed to Johnson B and B-V, has been averaged with the NPM2 photographic photometry, with appropriate weights. ACRS and Hipparcos numbers are also given for NPM2 stars selected from those catalogs. The RMS precision of the NPM2 individual proper motions is about 0.6"/cent (6mas/yr) in each coordinate, comparable to the NPM1 errors. The NPM2 relative proper motions in each field were reduced to absolute (ICRS system) using an average of 370 Tycho-2 stars per NPM2 field. Magnitude-dependent systematic errors for the brightest (8<B<12) NPM2 stars were removed in the same reductions. The RMS accuracy of the proper motion zero point in each field is about 0.05"/cent (0.5mas/yr) in each coordinate. The RMS position errors at the NPM2 catalog epoch 2000 average about 0.2" (200mas) in each coordinate, due mostly to the accumulated proper motion error from original plate epochs (average 1968) to 2000. The pure positional errors at the original epochs average 0.08" (80mas) in each coordinate. The RMS errors for the NPM photographic photometry average about 0.18mag in B, and 0.20 mag in B-V. We thank the National Science Foundation for its long-term support of the NPM program. The NPM2 phase was supported by NSF grants AST-9530632 and AST-9988105. We thank the Yale Southern Proper Motion group (W. van Altena, I. Platais, and T. Girard) for their help in developing software to process the PMM plate scans.
- ID:
- ivo://CDS.VizieR/J/ApJ/869/9
- Title:
- Machine-learning investigation of the open cluster M67
- Short Name:
- J/ApJ/869/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we use a machine-learning method, random forest (RF), to identify reliable members of the old (4Gyr) open cluster M67 based on the high-precision astrometry and photometry taken from the second Gaia data release (Gaia-DR2). The RF method is used to calculate membership probabilities of 71117 stars within 2.5{deg} of the cluster center in an 11-dimensional parameter space, the photometric data are also taken into account. Based on the RF membership probabilities, we obtain 1502 likely cluster members (>=0.6), 1361 of which are high-probability cluster members (>=0.8). Based on high-probability memberships with high-precision astrometric data, the mean parallax (distance) and proper-motion of the cluster are determined to be 1.1327+/-0.0018mas (883+/-1pc) and (<{mu}_{alpha}_cos{delta}>,<{mu}_{delta}_>)=(-10.9378+/-0.0078,-2.9465 +/-0.0074)mas/yr, respectively. We find the cluster to have a mean radial velocity of +34.06+/-0.09km/s, using 74 high-probability cluster members with precise radial-velocity measures. We investigate the spatial structure of the cluster, the core and limiting radius are determined to be 4.80'+/-0.11' (~1.23+/-0.03pc) and 61.98'+/-1.50' (~15.92+/-0.39pc), respectively. Our results reveal that an escaped member with high membership probability (~0.91) is located at a distance of 77' (~20pc) from the cluster center. Furthermore, our results reveal that at least 26.4% of the main-sequence stars in M67 are binary stars. We confirm that significant mass segregation has taken place within M67.
- ID:
- ivo://CDS.VizieR/II/38
- Title:
- Miniphote Catalogue
- Short Name:
- II/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/655/A47
- Title:
- MOOJa catalogs for Solar System Objects
- Short Name:
- J/A+A/655/A47
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The Javalambre Photometric Local Universe Survey (J-PLUS) is an observational campaign that aims to obtain photometry in 12 ultraviolet-visible filters (0.3-1um) over ~8500deg^2^ of the sky observable from Javalambre (Teruel, Spain). Due to its characteristics and observation strategy, this survey will allow a great number of Solar System small bodies to be analyzed, and with improved spectrophotometric resolution with respect to previous large-area photometric surveys in optical wavelengths. The main goal of the present work is to present the first catalog of magnitudes and colors of minor bodies of the Solar System compiled using the first data release (DR1) of the J-PLUS observational campaign: the Moving Objects Observed from Javalambre (MOOJa) catalog. Using the compiled photometric data we obtained very-low-resolution reflectance (photo)spectra of the asteroids. We first used a {sigma}-clipping algorithm in order to remove outliers and clean the data. We then devised a method to select the optimal solar colors in the J-PLUS photometric system. These solar colors were computed using two different approaches: on one hand, we used different spectra of the Sun convolved with the filter transmissions of the J-PLUS system, and on the other, we selected a group of solar-type stars in the J-PLUS DR1 according to their computed stellar parameters. Finally, we used the solar colors to obtain the reflectance spectra of the asteroids. We present photometric data in the J-PLUS filters for a total of 3122 minor bodies (3666 before outlier removal), and we discuss the main issues with the data, as well as some guidelines to solve them.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A111
- Title:
- Multi-color detection of gravitational arcs
- Short Name:
- J/A+A/567/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Strong gravitational lensing provides fundamental insights into the understanding of the dark matter distribution in massive galaxies, galaxy clusters and the background cosmology. Despite their importance, the number of gravitational arcs discovered so far is small. The urge for more complete, large samples and unbiased methods of selecting candidates is rising. A number of methods for the automatic detection of arcs have been proposed in the literature, but large amounts of spurious detections retrieved by these methods forces observers to visually inspect thousands of candidates per square degree in order to clean the samples. This approach is largely subjective and requires a huge amount of eye-ball checking, especially considering the actual and upcoming wide field surveys, which will cover thousands of square degrees. In this paper we study the statistical properties of colours of gravitational arcs detected in the 37deg^2^ of the CARS survey.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/842
- Title:
- New X-ray-selected SNRs detection with Chandra
- Short Name:
- J/ApJ/725/842
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a study of the supernova remnant (SNR) population in a sample of six nearby galaxies (NGC 2403, NGC 3077, NGC 4214, NGC 4449, NGC 4395, and NGC 5204) based on Chandra archival data. We have detected 244 discrete X-ray sources down to a limiting flux of 10^-15^ erg/s/cm^2^. We identify 37 X-ray-selected thermal SNRs based on their X-ray colors or spectra, 30 of which are new discoveries. In many cases, the X-ray classification is confirmed based on counterparts with SNRs identified in other wavelengths. Three of the galaxies in our sample (NGC 4214, NGC 4395, and NGC 5204) are studied for the first time, resulting in the discovery of 13 thermal SNRs. We discuss the properties (luminosity, temperature, and density) of the X-ray-detected SNRs in the galaxies of our sample in order to address their dependence on their environment. We find that X-ray-selected SNRs in irregular galaxies appear to be more luminous than those in spirals. We attribute this to the lower metallicities and therefore more massive progenitor stars of irregular galaxies or the higher local densities of the interstellar medium. We also discuss the X-ray-selected SNR populations in the context of the star formation rate of their host galaxies. A comparison of the numbers of observed luminous X-ray-selected SNRs with those expected based on the luminosity functions of X-ray SNRs in the Magellanic Clouds and M33 suggest different luminosity distributions between the SNRs in spiral and irregular galaxies with the latter tending to have flatter distributions.
