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2001. Photometric profiles from GOODS data
ID:
ivo://CDS.VizieR/J/ApJ/684/1026
Title:
Photometric profiles from GOODS data
Short Name:
J/ApJ/684/1026
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have conducted the largest systematic search so far for stellar disk truncations in disklike galaxies at intermediate redshift (z<1.1), using the Great Observatories Origins Deep Survey-South (GOODS-S) data from the Hubble Space Telescope ACS. Focusing on type II galaxies (i.e., downbending profiles), we explore whether the position of the break in the rest-frame B-band radial surface brightness profile (a direct estimator of the extent of the disk where most of the massive star formation is taking place) evolves with time. The number of galaxies under analysis (238 of a total of 505) is an order of magnitude larger than in previous studies. For the first time, we probe the evolution of the break radius for a given stellar mass (a parameter well suited to address evolutionary studies). We have explored the distribution of the scale lengths of the disks in the region inside the break and how this parameter relates to the break radius. We also present results of the statistical analysis of profiles of artificial galaxies, to assess the reliability of our results.
2002. Photometric quasar candidates in Stripe 82
ID:
ivo://CDS.VizieR/J/A+A/611/A97
Title:
Photometric quasar candidates in Stripe 82
Short Name:
J/A+A/611/A97
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have applied a convolutional neural network (CNN) to classify and detect quasars in the Sloan Digital Sky Survey Stripe 82 and also to predict the photometric redshifts of quasars. The network takes the variability of objects into account by converting light curves into images. The width of the images, noted w, corresponds to the five magnitudes ugriz and the height of the images, noted h, represents the date of the observation. The CNN provides good results since its precision is 0.988 for a recall of 0.90, compared to a precision of 0.985 for the same recall with a random forest classifier. Moreover 175 new quasar candidates are found with the CNN considering a fixed recall of 0.97. The combination of probabilities given by the CNN and the random forest makes good performance even better with a precision of 0.99 for a recall of 0.90. For the redshift predictions, the CNN presents excellent results which are higher than those obtained with a feature extraction step and different classifiers (a K-nearest-neighbors, a support vector machine, a random forest and a Gaussian process classifier). Indeed, the accuracy of the CNN within |{DELTA}z|<0.1 can reach 78.09%, within |{DELTA}z|<0.2 reaches 86.15%, within |{DELTA}z|<0.3 reaches 91.2% and the value of root mean square (rms) is 0.359. The performance of the KNN decreases for the three |{DELTA}z| regions, since within the accuracy of |{DELTA}z|<0.1, |{DELTA}z|<0.2, and |{DELTA}z|<0.3 is 73.72%, 82.46%, and 90.09% respectively, and the value of rms amounts to 0.395. So the CNN successfully reduces the dispersion and the catastrophic redshifts of quasars. This new method is very promising for the future of big databases such as the Large Synoptic Survey Telescope.
2003. Photometric redshifts in the EGOODS-North field
ID:
ivo://CDS.VizieR/J/ApJ/871/233
Title:
Photometric redshifts in the EGOODS-North field
Short Name:
J/ApJ/871/233
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep J- and H-band images in the extended Great Observatories Origins Deep Survey-North field covering an area of 0.22deg^2^. The observations were taken using WIRCam on the 3.6m Canada-France-Hawaii Telescope. Together with the reprocessed Ks-band image, the 5{sigma} limiting AB magnitudes (in 2" diameter apertures) are 24.7, 24.2, and 24.4 AB mag in the J, H, and Ks bands, respectively. We also release a multiband photometry and photometric redshift catalog containing 93598 sources. For non-X-ray sources, we obtained a photometric redshift accuracy {sigma}_NMAD_=0.036 with an outlier fraction {eta}=7.3%. For X-ray sources, which are mainly active galactic nuclei (AGNs), we cross-matched our catalog with the updated 2M-CDFN X-ray catalog from Xue+ (2016, J/ApJS/224/15) and found that 658 out of 683 X-ray sources have counterparts. GALEX UV data are included in the photometric redshift computation for the X-ray sources to give {sigma}_NMAD_=0.040 with {eta}=10.5%. Our approach yields more accurate photometric redshift estimates compared to previous works in this field. In particular, by adopting AGN-galaxy hybrid templates, our approach delivers photometric redshifts for the X-ray counterparts with fewer outliers compared to the 3D-Hubble Space Telescope catalog, which fit these sources with galaxy-only templates.
2004. Photometric redshifts in the Hawaii-HDF-N
ID:
ivo://CDS.VizieR/J/ApJS/215/27
Title:
Photometric redshifts in the Hawaii-HDF-N
Short Name:
J/ApJS/215/27
Date:
21 Oct 2021
Publisher:
CDS
Description:
We derive photometric redshifts (z_phot_) for sources in the entire (~0.4deg^2^) Hawaii-Hubble Deep Field-North (H-HDF-N) field with the EAzY code, based on point-spread-function-matched photometry of 15 broad bands from the ultraviolet (U band) to mid-infrared (IRAC 4.5{mu}m). Our catalog consists of a total of 131678 sources. We evaluate the z_phot_ quality by comparing z_phot_with spectroscopic redshifts (z_spec_) when available, and find a value of normalized median absolute deviation {sigma}_NMAD_=0.029 and an outlier fraction of 5.5% (outliers are defined as sources having |z_phot_-z_spec_|/(1+z_spec_)>0.15) for non-X-ray sources. More specifically, we obtain {sigma}_NMAD_=0.024 with 2.7% outliers for sources brighter than R=23mag, {sigma}_NMAD_=0.035 with 7.4% outliers for sources fainter than R=23mag, {sigma}_NMAD_=0.026 with 3.9% outliers for sources having z<1, and {sigma}_NMAD_=0.034 with 9.0% outliers for sources having z>1. Our z_phot_ quality shows an overall improvement over an earlier z_phot_ work that focused only on the central H-HDF-N area. We also classify each object as a star or galaxy through template spectral energy distribution fitting and complementary morphological parameterization, resulting in 4959 stars and 126719 galaxies. Furthermore, we match our catalog with the 2Ms Chandra Deep Field-North main X-ray catalog. For the 462 matched non-stellar X-ray sources (281 having z_spec_), we improve their z_phot_ quality by adding three additional active galactic nucleus templates, achieving {sigma}_NMAD_=0.035 and an outlier fraction of 12.5%.
2005. Photometric redshifts of the 2Ms CDF-S
ID:
ivo://CDS.VizieR/J/ApJS/187/560
Title:
Photometric redshifts of the 2Ms CDF-S
Short Name:
J/ApJS/187/560
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present reliable multiwavelength identifications and high-quality photometric redshifts for the 462 X-ray sources in the ~2Ms Chandra Deep Field-South (CDF-S) survey (Cat. J/ApJS/179/19). Source identifications are carried out using deep optical-to-radio multiwavelength catalogs, and are then combined to create lists of primary and secondary counterparts for the X-ray sources. We identified reliable counterparts for 442 (95.7%) of the X-ray sources, with an expected false-match probability of ~6.2%; we also selected four additional likely counterparts. The majority of the other 16 X-ray sources appear to be off-nuclear sources, sources associated with galaxy groups and clusters, high-redshift active galactic nuclei (AGNs), or spurious X-ray sources. A likelihood-ratio method is used for source matching, which effectively reduces the false-match probability at faint magnitudes compared to a simple error-circle matching method. We construct a master photometric catalog for the identified X-ray sources including up to 42 bands of UV-to-infrared data, and then calculate their photometric redshifts (photo-z's). The typical photo-z accuracy is ~6%-7%.
2006. Photometric search for transients in galaxy clusters
ID:
ivo://CDS.VizieR/J/AJ/135/1917
Title:
Photometric search for transients in galaxy clusters
Short Name:
J/AJ/135/1917
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have begun a program to search for supernovae and other transients in the fields of galaxy clusters with the 2.3m Bok Telescope on Kitt Peak. We present our automated photometric methods for data reduction, efficiency characterization, and initial spectroscopy. With this program, we aim to ultimately identify ~25-35 cluster Type Ia supernovae (SNe Ia) (~10 of which will be intracluster, hostless events) and constrain the SN Ia rate associated with old, passive stellar populations. With these measurements we will constrain the relative contribution of hostless and hosted SNe Ia to the metal enrichment of the intracluster medium.
2007. Photometric selection of quasars from SDSS. II.
ID:
ivo://CDS.VizieR/J/ApJS/180/67
Title:
Photometric selection of quasars from SDSS. II.
Short Name:
J/ApJS/180/67
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of 1172157 quasar candidates selected from the photometric imaging data of the Sloan Digital Sky Survey (SDSS). The objects are all point sources to a limiting magnitude of i=21.3 from 8417deg^2^ of imaging from SDSS Data Release 6 (DR6). This sample extends our previous catalog by using the latest SDSS public release data and probing both ultraviolet (UV)-excess and high-redshift quasars. While the addition of high-redshift candidates reduces the overall efficiency (quasars:quasar candidates) of the catalog to ~80%, it is expected to contain no fewer than 850000 bona fide quasars, which is ~8 times the number of our previous sample and ~10 times the size of the largest spectroscopic quasar catalog. Cross-matching between our photometric catalog and spectroscopic quasar catalogs from both the SDSS and 2dF survey yields 88879 spectroscopically confirmed quasars. For judicious selection of the most robust UV-excess sources (~500000 objects in all), the efficiency is nearly 97% -more than sufficient for detailed statistical analyses. The catalog's completeness to type 1 (broad-line) quasars is expected to be no worse than 70%, with most missing objects occurring at z<0.7 and 2.5<z<3.0. In addition to classification information, we provide photometric redshift estimates (typically good to {Delta}z+/-0.3[2{sigma}]) and cross-matching with radio, X-ray, and proper-motion catalogs. Finally, we consider the catalog's utility for determining the optical luminosity function of quasars and are able to confirm the flattening of the bright-end slope of the quasar luminosity function at z~4 as compared to z~2.
2008. Photometric & spectroscopic obs. of TOI-954 and K2-329
ID:
ivo://CDS.VizieR/J/AJ/161/82
Title:
Photometric & spectroscopic obs. of TOI-954 and K2-329
Short Name:
J/AJ/161/82
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of two short-period Saturn-mass planets, one transiting the G subgiant TOI-954 (TIC44792534, V=10.343, T=9.78) observed in TESS sectors 4 and 5 and one transiting the G dwarf K2-329 (EPIC246193072, V=12.70, K=10.67) observed in K2 campaigns 12 and 19. We confirm and characterize these two planets with a variety of ground-based archival and follow-up observations, including photometry, reconnaissance spectroscopy, precise radial velocity, and high-resolution imaging. Combining all available data, we find that TOI-954b has a radius of 0.852_-0.062_^+0.053^R_Jup_ and a mass of 0.174_-0.017_^+0.018^M_Jup_ and is in a 3.68day orbit, while K2-329b has a radius of 0.774_-0.024_^+0.026^R_Jup_ and a mass of 0.260_-0.022_^+0.020^M_Jup_ and is in a 12.46day orbit. As TOI-954b is 30 times more irradiated than K2-329b but more or less the same size, these two planets provide an opportunity to test whether irradiation leads to inflation of Saturn-mass planets and contribute to future comparative studies that explore Saturn-mass planets at contrasting points in their lifetimes.
2009. Photometric standards around gravitational lenses
ID:
ivo://CDS.VizieR/J/A+A/402/1157
Title:
Photometric standards around gravitational lenses
Short Name:
J/A+A/402/1157
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of secondary photometric standard stars in the neighborhood of 14 gravitationally lensed quasars. These stars were verified to be non variable using long-term monitoring. The instrumental magnitudes of the new standard stars have been transformed to the Johnson-Cousins BV(RI)c photometric system. For ten gravitational lenses (GLs) we also provide the BV(RI)c mean magnitudes of the integrated flux of all the lens components, for the epochs of the photometric calibration.
2010. Photometric Standard Stars
ID:
ivo://CDS.VizieR/II/50
Title:
Photometric Standard Stars
Short Name:
II/50
Date:
21 Oct 2021
Publisher:
CDS
Description:
The non-variable stars brighter than 5.0 mag in the equatorial zone between declinations +10{deg} and -10{deg} were adopted by IAU Commission 25 in 1970 as primary standards for the Johnson and Morgan UBV system of 1966. Fainter HR stars in the same zone were chosen as secondary standards. Data for the primary standards are taken from a Cape Royal Observatory Mimeogram and are presented in table2.dat. It gives the weighted mean V magnitudes and B-V colors based upon the best series available up to the end of 1966. The table is believed to provide a consistent UBV system over the southern sky. Most of the secondary standard star data, given in table4.dat, were published in Mon. Notes Astron. Soc. S. Afr. (22,23).