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1981. Candidate halo wide binaries
ID:
ivo://CDS.VizieR/J/ApJ/790/158
Title:
Candidate halo wide binaries
Short Name:
J/ApJ/790/158
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an improved catalog of halo wide binaries compiled from an extensive literature search. Most of our binaries stem from the common proper motion binary catalogs by Allen et al. (2000, J/A+A/356/529) and Chaname & Gould (2004ApJ...601..289C), but we have also included binaries from the lists of Ryan (1992AJ....104.1144R) and Zapatero-Osorio & Martin (2004, J/A+A/419/167). All binaries were carefully checked and their distances and systemic radial velocities are included when available. Probable membership to the halo population was tested by means of reduced proper motion diagrams for 251 candidate halo binaries. After eliminating obvious disk binaries, we ended up with 211 probable halo binaries, 150 of which have radial velocities available. We compute galactic orbits for these 150 binaries and calculate the time they spend within the galactic disk. Considering the full sample of 251 candidate halo binaries as well as several subsamples, we find that the distribution of angular separations (or expected major semiaxes) follows a power law f(a) ~ a.^-1^ (Oepik's relation) up to different limits. For the 50 most disk-like binaries, those that spend their entire lives within z = +/-500 pc, this limit is found to be 19,000 AU (0.09 pc), while for the 50 most halo-like binaries, those that spend on average only 18% of their lives within z = +/-500 pc, the limit is 63,000 AU (0.31 pc). In a companion paper, we employ this catalog to establish limits on the masses of the halo massive perturbers (massive compact halo objects).
1982. Candidate Halpha sources in GBS
ID:
ivo://CDS.VizieR/J/MNRAS/466/163
Title:
Candidate Halpha sources in GBS
Short Name:
J/MNRAS/466/163
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalogue of candidate Halpha emission and absorption line sources and blue objects in the Galactic Bulge Survey (GBS) region. We use a point source catalogue of the GBS fields (two strips of (lxb)=(6{deg}x1{deg}) centred at b=1.5{deg} above and below the Galactic centre), covering the magnitude range 16>=r'>=22.5. We utilize (r'-i', r'-Halpha) colour-colour diagrams to select Halpha emission and absorption line candidates, and also identify blue objects (compared to field stars) using the r'-i' colour index. We identify 1337 Halpha emission line candidates and 336 Halpha absorption line candidates. These catalogues likely contain a plethora of sources, ranging from active (binary) stars, early-type emission line objects, cataclysmic variables (CVs) and low-mass X-ray binaries (LMXBs) to background active galactic nuclei (AGN). The 389 blue objects we identify are likely systems containing a compact object, such as CVs, planetary nebulae and LMXBs. Hot subluminous dwarfs (sdO/B stars) are also expected to be found as blue outliers. Crossmatching our outliers with the GBS X-ray catalogue yields sixteen sources, including seven (magnetic) CVs and one qLMXB candidate among the emission line candidates, and one background AGN for the absorption line candidates. One of the blue outliers is a high state AM CVn system. Spectroscopic observations combined with the multi-wavelength coverage of this area, including X-ray, ultraviolet and (time-resolved) optical and infrared observations, can be used to further constrain the nature of individual sources.
1983. Candidate high-z protoclusters among PCS
ID:
ivo://CDS.VizieR/J/MNRAS/476/3336
Title:
Candidate high-z protoclusters among PCS
Short Name:
J/MNRAS/476/3336
Date:
21 Oct 2021
Publisher:
CDS
Description:
By determining the nature of all the Planck compact sources within 808.4deg^2^ of large Herschel surveys, we have identified 27 candidate protoclusters of dusty star-forming galaxies (DSFGs) that are at least 3{sigma} overdense in either 250, 350, or 500um sources. We find roughly half of all the Planck compact sources are resolved by Herschel into multiple discrete objects, with the other half remaining unresolved by Herschel. We find a significant difference between versions of the Planck catalogues, with earlier releases hosting a larger fraction of candidate protoclusters and Galactic cirrus than later releases, which we ascribe to a difference in the filters used in the creation of the three catalogues. We find a surface density of DSFG candidate protoclusters of (3.3+/-0.7)x10^-2^sources/deg^2^, in good agreement with previous similar studies. We find that a Planck colour selection of S_857_/S_545_<2 works well to select candidate protoclusters, but can miss protoclusters at z<2. The Herschel colours of individual candidate protocluster members indicate our candidate protoclusters all likely all lie at z>1. Our candidate protoclusters are a factor of 5 times brighter at 353GHz than expected from simulations, even in the most conservative estimates. Further observations are needed to confirm whether these candidate protoclusters are physical clusters, multiple protoclusters along the line of sight, or chance alignments of unassociated sources.
1984. Candidate ICRF flat-spectrum radio sources. III.
ID:
ivo://CDS.VizieR/J/AJ/153/157
Title:
Candidate ICRF flat-spectrum radio sources. III.
Short Name:
J/AJ/153/157
Date:
21 Oct 2021
Publisher:
CDS
Description:
In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ~160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58m European Southern Observatory New Technology Telescope, and the two 8.2m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.
1985. Candidate IR variables from SAGE-SMC survey
ID:
ivo://CDS.VizieR/J/AJ/149/78
Title:
Candidate IR variables from SAGE-SMC survey
Short Name:
J/AJ/149/78
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present our study on the infrared variability of point sources in the Small Magellanic Cloud (SMC). We use the data from the Spitzer Space Telescope Legacy Program "Surveying the Agents of Galaxy Evolution in the Tidally Stripped, Low Metallicity Small Magellanic Cloud" (SAGE-SMC) and the "Spitzer Survey of the Small Magellanic Cloud" (S^3^MC) survey, over three different epochs, separated by several months to 3 years. Variability in the thermal infrared is identified using a combination of Spitzer's InfraRed Array Camera 3.6, 4.5, 5.8, and 8.0{mu}m bands, and the Multiband Imaging Photometer for Spitzer 24{mu}m band. An error-weighted flux difference between each pair of three epochs ("variability index") is used to assess the variability of each source. A visual source inspection is used to validate the photometry and image quality. Out of ~2 million sources in the SAGE-SMC catalog, 814 meet our variability criteria. We matched the list of variable star candidates to the catalogs of SMC sources classified with other methods, available in the literature. Carbon-rich Asymptotic Giant Branch (AGB) stars make up the majority (61%) of our variable sources, with about a third of all of our sources being classified as extreme AGB stars. We find a small, but significant population of oxygen-rich (O-rich) AGB (8.6%), Red Supergiant (2.8%), and Red Giant Branch (<1%) stars. Other matches to the literature include Cepheid variable stars (8.6%), early type stars (2.8%), Young-stellar objects (5.8%), and background galaxies (1.2%). We found a candidate OH maser star, SSTISAGE1C J005212.88-730852.8, which is a variable O-rich AGB star, and would be the first OH/IR star in the SMC, if confirmed. We measured the infrared variability of a rare RV Tau variable (a post-AGB star) that has recently left the AGB phase. 59 variable stars from our list remain unclassified.
1986. Candidate LAEs at z=5.7 and z=6.6
ID:
ivo://CDS.VizieR/J/MNRAS/472/772
Title:
Candidate LAEs at z=5.7 and z=6.6
Short Name:
J/MNRAS/472/772
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present spectroscopic follow-up of candidate luminous Ly{alpha} emitters (LAEs) at z=5.7-6.6 in the SA22 field with VLT/X-SHOOTER. We confirm two new luminous LAEs at z=5.676 (SR6) and z=6.532 (VR7), and also present HST follow-up of both sources. These sources have luminosities L_Ly {alpha}_~=3x10^43^erg/s, very high rest-frame equivalent widths of EW_0_>=200{AA} and narrow Ly{alpha} lines (200-340km/s). VR7 is the most UV-luminous LAE at z>6.5, with M_1500_=-22.5, even brighter in the UV than CR7. Besides Ly{alpha}, we do not detect any other rest-frame UV lines in the spectra of SR6 and VR7, and argue that rest-frame UV lines are easier to observe in bright galaxies with low Ly{alpha} equivalent widths. We confirm that Ly{alpha} line widths increase with Ly{alpha} luminosity at z=5.7, while there are indications that Ly{alpha} lines of faint LAEs become broader at z=6.6, potentially due to reionization. We find a large spread of up to 3 dex in UV luminosity for >L* LAEs, but find that the Ly{alpha} luminosity of the brightest LAEs is strongly related to UV luminosity at z=6.6. Under basic assumptions, we find that several LAEs at z~=6-7 have Ly{alpha} escape fractions >=100 per cent, indicating bursty star formation histories, alternative Ly{alpha} production mechanisms, or dust attenuating Ly{alpha} emission differently than UV emission. Finally, we present a method to compute {xi}_ion_, the production efficiency of ionizing photons, and find that LAEs at z~=6-7 have high values of log_10_({xi}_ion_/Hz/erg)~=25.51+/-0.09 that may alleviate the need for high Lyman-Continuum escape fractions required for reionization.
1987. Candidate low-mass PMS in 25 Orionis group
ID:
ivo://CDS.VizieR/J/AJ/131/2959
Title:
Candidate low-mass PMS in 25 Orionis group
Short Name:
J/AJ/131/2959
Date:
21 Oct 2021
Publisher:
CDS
Description:
The stellar group surrounding the Be (B1Vpe) star 25 Ori was discovered to be a pre-main-sequence (PMS) population by the CIDA Variability Survey of Orion (Cat. J/AJ/129/907) and subsequent spectroscopy. We analyze Sloan Digital Sky Survey multiepoch photometry to map the southern extent of the 25 Ori group and characterize its PMS population. We compare this group to the neighboring Orion OB1a and OB1b subassociations and to active star formation sites (NGC 2068/NGC 2071) within the LDN 1630 dark cloud. We find that the 25 Ori group has a radius of 1.4{deg}, corresponding to 8-11pc at the distances of Orion OB1a and OB1b.
1988. Candidate Ly{alpha} emitting galaxies
ID:
ivo://CDS.VizieR/J/A+A/461/823
Title:
Candidate Ly{alpha} emitting galaxies
Short Name:
J/A+A/461/823
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a large program conducted with the Very Large Telescope and augmented by observations with the Keck telescope to search for forming clusters of galaxies near powerful radio galaxies at 2.0<z<5.2. Besides MRC 1138-262 at z=2.16, the radio galaxy observed in our pilot program, we obtained narrow- and broad-band images of eight radio galaxies and their surroundings. The imaging was used to select candidate Ly{alpha} emitting galaxies in ~3x3Mpc^2^ areas near the radio galaxies. A total of 300 candidate emitters were found with a rest-frame Ly{alpha} equivalent width of EW0>15{AA} and significance Sigma{equiv.to}(EW0/DEW0)>3. Follow-up spectroscopy was performed on 152 candidates in seven of the radio galaxy fields. Of these, 139 were confirmed to be Ly{alpha} emitters, four were low redshift interlopers and nine were non-detections. With the adopted criteria the success rate is 139/152=91%. In addition, 14 objects with EW0<15 and/or Sigma<3 were confirmed to be Ly{alpha} emitters. Combined with the 15 Ly{alpha} emitters near MRC 1138-262, we have determined Ly{alpha} redshifts for 168 objects near eight radio galaxies.
1989. Candidate Ly{alpha} emitting galaxies at z~3.8
ID:
ivo://CDS.VizieR/J/ApJ/823/11
Title:
Candidate Ly{alpha} emitting galaxies at z~3.8
Short Name:
J/ApJ/823/11
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new observations of the field containing the z=3.786 protocluster PC 217.96+32.3. We confirm that it is one of the largest known and most overdense high-redshift structures. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1.2x0.6{deg} area (~150x75 comoving Mpc) surrounding the protocluster's core and discovered 165 candidate Ly{alpha} emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least two overdense regions traced by the LAEs, the largest of which shows an areal overdensity in its core (i.e., within a radius of 2.5 comoving Mpc) of 14+/-7 relative to the average LAE spatial density (\bar{rho}) in the imaged field. Further, \bar{rho} is twice that derived by other field LAE surveys. Spectroscopy with Keck/DEIMOS yielded redshifts for 164 galaxies (79 LAEs and 85 LBGs); 65 lie at a redshift of 3.785+/-0.010. The velocity dispersion of galaxies near the core is {sigma}=350+/-40km/s, a value robust to selection effects. The overdensities are likely to collapse into systems with present-day masses of >10^15^M_{sun}_ and >6x10^14^M_{sun}_. The low velocity dispersion may suggest a dynamically young protocluster. We find a weak trend between narrow-band (Ly{alpha}) luminosity and environmental density: the Ly{alpha} luminosity is enhanced on average by 1.35x within the protocluster core. There is no evidence that the Ly{alpha} equivalent width depends on environment. These suggest that star formation and/or active galactic nucleus (AGN) activity is enhanced in the higher-density regions of the structure. PC 217.96+32.3 is a Coma cluster analog, witnessed in the process of formation.
1990. Candidate members of {beta} Pic / AB Dor groups
ID:
ivo://CDS.VizieR/J/AJ/143/134
Title:
Candidate members of {beta} Pic / AB Dor groups
Short Name:
J/AJ/143/134
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present moderate resolution (R~3575) optical spectra of 19 known or suspected members of the AB Doradus and {beta} Pictoris Moving Groups, obtained with the DeVeny Spectrograph on the 72inch Perkins telescope at Lowell Observatory. For four of five recently proposed members, signatures of youth such as LiI 6708{AA} absorption and H{alpha} emission further strengthen the case for youth and membership. The lack of detected lithium in the proposed {beta} Pic member TYC 2211-1309-1 implies that it is older than all other K-type members and weakens the case for membership. Effective temperatures are determined via line ratio analyses for the 11 F, G, and early-K stars observed, and via spectral comparisons for the eight late-K and M stars observed. We assemble updated candidate membership lists for these moving groups that account for known binarity. Currently, the AB Dor Moving Group contains 127 proposed members and the {beta} Pic Moving Group holds 77 proposed members. We then use temperature, luminosity, and distance estimates to predict angular diameters for these stars; the motivation is to identify stars that can be spatially resolved with long-baseline optical/infrared interferometers in order to improve age estimates for these groups and to constrain evolutionary models at young ages. Considering the portion of the sky accessible to northern hemisphere facilities (DE>-30), six stars have diameters large enough to be spatially resolved ({theta}>0.4mas) with the CHARA Array, which currently has the world's longest baseline of 331m; this subsample includes the low-mass M2.5 member of AB Dor, GJ 393, which is likely to still be pre-main sequence. For southern hemisphere facilities (DE<+30), 18 stars have diameters larger than this limiting size, including the low-mass debris disk star AU Mic (0.72mas). However, the longest baselines of southern hemisphere interferometers (160m) are only able to resolve the largest of these, the B6 star {alpha} Gru (1.17mas); proposed long-baseline stations may alleviate the current limitations.

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