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941. Large-amplitude variables in Gaia DR2
ID:
ivo://CDS.VizieR/J/A+A/648/A44
Title:
Large-amplitude variables in Gaia DR2
Short Name:
J/A+A/648/A44
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photometric variability is an essential feature that sheds light on the intrinsic properties of celestial variable sources, the more so when photometry is available in various bands. In this respect, the all-sky Gaia mission is particularly attractive as it collects, among other quantities, epoch photometry measured quasi-simultaneously in three optical bands for sources ranging from a few magnitudes to fainter than magnitude twenty. The second data release (DR2) of the mission provides mean G, GBP and GRP photometry for 1.4 billion sources, but light curves and variability properties are available for only 0.5 million of them. Here, we provide a census of large-amplitude variables (LAVs) with amplitudes larger than 0.2mag in the G band for objects with mean brightnesses between 5.5 and 19mag. To achieve this, we rely on variability amplitude proxies in G, GBP and GRP computed from the uncertainties on the magnitudes published in DR2. We then apply successive filters to identify two subsets containing respectively sources with reliable mean GBP and GRP (for studies using colours) and sources having compatible amplitude proxies in G, GBP and GRP (for multi-band variability studies). The full catalogue gathers 23315874 LAV candidates, and the two subsets with increased levels of purity contain respectively 1148861 and 618966 sources. A multi-band variability analysis of the catalogue shows that different types of variable stars can be categorized according to their colour and blue-to-red amplitude ratios as determined from the G, GBP and GRP amplitude proxies. More specifically, four groups are globally identified. They mostly include long-period variables in a first group with amplitudes more than twice larger in the blue than in the red, hot compact variables in a second group with amplitudes smaller in the blue than in the red, classical instability strip pulsators in a third group with amplitudes larger in the blue than in the red by 50% to 80%, and other non-pulsating variables in a fourth group, mainly achromatic, but with still 10% of them having 20% to 50% larger amplitudes in the blue than in the red. The catalogue constitutes the first census of Gaia large amplitude variable (LAV) candidates, extracted from the public DR2 archive. The overview presented here illustrates the added-value of the mission for multi-band variability studies even at this stage when epoch photometry is not yet available for all sources.
942. Large area KX quasar catalogue
ID:
ivo://CDS.VizieR/J/MNRAS/424/2876
Title:
Large area KX quasar catalogue
Short Name:
J/MNRAS/424/2876
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of a large area, ~600deg^2^, K-band flux-limited spectroscopic survey for luminous quasars are presented. The survey utilizes the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) in regions of sky within the Sloan Digital Sky Survey (SDSS) footprint. The K-band excess (KX) of all quasars with respect to Galactic stars is exploited in combination with a photometric redshift/classification scheme to identify quasar candidates for spectroscopic follow-up observations. The data contained within this investigation will be able to provide new constraints on the fraction of luminous quasars reddened by dust with E(B-V)<=0.5mag. The spectroscopic sample is defined using the K-band, 14.0<=K<=16.6, and SDSS i-band limits of i=19.5, 19.7 and 22.0 over sky areas of 287, 150 and 196deg^2^, respectively. The survey includes >3200 known quasars from the SDSS and more than 250 additional confirmed quasars from the KX selection. A well-defined subsample of quasars in the redshift interval 1.0<=z<=3.5 includes 1152 objects from the SDSS and 172 additional KX-selected quasars. The quasar selection is >95 per cent complete with respect to known SDSS quasars and >95 per cent efficient, largely independent of redshift and i-band magnitude. The properties of the new KX-selected quasars confirm the known redshift-dependent effectiveness of the SDSS quasar selection and provide a sample of luminous quasars experiencing intermediate levels of extinction by dust. The catalogue represents an important step towards the assembly of a well-defined sample of luminous quasars that may be used to investigate the properties of quasars experiencing intermediate levels of dust extinction within their host galaxies or due intervening absorption line systems.
943. Large Bright Quasar Survey emission lines
ID:
ivo://CDS.VizieR/J/ApJS/134/35
Title:
Large Bright Quasar Survey emission lines
Short Name:
J/ApJS/134/35
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present measurements of the optical/UV emission lines for a large homogeneous sample of 993 quasars from the Large Bright Quasar Survey. Our largely automated technique accounts for continuum breaks and galactic reddening, and we perform multicomponent fits to emission line profiles, including the effects of blended iron emission, and of absorption lines both galactic and intrinsic. Here we describe the fitting algorithm and present the results of line fits to the LBQS sample, including upper limits to line equivalent widths when warranted. The distribution of measured line parameters, principally W_{lambda}_ and FWHM, are detailed for a variety of lines, including upper limits. We thus initiate a large-scale investigation of correlations between the high-energy continuum and emission lines in quasars, to be extended to complementary samples using similar techniques. High-quality, reproducible measurements of emission lines for uniformly selected samples will advance our understanding of active galaxies, especially in a new era of large surveys selected by a variety of complementary methods.
944. Large Bright Quasar Survey (LBQS) VII
ID:
ivo://CDS.VizieR/J/AJ/122/518
Title:
Large Bright Quasar Survey (LBQS) VII
Short Name:
J/AJ/122/518
Date:
21 Oct 2021
Publisher:
CDS
Description:
The source catalog for the Large Bright Quasar Survey (LBQS) and the FIRST Survey are compared in their regions of overlap to assess the efficiency of the LBQS selection algorithms. In the 270 deg^2^ common to both surveys, the LBQS contains ~100,000 stellar and ~40,000 nonstellar objects, while the FIRST catalog contains ~25,000 sources. Cross-correlation of these lists yields 67 positional coincidences between known LBQS quasars and FIRST sources and an additional 19 stellar and 149 nonstellar positional coincidences with the radio catalog. Spectroscopy of all the stellar matches and two-thirds of the nonstellar matches using the Keck I Telescope and the 6.5 m MMT produces eight new quasars. One BL Lac object, previously misclassified during the LBQS survey is also identified. The straightforward fractional incompleteness of the LBQS determined from this sample is 13%+/-4%, in good agreement with the published estimate of 10%.
945. LARGESS survey
ID:
ivo://CDS.VizieR/J/MNRAS/464/1306
Title:
LARGESS survey
Short Name:
J/MNRAS/464/1306
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the Large Area Radio Galaxy Evolution Spectroscopic Survey (LARGESS), a spectroscopic catalogue of radio sources designed to include the full range of radio AGN populations out to redshift z~0.8. The catalogue covers ~800deg^2^ of sky, and provides optical identifications for 19179 radio sources from the 1.4GHz Faint Images of the Radio Sky at Twenty-cm (FIRST) survey down to an optical magnitude limit of i_mod_<20.5 in Sloan Digital Sky Survey (SDSS) images. Both galaxies and point-like objects are included, and no colour cuts are applied. In collaboration with the WiggleZ and Galaxy And Mass Assembly (GAMA) spectroscopic survey teams, we have obtained new spectra for over 5000 objects in the LARGESS sample. Combining these new spectra with data from earlier surveys provides spectroscopic data for 12329 radio sources in the survey area, of which 10 856 have reliable redshifts. 85 per cent of the LARGESS spectroscopic sample are radio AGN (median redshift z=0.44), and 15 per cent are nearby star-forming galaxies (median z=0.08). Low-excitation radio galaxies (LERGs) comprise the majority (83 per cent) of LARGESS radio AGN at z<0.8, with 12 per cent being high-excitation radio galaxies (HERGs) and 5 per cent radio-loud QSOs. Unlike the more homogeneous LERG and QSO sub-populations, HERGs are a heterogeneous class of objects with relatively blue optical colours and a wide dispersion in mid-infrared colours. This is consistent with a picture in which most HERGs are hosted by galaxies with recent or ongoing star formation as well as a classical accretion disc.
946. Las Campanas Infrared Survey
ID:
ivo://CDS.VizieR/VII/228
Title:
Las Campanas Infrared Survey
Short Name:
VII/228
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Las Campanas Infrared Survey, based on broadband optical and near-infrared photometry, is designed to robustly identify a statistically significant and representative sample of evolved galaxies at redshifts z>1. We have completed an H-band imaging survey over 1.1{deg}^2^ of sky in six separate fields. The average 5{sigma} detection limit in a 4" diameter aperture is H~20.8. Here we describe the design of the survey, the observation strategies, data-reduction techniques, and object identification procedures. We present sample near-infrared and optical photometric catalogs for objects identified in two survey fields. The optical images of the Hubble Deep Field-South region obtained from the literature reach 5{sigma} detection thresholds in a 4" diameter aperture of U~24.6, B~26.1, V~25.6, R~25.1, and I~24.2mag. The optical images of the Chandra Deep Field-South region obtained from our own observations reach 5 {sigma} detection thresholds in a 4" diameter aperture of V~26.8, R~26.2, I~25.3, and z'~23.7mag. We perform object detection in all bandpasses and identify>~54000 galaxies over 1408 arcmin^2^ of sky in the two fields. Of these galaxies, ~14000 are detected in the H band and ~2000 have the colors of evolved galaxies, I-H >~3, at z>~1.
947. Las Campanas Infrared Survey. V.
ID:
ivo://CDS.VizieR/J/MNRAS/361/525
Title:
Las Campanas Infrared Survey. V.
Short Name:
J/MNRAS/361/525
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep Keck spectroscopy, using the Deep Imaging Multi-Object Spectrograph and the Low-Resolution Imaging Spectrometer spectrographs, of a large and representative sample of 67 extremely red objects (EROs) to H=20.5 in three fields (SSA22, Chandra Deep Field South and NTT Deep Field) drawn from the Las Campanas Infrared Survey (LCIRS). Using the colour cut (I-H)>3.0 (Vega magnitudes) adopted in earlier papers in this series, we verify the efficiency of this selection for locating and studying distant old sources. Spectroscopic redshifts are determined for 44 sources, of which only two are contaminating low-mass stars. When allowance is made for incompleteness, the spectroscopic redshift distribution closely matches that predicted earlier on the basis of photometric data.
948. LCs of 4 superluminous SNe from the ZTF survey
ID:
ivo://CDS.VizieR/J/ApJ/901/61
Title:
LCs of 4 superluminous SNe from the ZTF survey
Short Name:
J/ApJ/901/61
Date:
17 Feb 2022 13:56:34
Publisher:
CDS
Description:
We present photometry and spectroscopy of four hydrogen-poor luminous supernovae discovered during the 2-month long science commissioning and early operations of the Zwicky Transient Facility (ZTF) survey. Three of these objects, SN 2018bym (ZTF18aapgrxo), SN 2018avk (ZTF18aaisyyp), and SN 2018bgv (ZTF18aavrmcg), resemble typical SLSN-I spectroscopically, while SN 2018don (ZTF18aajqcue) may be an object similar to SN 2007bi experiencing considerable host galaxy reddening, or an intrinsically long-lived, luminous, and red SN Ic. We analyze the light curves, spectra, and host galaxy properties of these four objects and put them in context of the population of SLSN-I. SN 2018bgv stands out as the fastest-rising SLSN-I observed to date, with a rest-frame g-band rise time of just 10 days from explosion to peak-if it is powered by magnetar spin-down, the implied ejecta mass is only ~1M_{sun}_. SN 2018don also displays unusual properties-in addition to its red colors and comparatively massive host galaxy, the light curve undergoes some of the strongest light-curve undulations postpeak seen in an SLSN-I, which we speculate may be due to interaction with circumstellar material. We discuss the promises and challenges of finding SLSNe in large-scale surveys like ZTF given the observed diversity in the population.
949. LEGA-C DR2: galaxies in the COSMOS field
ID:
ivo://CDS.VizieR/J/ApJS/239/27
Title:
LEGA-C DR2: galaxies in the COSMOS field
Short Name:
J/ApJS/239/27
Date:
01 Mar 2022
Publisher:
CDS
Description:
We present the second data release of the Large Early Galaxy Astrophysics Census (LEGA-C), an ESO 130-night public spectroscopic survey conducted with VIMOS on the Very Large Telescope. We release 1988 spectra with typical continuum S/N~20{AA}^-1^ of galaxies at 0.6<~z<~1.0, each observed for ~20hr and fully reduced with a custom-built pipeline. We also release a catalog with spectroscopic redshifts, emission-line fluxes, Lick/IDS indices, and observed stellar and gas velocity dispersions that are spatially integrated quantities, including both rotational motions and genuine dispersion. To illustrate the new parameter space in the intermediate-redshift regime probed by LEGA-C, we explore relationships between dynamical and stellar population properties. The star-forming galaxies typically have observed stellar velocity dispersions of ~150km/s and strong H{delta} absorption (H{delta}_A_~5{AA}), while passive galaxies have higher observed stellar velocity dispersions (~200km/s) and weak H{delta} absorption (H{delta}_A_~0{AA}). Strong [OIII]5007/H{beta} ratios tend to occur mostly for galaxies with weak H{delta}_A_ or galaxies with higher observed velocity dispersion. Beyond these broad trends, we find a diversity of possible combinations of rest-frame colors, absorption-line strengths, and emission-line detections, illustrating the utility of spectroscopic measurements to more accurately understand galaxy evolution.
950. Leiden/Argentine/Bonn (LAB) Survey of Galactic HI
ID:
ivo://CDS.VizieR/VIII/76
Title:
Leiden/Argentine/Bonn (LAB) Survey of Galactic HI
Short Name:
VIII/76
Date:
21 Oct 2021
Publisher:
CDS
Description:
The LAB survey contains the final data release of observations of 21-cm emission from Galactic neutral hydrogen over the entire sky, merging the Leiden/Dwingeloo Survey (LDS: Hartmann & Burton 1997, Cat. VIII/54) of the sky north of -30{deg} with the Instituto Argentino de Radioastronomia Survey (IAR: Arnal et al. 2000A&AS..142...35A and Bajaja et al. 2005, Cat. VIII/75) of the sky south of -25{deg}. The angular resolution of the combined material is HPBW ~ 0.6{deg}. The LSR velocity coverage spans the interval -450 km/s to +400 km/s, at a resolution of 1.3km/s. The data were corrected for stray radiation at the Institute for Radioastronomy of the University of Bonn, refining the original correction applied to the LDS. The rms brightness-temperature noise of the merged database is 0.07-0.09 K. Residual errors in the profile wings due to defects in the correction for stray radiation are for most of the data below a level of 20-40 mK. It would be necessary to construct a telescope with a main beam efficiency of {eta}MB>99% to achieve the same accuracy. The merged and refined material entering the LAB Survey of Galactic H I is intended to be a general resource useful to a wide range of studies of the physical and structural characteristices of the Galactic interstellar environment. The LAB Survey is the most sensitive Milky Way H I survey to date, with the most extensive coverage both spatially and kinematically. The Survey is available as 3-D maps, with or without Hanning smoothing, covering the whole +/-458km/s or limited to +/-250km/s range. The resolution of the 3-D maps is 0.5{deg} in galactic longitude and latitude, and up to 1km/s in velocity. The survey exists also as (b,v) maps at longitude intervals stepped by 0.5{deg} -- these files supersedes the FITS files given in the Hartmann and Burton Atlas (Cat. VIII/54)