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17371. 1WHSP: VHE {gamma}-ray blazar candidates
ID:
ivo://CDS.VizieR/J/A+A/579/A34
Title:
1WHSP: VHE {gamma}-ray blazar candidates
Short Name:
J/A+A/579/A34
Date:
21 Oct 2021
Publisher:
CDS
Description:
Blazars are the dominant type of extragalactic sources at microwave and at {gamma}-ray energies. In the most energetic part of the electromagnetic spectrum (E>~100GeV) a high fraction of high Galactic latitude sources are blazars of the high synchrotron peaked (HSP) type, that is BL Lac objects with synchrotron power peaking in the UV or in the X-ray band. Building new large samples of HSP blazars is key to understand the properties of jets under extreme conditions, and to study the demographics and the peculiar cosmological evolution of these sources. High synchrotron peaked blazars are remarkably rare, with only a few hundreds of them expected to be above the sensitivity limits of currently available surveys, some of which include hundreds of millions of sources. To find these very uncommon objects, we have devised a method that combines ALLWISE survey data with multi-frequency selection criteria. The sample was defined starting from a primary list of infrared colour-colour selected sources from the ALLWISE all sky survey database, and applying further restrictions on IR-radio and IR-X-ray flux ratios. Using a polynomial fit to the multi-frequency data (radio to X-ray), we estimated synchrotron peak frequencies and fluxes of each object.
17372. Wide Angle ROSAT Pointed Survey, First Phase (WARPS-I)
ID:
ivo://nasa.heasarc/warps
Title:
Wide Angle ROSAT Pointed Survey, First Phase (WARPS-I)
Short Name:
ROSAT/WARPS
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
The Wide Angle ROSAT Pointed Survey, First Phase (WARPS-I) table is a catalog which contains optical identifications for objects found in a serendipitous survey of relatively deep, pointed ROSAT observations for clusters of galaxies. The X-ray source detection algorithm used by WARPS is Voronoi Tessellation and Percolation (VTP), a technique which is equally sensitive to point sources and to extended sources of low surface brightness. WARPS-I is based on the central regions of 86 ROSAT PSPC fields, covering an area of 16.2 square degrees. The X-ray source screening and optical identification process for WARPS-I yielded 34 clusters at 0.06<z<0.75. Twenty-two of these clusters form a complete, statistically well-defined sample drawn from 75 of these 86 fields, covering an area of 14.1 square degrees, with a flux limit of F(0.5-2.0keV) = 6.5x10<sup>-14</sup> erg/cm<sup>2</sup>/s. This sample can be used to study the properties and evolution of the gas, galaxy and dark matter content of clusters and to constrain cosmological parameters. This online catalog was created by the HEASARC in May 2003 based on machine-readable versions of tables 2, 3, 4 and 5 of Perlman et al. (2002) that were obtained from the CDS. This is a service provided by NASA HEASARC .
17373. Wide Angle ROSAT Pointed Survey, Second Phase (WARPS-II) Clusters Catalog
ID:
ivo://nasa.heasarc/warps2
Title:
Wide Angle ROSAT Pointed Survey, Second Phase (WARPS-II) Clusters Catalog
Short Name:
WARPS2
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the galaxy cluster catalog from the second, larger phase of the Wide Angle ROSAT Pointed Survey (WARPS), an X-ray selected survey for high-redshift galaxy clusters. WARPS is among the largest deep X-ray cluster surveys and is being used to study the properties and evolution of galaxy clusters. The WARPS-II sample contains 125 clusters serendipitously detected in a survey of 301 ROSAT PSPC pointed observations and covers a sky area of 56.7 deg<sup>2</sup>. Of these 125 clusters, 53 have not been previously reported in the literature. The authors have nearly complete spectroscopic follow-up of the clusters, which range in redshift from z = 0.029 to z = 0.92 with a median redshift of z = 0.29 and they find 59 clusters with z >= 0.3 (29 not previously reported in the literature) and 11 clusters with z >= 0.6 (6 not previously reported). They also define a statistically complete subsample of 102 clusters above a uniform flux limit of 6.5 x 10<sup>-14</sup> ergs/cm<sup>2</sup>/s (0.5 - 2.0 keV). In their paper, the authors also compare their redshifts, fluxes, and detection methods to other similar published cluster surveys and state that they find no serious issues with their measurements or completeness. The list of ROSAT pointings used in WARPS-II is given in Table 1 of the first reference paper. The WARPS-I cluster catalog (the second reference listed below) is also available in Browse as the WARPS table. This table was created by the HEASARC in September 2010 based on the combination of the electronic versions of Tables 2, 3, and 4 from the first reference paper which were obtained from the CDS (their catalog J/ApJS/176/374). This is a service provided by NASA HEASARC .
17374. Wide-Angle-Tailed radio galaxies redshifts
ID:
ivo://CDS.VizieR/J/AJ/120/2269
Title:
Wide-Angle-Tailed radio galaxies redshifts
Short Name:
J/AJ/120/2269
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new redshifts and positions for 635 galaxies in nine rich clusters containing wide-angle tailed (WAT) radio galaxies. Combined with existing data, we now have a sample of 18 WAT-containing clusters with more than 10 redshifts. This sample contains a substantial portion of the WAT clusters in the VLA 20 cm survey of Abell clusters, including 75% of WAT clusters in the complete survey (z<=0.09), and 20% of WAT clusters with z>0.09. It is a representative sample, which should not contain biases other than selection by radio morphology. We graphically present the new data using histograms and sky maps. A semiautomated procedure is used to search for emission lines in the spectra in order to add and verify galaxy redshifts. We find that the average apparent fraction of emission-line galaxies is about 9% in both the clusters and the field. We investigate the magnitude completeness of our redshift surveys with CCD data for a test case, Abell 690. This case indicates that our galaxy target lists are deeper than the detection limit of a typical MX exposure, and they are 82% complete down to R=19.0. The importance of the uniformity of the placement of fibers on targets is posited, and we evaluate this in our data sets. We find some cases of nonuniformities which may influence dynamical analyses. A second paper will use this database to look for correlations between the WAT radio morphology and the cluster's dynamical state.
17375. Wide binaries in Taurus and Upper Sco
ID:
ivo://CDS.VizieR/J/ApJ/703/1511
Title:
Wide binaries in Taurus and Upper Sco
Short Name:
J/ApJ/703/1511
Date:
21 Oct 2021
Publisher:
CDS
Description:
We describe an astrometric and spectroscopic campaign to confirm the youth and association of a complete sample of candidate wide companions in Taurus and Upper Sco. Our survey found 15 new binary systems (three in Taurus and 12 in Upper Sco) with separations of 3"-30" (500-5000AU) among all of the known members with masses of 2.5-0.012M_{sun}_. The total sample of 49 wide systems in these two regions conforms to only some expectations from field multiplicity surveys. Higher mass stars have a higher frequency of wide binary companions, and there is a marked paucity of wide binary systems near the substellar regime. However, the separation distribution appears to be log-flat, rather than declining as in the field, and the mass ratio distribution is more biased toward similar-mass companions than the initial mass function or the field G-dwarf distribution. The maximum separation also shows no evidence of a limit at <~5000AU until the abrupt cessation of any wide binary formation at system masses of ~0.3M_{sun}_. We attribute this result to the post-natal dynamical sculpting that occurs for most field systems; our binary systems will escape to the field intact, but most field stars are formed in denser clusters and undergo significant dynamical evolution. In summary, only wide binary systems with total masses <~0.3M_{sun}_ appear to be "unusually wide."
17376. Wide binaries in Tycho-Gaia: search method
ID:
ivo://CDS.VizieR/J/MNRAS/472/675
Title:
Wide binaries in Tycho-Gaia: search method
Short Name:
J/MNRAS/472/675
Date:
21 Oct 2021
Publisher:
CDS
Description:
We mine the Tycho-Gaia astrometric solution (TGAS) catalogue for wide stellar binaries by matching positions, proper motions and astrometric parallaxes. We separate genuine binaries from unassociated stellar pairs through a Bayesian formulation that includes correlated uncertainties in the proper motions and parallaxes. Rather than relying on assumptions about the structure of the Galaxy, we calculate Bayesian priors and likelihoods based on the nature of Keplerian orbits and the TGAS catalogue itself. We calibrate our method using radial velocity measurements and obtain 7108 high-confidence candidate wide binaries with projected separations s<~1pc. The normalization of this distribution suggests that at least 0.7 per cent of TGAS stars have an associated, distant TGAS companion in a wide binary. We demonstrate that Gaia's astrometry is precise enough that it can detect projected orbital velocities in wide binaries with orbital periods as large as 10^6^yr. For pairs with s<~4x10^4^au, characterization of random alignments indicates our contamination to be 5-10 per cent. For s<~5x10^3^au, our distribution is consistent with Opik's law. At larger separations, the distribution is steeper and consistent with a power-law P(s){propto}s^-1.6^; there is no evidence in our data of any bimodality in this distribution for s<~1pc. Using radial velocities, we demonstrate that at large separations, i.e. of order s~1pc and beyond, any potential sample of genuine wide binaries in TGAS cannot be easily distinguished from ionized former wide binaries, moving groups or contamination from randomly aligned stars.
17377. Wide companions of low-mass stars and brown dwarfs
ID:
ivo://CDS.VizieR/J/AJ/133/971
Title:
Wide companions of low-mass stars and brown dwarfs
Short Name:
J/AJ/133/971
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a deep-imaging search for wide companions to low-mass stars and brown dwarfs using NSFCam on the Infrared Telescope Facility. We searched a sample of 132 M7-L8 dwarfs to magnitude limits of J~20.5 and K~18.5, corresponding to secondary-to-primary mass ratios of ~0.5. No companions were found with separations between 2" and 31" (~40 to ~1000AU). This null result implies a wide companion frequency below 2.3% at the 95% confidence level within the sensitivity limits of the survey. Preliminary modeling efforts indicate that we could have detected 85% of companions more massive than 0.05M_{sun}_ and 50% above 0.03M_{sun}_.
17378. Wide companions to M and L subdwarfs
ID:
ivo://CDS.VizieR/J/A+A/650/A190
Title:
Wide companions to M and L subdwarfs
Short Name:
J/A+A/650/A190
Date:
22 Feb 2022
Publisher:
CDS
Description:
The aim of the project is to identify wide common proper motion companions to a sample of spectroscopically confirmed M and L metal-poor dwarfs (also known as subdwarfs) to investigate the impact of metallicity on the binary fraction of low-mass metal-poor binaries and to improve the determination of their metallicity from the higher-mass binary. We made use of Virtual Observatory tools and large-scale public surveys to look in Gaia for common proper motion companions to a well-defined sample of ultracool subdwarfs with spectral types later than M5 and metallicities below or equal to ~0.5dex. We collected low-resolution optical spectroscopy for our best system, which is a binary composed of one sdM1.5 subdwarf and one sdM5.5 subdwarf located at ~1360au, and for another two likely systems separated by more than 115000au. We confirm one wide companion to an M subdwarf, and infer a multiplicity for M subdwarfs (sdMs) of 1.0_-1.0_^+2.0^% for projected physical separations of up to 743000au. We also find four M-L systems, three of which are new detections. No colder companion was identified in any of the 219 M and L subdwarfs of the sample, mainly because of limitations on the detection of faint sources with Gaia. We infer a frequency of wide systems for sdM5-9.5 of 0.60_-0.60_^+1.17^% for projected physical separations larger than 1360au (up to 142400au). This study shows a multiplicity rate of 1.0_-1.0_^+2.0^% in sdMs, and 1.9_-1.9_^+3.7^% in extreme M subdwarfs. We did not find any companion for the ultra M subdwarfs of our sample, establishing an upper limit of 5.3% on binarity for these objects.
17379. Wide field imagers ground-based astrometry. V.
ID:
ivo://CDS.VizieR/J/A+A/563/A80
Title:
Wide field imagers ground-based astrometry. V.
Short Name:
J/A+A/563/A80
Date:
21 Oct 2021
Publisher:
CDS
Description:
High-precision astrometry requires accurate point-spread function modeling and accurate geometric-distortion corrections. This paper demonstrates that it is possible to achieve both requirements with data collected at the High Acuity Wide-field K-band Imager (HAWK-I); a wide-field imager installed at the Nasmyth focus of UT4/VLT ESO 8m telescope. Our final astrometric precision reaches ~3mas per coordinate for a well exposed star in a single image, with a systematic error less than 0.1mas. We constructed calibrated astro-photometric catalogs and atlases of 7 fields: the Baade's window, NGC 6656, NGC 6121, NGC 6822, NGC 6388, NGC 104, and the James Webb Space Telescope calibration field (in the LMC). We make these catalogs and images electronically available to the community. Furthermore, as a demonstration of the efficacy of our approach, combining archival material taken with the optical wide-field imager at the MPI/ESO 2.2m with HAWK-I observations, we are able to achieve an excellent separation between cluster members and field objects for NGC 6656 and NGC 6121 with a time base-line of about 8 years. Using both HST and HAWK-I data, we also study the radial distribution of the SGB populations in NGC 6656 and conclude that the radial trend is flat, within our uncertains. We also provide membership probabilities for most of the stars in NGC 6656 and NGC 6121 catalogs and estimate membership for the published variable stars in these two fields.
17380. Wide-field NIR polarimetry of {rho} Oph cloud
ID:
ivo://CDS.VizieR/J/ApJS/220/17
Title:
Wide-field NIR polarimetry of {rho} Oph cloud
Short Name:
J/ApJS/220/17
Date:
21 Oct 2021
Publisher:
CDS
Description:
We conducted wide and deep simultaneous JHK_s_-band imaging polarimetry of the {rho} Ophiuchi cloud complex. Aperture polarimetry in the JHK_s_ band was conducted for 2136 sources in all three bands, of which 322 sources have significant polarizations in all the JHK_s_ bands and have been used for a discussion of the core magnetic fields. There is a positive correlation between degrees of polarization and H-K_s_ color up to H-K_s_~3.5. The magnetic field structures in the core region are revealed up to at least A_V_~47mag and are unambiguously defined in each sub-region (core) of Oph-A, Oph-B, Oph-C, Oph-E, Oph-F, and Oph-AC. Their directions, degrees of polarization, and polarization efficiencies differ but their changes are gradual; thus, the magnetic fields appear to be connected from core to core, rather than as a simple overlap of the different cloud core components. Comparing our results with the large-scale field structures obtained from previous optical polarimetric studies, we suggest that the magnetic field structures in the core were distorted by the cluster formation in this region, which may have been induced by shock compression due to wind/radiation from the Scorpius-Centaurus association.

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