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- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/448/893
- Title:
- Photometry and lines of (z~0.2-1.0) galaxies
- Short Name:
- J/A+A/448/893
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectrophotometric properties of a sample of 141 emission-line galaxies at redshifts in the range 0.2<z<1.0 with a peak around 0.2<=z<=0.4. The analysis is based on medium resolution (Rs=500-600), optical spectra obtained at VLT and Keck. The targets are mostly "Canada-France Redshift Survey" (<VII/225>) emission-line galaxies, with the addition of field galaxies randomly selected behind lensing clusters. We complement this sample with galaxy spectra from the "Gemini Deep Deep Survey" (<J/AJ/127/2455>) public data release. We have computed absolute magnitudes of the galaxies and measured the line fluxes and equivalent widths of the main emission/absorption lines. The last two have been measured after careful subtraction of the fitted stellar continuum using the platefit software originally developed for the SDSS and adapted to our data. We present a careful comparison of this software with the results of manual measurements.
- ID:
- ivo://CDS.VizieR/J/A+A/424/79
- Title:
- Photometry and Metallicity in ABCG 209 galaxies
- Short Name:
- J/A+A/424/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the properties of galaxy populations in the rich Abell cluster ABCG 209 at redshift z~0.21, on the basis of spectral classification of 102 member galaxies. We take advantage of available structural parameters to study separately the properties of bulge-dominated and disk-dominated galaxies. The star formation histories of the cluster galaxy populations are investigated by using line strengths and the 4000{AA} break, through a comparison to stellar population synthesis models. The dynamical properties of different spectral classes are examined in order to infer the past merging history of ABCG 209. The cluster is characterized by the presence of two components: an old galaxy population, formed very early (z_f>~3.5), and a younger (z_f>~1.2) population of infalling galaxies. We find evidence of a merger with an infalling group of galaxies occurred 3.5-4.5Gyr ago. The correlation between the position of the young H_delta-strong galaxies and the X-ray flux shows that the hot intracluster medium triggered a starburst in this galaxy population ~3Gyr ago.
- ID:
- ivo://CDS.VizieR/J/AJ/150/31
- Title:
- Photometry and redshifts of galaxies in the UDF
- Short Name:
- J/AJ/150/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry and derived redshifts from up to eleven bandpasses for 9927 galaxies in the Hubble Ultra Deep field (UDF), covering an observed wavelength range from the near-ultraviolet (NUV) to the near-infrared (NIR) with Hubble Space Telescope observations. Our Wide Field Camera 3 (WFC3)/UV F225W, F275W, and F336W image mosaics from the ultra-violet UDF (UVUDF) imaging campaign are newly calibrated to correct for charge transfer inefficiency, and use new dark calibrations to minimize background gradients and pattern noise. Our NIR WFC3/IR image mosaics combine the imaging from the UDF09 and UDF12 campaigns with CANDELS data to provide NIR coverage for the entire UDF field of view. We use aperture-matched point-spread function corrected photometry to measure photometric redshifts in the UDF, sampling both the Lyman break and Balmer break of galaxies at z~0.8--3.4, and one of the breaks over the rest of the redshift range. Our comparison of these results with a compilation of robust spectroscopic redshifts shows an improvement in the galaxy photometric redshifts by a factor of two in scatter and a factor three in outlier fraction (OLF) over previous UDF catalogs. The inclusion of the new NUV data is responsible for a factor of two decrease in the OLF compared to redshifts determined from only the optical and NIR data, and improves the scatter at z<0.5 and at z>2. The panchromatic coverage of the UDF from the NUV through the NIR yields robust photometric redshifts of the UDF, with the lowest OLF available.
- ID:
- ivo://CDS.VizieR/J/AJ/131/2383
- Title:
- Photometry and spectroscopy in the HDF-S
- Short Name:
- J/AJ/131/2383
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a deep photometric (B- and R-band) catalog and an associated spectroscopic redshift survey conducted in the vicinity of the Hubble Deep Field-South. The spectroscopy yields 53 extragalactic redshifts in the range 0<z<1.4, substantially increasing the body of spectroscopic work in this field to over 200 objects. The targets are selected from deep Anglo-Australian Telescope prime-focus images complete to R<24, and the spectroscopy is 50% complete at R=23.
- ID:
- ivo://CDS.VizieR/J/ApJ/661/750
- Title:
- Photometry and spectroscopy of MS 1054-03 members
- Short Name:
- J/ApJ/661/750
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a magnitude-limited, spectroscopic survey of the X-ray-luminous galaxy cluster MS 1054-03, we isolate 153 cluster galaxies and measure MS 1054's redshift and velocity dispersion to be z=0.8307+/-0.0004 and {sigma}_z_=1156+/-82km/s. The absorption-line, post-starburst ("E+A"), and emission-line galaxies, respectively, make up 63%+/-7%, 15%+/-4%, and 23%+/-4% of the cluster population. With photometry from HST ACS, we find that the absorption-line members define an exceptionally tight red sequence over a span of ~3.5mag in i775: their intrinsic scatter in (V606-i775) color is only 0.048+/-0.008, corresponding to a (U-B)z scatter of 0.041.
- ID:
- ivo://CDS.VizieR/J/ApJS/198/1
- Title:
- Photometry catalogs for the Lockman Hole
- Short Name:
- J/ApJS/198/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present broadband photometry and photometric redshifts for 187611 sources located in ~0.5deg^2^ in the Lockman Hole area. The catalog includes 388 X-ray-detected sources identified with the very deep XMM-Newton observations available for an area of 0.2deg^2^. The source detection was performed on the Rc-, z'-, and B-band images and the available photometry is spanning from the far-ultraviolet to the mid-infrared, reaching in the best-case scenario 21 bands. Astrometry corrections and photometric cross-calibrations over the entire data set allowed the computation of accurate photometric redshifts. Special treatment is undertaken for the X-ray sources, the majority of which are active galactic nuclei (AGNs). For normal galaxies, comparing the photometric redshifts to the 253 available spectroscopic redshifts, we achieve an accuracy of {sigma}_{Delta}z/(1+z)_=0.036, with 12.6% outliers. For the X-ray-detected sources, compared to 115 spectroscopic redshifts, the accuracy is {sigma}_{Delta}z/(1+z)_=0.069, with 18.3% outliers, where the outliers are defined as sources with |z_phot_-z_spec_|>0.15x(1+z_spec_).
- ID:
- ivo://CDS.VizieR/J/A+A/488/1167
- Title:
- Photometry of bulges at intermediate z
- Short Name:
- J/A+A/488/1167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Analysis of bulges to redshifts of up to z=1 have provided ambiguous results as to whether bulges as a class are old structures akin to elliptical galaxies or younger products of the evolution of their host disks. We aim to define a sample of intermediate-z disk galaxies harbouring central bulges, and a complementary sample of disk galaxies without measurable bulges. We intend to provide colour profiles for both samples, as well as measurements of nuclear, disk, and global colours, which may be used to constrain the relative ages of bulges and disks. We select a diameter-limited sample of galaxies in images from the HST/WFPC2 (Wide-Field Planetary Camera 2 at the Hubble Space Telescope) Groth Strip survey, which is divided into two subsamples of higher and lower inclination to assess the role of dust in the measured quantities. Mergers are visually identified and excluded. We take special care to control the pollution by ellipticals. The bulge sample is defined with a criterion based on nuclear surface brightness excess over the inward extrapolation of the exponential law fitted to the outer regions of the galaxies. We extract colour profiles on the semi-minor axis least affected by dust in the disk, and measure nuclear colours at 0.85kpc from the centre over those profiles. Disk colours are measured on major axis profiles; global colours are obtained from 2.6" diameter apertures. Colour transformations and K-corrections are calculated using SEDs covering bands UBVIJK, from the GOYA photometric survey. We obtain a parent sample containing 248 galaxies with known redshifts, spectroscopic or photometric, spanning 0.1<z<1.2. The bulge subsample comprises 54 galaxies (21.8% of the total), while the subsample with no measureable bulges is 55.2% of the total (137 galaxies). The remainder (23%) is composed of mergers. We list nuclear, disk, and global colours (observed and rest-frame) and magnitudes (apparent and absolute), as well as galaxy colour gradients for the samples with and without bulges, and make them available in electronic format. We also provide images, colour maps, plots of spectral energy distributions, major-axis surface brightness profiles, and minor-axis colour profiles for both samples.
- ID:
- ivo://CDS.VizieR/J/ApJ/779/65
- Title:
- Photometry of LBGs, LAEs and GNBs at z~2.85
- Short Name:
- J/ApJ/779/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a survey for z~2.85 Lyman-continuum (LyC) emission in the HS1549+1933 field and place constraints on the amount of ionizing radiation escaping from star-forming galaxies. Using a custom narrowband filter (NB3420) tuned to wavelengths just below the Lyman limit at z>=2.82, we probe the LyC spectral region of 49 Lyman break galaxies (LBGs) and 91 Ly{alpha} emitters (LAEs) spectroscopically confirmed at z>=2.82. Four LBGs and seven LAEs are detected in NB3420. Using V-band data probing the rest-frame nonionizing UV, we observe that many NB3420-detected galaxies exhibit spatial offsets between their LyC and nonionizing UV emission and are characterized by extremely blue NB3420-V colors, corresponding to low ratios of nonionizing to ionizing radiation (F_UV_/F_LyC_) that are in tension with current stellar population synthesis models. We measure average values of (F_UV_/F_LyC_) for our LBG and LAE samples, correcting for foreground galaxy contamination and H I absorption in the intergalactic medium. We find (F_UV_/F_LyC_)_corr_^LBG^=82+/-45 and (F_UV_/F_LyC_)_corr_^LAE^=7.4+/-3.6. These flux density ratios correspond, respectively, to relative LyC escape fractions of f_esc,rel_^LBG^=5%-8%, and f_esc,rel_^LAE^=18%-49% absolute LyC escape fractions of f_esc,rel_^LBG^=1%-2% and f_esc,rel_^LAE^=5%-15%, and a comoving LyC emissivity from star-forming galaxies of 8.8-15.0x10^24^ erg/s/Hz/Mpc^3^. In order to study the differential properties of galaxies with and without LyC detections, we analyze narrowband Ly{alpha} imaging and rest-frame near-infrared imaging, finding that while LAEs with LyC detections have lower Ly{alpha} equivalent widths on average, there is no substantial difference in the rest-frame near-infrared colors of LBGs or LAEs with and without LyC detections. These preliminary results are consistent with an orientation-dependent model where LyC emission escapes through cleared paths in a patchy interstellar medium.
