- ID:
- ivo://CDS.VizieR/J/ApJ/689/687
- Title:
- GOODS-N spectroscopic survey
- Short Name:
- J/ApJ/689/687
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a table of redshifts for 2907 galaxies and stars in the 145arcmin^2^ HST ACS GOODS-North, making this the most spectroscopically complete redshift sample obtained to date in a field of this size. We also include the redshifts, where available, in a table containing just under 7000 galaxies from the ACS area with K_s,AB_<24.5 measured from a deep K_s_ image obtained with WIRCam on the CFHT, as well as in a table containing 1016 sources with NUV_AB_<25 and 478 sources with FUV_AB_<25.5 (there is considerable overlap) measured from the deep GALEX images in the ACS area. Finally, we include the redshifts, where available, in a table containing the 1199 24um sources to 80uJy measured from the wider area Spitzer GOODS-North. The redshift identifications are greater than 90% complete to magnitudes of F435W_AB_=24.5, F850LP_AB_=23.3, and K_s,AB_=21.5, and to 24um fluxes of 250uJy. An extensive analysis of these data appear in a companion paper, but here we test the efficiency of color-selection techniques to identify populations of high-redshift galaxies and active galactic nuclei. We also examine the feasibility of doing tomography of the intergalactic medium with a 30m telescope.
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- ID:
- ivo://CDS.VizieR/J/ApJS/207/24
- Title:
- GOODS-S CANDELS multiwavelength catalog
- Short Name:
- J/ApJS/207/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a UV to mid-infrared multi-wavelength catalog in the CANDELS/GOODS-S field, combining the newly obtained CANDELS HST/WFC3 F105W, F125W, and F160W data with existing public data. The catalog is based on source detection in the WFC3 F160W band. The F160W mosaic includes the data from CANDELS deep and wide observations as well as previous ERS and HUDF09 programs. The mosaic reaches a 5{sigma} limiting depth (within an aperture of radius 0.17") of 27.4, 28.2, and 29.7 AB for CANDELS wide, deep, and HUDF regions, respectively. The catalog contains 34930 sources with the representative 50% completeness reaching 25.9, 26.6, and 28.1 AB in the F160W band for the three regions. In addition to WFC3 bands, the catalog also includes data from UV (U band from both CTIO/MOSAIC and VLT/VIMOS), optical (HST/ACS F435W, F606W, F775W, F814W, and F850LP), and infrared (HST/WFC3 F098M, VLT/ISAAC Ks, VLT/HAWK-I Ks, and Spitzer/IRAC 3.6, 4.5, 5.8, 8.0{mu}m) observations. The catalog is validated via stellar colors, comparison with other published catalogs, zero-point offsets determined from the best-fit templates of the spectral energy distribution of spectroscopically observed objects, and the accuracy of photometric redshifts. The catalog is able to detect unreddened star-forming (passive) galaxies with stellar mass of 10^10^M_{sun}_ at a 50% completeness level to z~3.4 (2.8), 4.6 (3.2), and 7.0 (4.2) in the three regions. As an example of application, the catalog is used to select both star-forming and passive galaxies at z~2-4 via the Balmer break. It is also used to study the color-magnitude diagram of galaxies at 0<z<4.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/599
- Title:
- H{alpha} and UV SFR in the local volume
- Short Name:
- J/ApJ/706/599
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a complete sample of ~300 star-forming galaxies within 11Mpc of the Milky Way, we evaluate the consistency between star formation rates (SFRs) inferred from the far ultraviolet (FUV) non-ionizing continuum and H{alpha} nebular emission, assuming standard conversion recipes in which the SFR scales linearly with luminosity at a given wavelength. Our analysis probes SFRs over 5 orders of magnitude, down to ultra-low activities on the order of ~10^-4^M_{sun}_/yr. The data are drawn from the 11Mpc H{alpha} and Ultraviolet Galaxy Survey (11HUGS), which has obtained H{alpha} fluxes from ground-based narrowband imaging, and UV fluxes from imaging with GALEX.
- ID:
- ivo://CDS.VizieR/J/MNRAS/416/2041
- Title:
- H{alpha} emitters at z=2.23
- Short Name:
- J/MNRAS/416/2041
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a narrow-band (H_2_S1, {lambda}_c_=2.121um, {delta}{lambda}=0.021um) imaging search with Wide Field Camera/United Kingdom Infrared Telescope for H{alpha} emitters (HAEs) around several potential signposts of rare (~10^-7^-10^-8^ comoving Mpc^-3^) overdense regions at z=2.23: an overdensity of quasi-stellar objects [QSOs; 2dF QSO Redshift Survey (2QZ) cluster], a powerful, high-redshift radio galaxy (HzRG) and a concentration of submillimetre galaxies (SMGs) and optically faint radio galaxies (OFRGs). In total, we detect 137 narrow-band emitter candidates down to emission-line fluxes of 0.5-1x10^-16^erg/s/cm^2^, across a total area of 0.56deg^2^ (2.1x10^5^ comoving Mpc^3^ at z=2.23) in these fields.
- ID:
- ivo://CDS.VizieR/J/ApJS/208/28
- Title:
- H{alpha} survey in the ONC
- Short Name:
- J/ApJS/208/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from an H{alpha} emission line survey in a 1 deg^2^ area centered on the Orion Nebula Cluster, obtained with the Wide Field Grism Spectrograph 2 on the 2.2 m telescope of the University of Hawaii. We identified 587 stars with H{alpha} emission, 99 of which, located mainly in the outer regions of the observed area, have not appeared in previous H{alpha} surveys. We determined the equivalent width (EW) of the line and, based on this, classified 372 stars as classical T Tauri stars (CTTSs) and 187 as weak-line T Tauri stars (WTTSs). Simultaneous r', i' photometry indicates a limiting magnitude of r' ~ 20 mag, but the sample is incomplete at r' > 17 mag. The surface distribution of the H{alpha} emission stars reveals a clustered population and a dispersed population, the former consisting of younger and more massive young stars than the latter. Comparison of the derived EWs with those found in the literature indicates variability of the H{alpha} line. We found that the typical amplitudes of the variability are not greater than a factor of two to three in most cases. We identified a subgroup of low-EW stars with infrared signatures indicative of optically thick accretion disks. We studied the correlations between the EW and other properties of the stars. Based on literature data, we examined several properties of our CTTS and WTTS subsamples and found significant differences in mid-infrared color indices, average rotational periods, and spectral energy distribution characteristics of the subsamples.
- ID:
- ivo://CDS.VizieR/J/ApJS/217/5
- Title:
- HAQ survey: red QSO candidates follow-up
- Short Name:
- J/ApJS/217/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Quasi-stellar objects (QSOs) whose spectral energy distributions (SEDs) are reddened by dust either in their host galaxies or in intervening absorber galaxies are to a large degree missed by optical color selection criteria like the ones used by the Sloan Digital Sky Survey (SDSS). To overcome this bias against red QSOs, we employ a combined optical and near-infrared (near-IR) color selection. In this paper, we present a spectroscopic follow-up campaign of a sample of red candidate QSOs which were selected from the SDSS and the UKIRT Infrared Deep Sky Survey (UKIDSS). The spectroscopic data and SDSS/UKIDSS photometry are supplemented by mid-infrared photometry from the Wide-field Infrared Survey Explorer. In our sample of 159 candidates, 154 (97%) are confirmed to be QSOs. We use a statistical algorithm to identify sightlines with plausible intervening absorption systems and identify nine such cases assuming dust in the absorber similar to Large Magellanic Cloud sightlines. We find absorption systems toward 30 QSOs, 2 of which are consistent with the best-fit absorber redshift from the statistical modeling. Furthermore, we observe a broad range in SED properties of the QSOs as probed by the rest-frame 2{mu}m flux. We find QSOs with a strong excess as well as QSOs with a large deficit at rest-frame 2{mu}m relative to a QSO template. Potential solutions to these discrepancies are discussed. Overall, our study demonstrates the high efficiency of the optical/near-IR selection of red QSOs.
- ID:
- ivo://CDS.VizieR/J/AJ/159/257
- Title:
- Hawaii IR parallax program. IV. L0-T8 BDs with UKIRT
- Short Name:
- J/AJ/159/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present parallaxes, proper motions, and J-band photometry for 348 L and T dwarfs measured using the wide-field near-infrared camera (WFCAM) on the United Kingdom Infrared Telescope (UKIRT). This is the largest single batch of infrared parallaxes for brown dwarfs to date. Our parallaxes have a median uncertainty of 3.5mas, similar to most previous ground-based infrared parallax surveys. Our target list was designed to complete a volume-limited parallax sample of L0-T8 dwarfs out to 25pc spanning declinations -30{deg} to +60{deg} (68% of the sky). We report the first parallaxes for 165 objects, and we improve on previous measurements for another 53 objects. Our targets include 104 objects (mostly early-L dwarfs) having Gaia DR2 parallax measurements with which our parallaxes are consistent. We include an extensive comparison of previous literature parallaxes for L and T dwarfs with both our results and Gaia DR2 measurements, identifying systematic offsets for some previous surveys. Our parallaxes confirm that 14 objects previously identified as wide common proper motion companions to main-sequence stars have distances consistent with companionship. We also report new J_MKO_ photometry for our targets, including the first measurements for 193 of our targets and improvements over previously published J_MKO_ photometry for another 60 targets. Altogether, our parallaxes will enable the first population studies using a volume-limited sample spanning spectral types L0-T8 defined entirely by parallaxes.
- ID:
- ivo://CDS.VizieR/J/AJ/127/3137
- Title:
- Hawaii redshifts in the ACS-GOODS region
- Short Name:
- J/AJ/127/3137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of an extensive spectroscopic survey of galaxies in the roughly 160 arcmin^2^ ACS-GOODS region surrounding the Hubble Deep Field North (HDF-N). We have identified 892 galaxies or stars with z<24, R<24.5, or B<25 in the region. The spectra were obtained with either the DEIMOS or LRIS spectrographs on the Keck 10m telescopes. The results are compared with photometric redshift estimates and with redshifts from the literature, as well as with the redshifts of a parallel effort led by a group at Keck. Our sample, when combined with the literature data, provides identifications for 1324 sources. We use our results to determine the redshift distributions with magnitude, to analyze the rest-frame color distributions with redshift and spectral type, and to investigate the dependence of the X-ray galaxy properties on the local galaxy density in the redshift interval z=0-1.5. We find the rather surprising result that the galaxy X-ray properties are not strongly dependent on the local galaxy density for galaxies in the same luminosity range.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A154
- Title:
- HDBSCAN star, galaxy, QSO classification
- Short Name:
- J/A+A/633/A154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Classification will be an important first step for upcoming surveys that will detect billions of new sources such as LSST and Euclid, as well as DESI, 4MOST and MOONS. The application of traditional methods of model fitting and colour-colour selections will face significant computational constraints, while machine-learning (ML) methods offer a viable approach to tackle datasets of that volume. While supervised learning methods can perform very well for classification tasks, the creation of representative and accurate training sets is a resource and time consuming task. We present a viable alternative using an unsupervised ML method to separate stars, galaxies and QSOs using photometric data. The heart of our work uses HDBSCAN to find the star, galaxy and QSO clusters in a multidimensional colour space. We optimized the hyperparameters and input attributes of three separate HDBSCAN runs, each to select a particular object class, and thus treat the output of each separate run as a binary classifier. We subsequently consolidate the output to give our final classifications, optimized on their F1 scores. We explore the use of Random Forest and PCA as part of the pre-processing stage for feature selection and dimensionality reduction. Using our dataset of ~50000 spectroscopically labelled objects we obtain an F1 score of 98.9, 98.9 and 93.13 respectively for star, galaxy and QSO selection using our unsupervised learning method. We find that careful attribute selection is a vital part of accurate classification with HDBSCAN. We applied our classification to a subset of the SDSS spectroscopic catalogue and demonstrate the potential of our approach in correcting misclassified spectra useful for DESI and 4MOST. Finally, we create a multiwavelength catalogue of 2.7 million sources using the KiDS, VIKING and ALLWISE surveys and publish corresponding classifications and photometric redshifts.
- ID:
- ivo://CDS.VizieR/J/ApJ/481/673
- Title:
- HDF flanking fields and related data
- Short Name:
- J/ApJ/481/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File flanking.dat contains Unpublished Catalogue of Galaxies identified by the DEEP Team in the Flanking Fields. This is the source catalogue that Vogt et al. (1997ApJ...479L.121V), Phillips et al. (1997ApJ...489..543P), Guzman et al. (1997ApJ...489..559G), and Mendez & Guzman (1998A&A...333..106M) used to select objects. The photometry in this catalogue was carried out using circular apertures of 3 arcsec diameter, as described by Phillips et al. (1997ApJ...489..543P). These will present small differences (~0.12mag, rms) relative to published values for the sample of 51 compact galaxies that were analysed by Phillips et al. (1997ApJ...489..543P) and Guzman et al. (1997ApJ...489..559G). This is because for the papers, the I(814) magnitudes were recalculated using elliptical apertures to 8 arcsec. The differences should only be significant in the case of galaxies with larger apparent sizes or with elongated shapes.