Search

Start Over Subject photometry Capability Type Simple Cone Search
4311. Sco OB2 intermediate-mass stars
ID:
ivo://CDS.VizieR/J/A+A/464/581
Title:
Sco OB2 intermediate-mass stars
Short Name:
J/A+A/464/581
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present JHK observations of 22 intermediate-mass stars in Sco OB2, obtained with NACO. This survey was performed to determine the status of (sub)stellar candidate companions of Sco OB2 member stars of spectral type A and late-B. The distinction between companions and background stars is made on the basis of a comparison to isochrones and additional statistical arguments. We include in our sample a subset of 9 targets with multi-color ADONIS observations from Kouwenhoven et al. (2005, Cat. <J/A+A/430/137>). We reanalyse the total sample (i.e. NACO and ADONIS) and conclude that of the 176 secondaries, 25 are physical companions, 55 are candidate companions, and 96 are background stars. Although we are sensitive (and complete) to brown dwarf companions as faint as K=14mag in the semi-major axis range 130-520AU, we detect only one, corresponding to a brown dwarf companion fraction of 0.5% (M>30M_Jupiter_). However, the number of brown dwarfs is consistent with an extrapolation of the (stellar) companion mass distribution into the brown dwarf regime. This indicates that the physical mechanism for the formation of brown dwarf companions around intermediate mass stars is similar to that of stellar companions, and that the embryo ejection mechanism does not need to be invoked in order to explain the small number of brown dwarf companions among intermediate mass stars in Sco OB2.
4312. Scorpius-Centaurus K-Type Stars
ID:
ivo://CDS.VizieR/J/MNRAS/461/794
Title:
Scorpius-Centaurus K-Type Stars
Short Name:
J/MNRAS/461/794
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of a spectroscopic survey for new K- and M-type members of Scorpius-Centaurus (Sco-Cen), the nearest OB Association (~100-200pc). Using an X-ray, proper motion and color-magnitude selected sample, we obtained spectra for 361 stars, for which we report spectral classifications and Li and Ha equivalent widths. We identified 156 new members of Sco-Cen, and recovered 51 previously published members. We have combined these with previously known members to form a sample of 493 solar-mass (~0.7-1.3M_[sun}_) members of Sco-Cen.We investigated the star-formation history of this sample, and re-assessed the ages of the massive main-sequence turn-off and the G-type members in all three subgroups. We performed a census for circumstellar disks in our sample using WISE infrared data and find a protoplanetary disk fraction for K-type stars of 4.4^+1.6^_-0.9_% for Upper Centaurus-Lupus and Lower Centaurus-Crux at ~16Myr and 9.0^+0.4^_-2.2_% for Upper Scorpius at~10Myr.
4313. S2COSMOS: bright SCUBA-2 submm sources in COSMOS
ID:
ivo://CDS.VizieR/J/ApJ/880/43
Title:
S2COSMOS: bright SCUBA-2 submm sources in COSMOS
Short Name:
J/ApJ/880/43
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present sensitive 850{mu}m imaging of the Cosmological Evolution Survey (COSMOS) field using 640hr of new and archival observations taken with SCUBA-2 at the East Asian Observatory's James Clerk Maxwell Telescope. The SCUBA-2 COSMOS survey (S2COSMOS) achieves a median noise level of {sigma}_850{mu}m_=1.2mJy/beam over an area of 1.6deg^2^ (MAIN; Hubble Space Telescope/Advanced Camera for Surveys footprint), and {sigma}_850{mu}m_=1.7mJy/beam over an additional 1deg^2^ of supplementary (supp) coverage. We present a catalog of 1020 and 127 sources detected at a significance level of >4{sigma} and >4.3{sigma} in the main and supp regions, respectively, corresponding to a uniform 2% false-detection rate. We construct the single-dish 850{mu}m number counts at S_850_>2mJy and show that these S2COSMOS counts are in agreement with previous single-dish surveys, demonstrating that degree-scale fields are sufficient to overcome the effects of cosmic variance in the S_850_=2-10mJy population. To investigate the properties of the galaxies identified by S2COSMOS sources we measure the surface density of near-infrared-selected galaxies around their positions and identify an average excess of 2.0+/-0.2 galaxies within a 13" radius (~100kpc at z~2). The bulk of these galaxies represent near-infrared-selected submillimeter galaxies and/or spatially correlated sources and lie at a median photometric redshift of z=2.0+/-0.1. Finally, we perform a stacking analysis at submillimeter and far-infrared wavelengths of stellar-mass-selected galaxies (M_*_=10^10^-10^12^M_{sun}_) from z=0-4, obtaining high-significance detections at 850{mu}m in all subsets (signal-to-noise ratio, S/N=4-30), and investigate the relation between far-infrared luminosity, stellar mass, and the peak wavelength of the dust spectral energy distribution. The publication of this survey adds a new deep, uniform submillimeter layer to the wavelength coverage of this well-studied COSMOS field.
4314. SCUBA-2 Cosmology Legacy Survey
ID:
ivo://CDS.VizieR/J/MNRAS/465/1789
Title:
SCUBA-2 Cosmology Legacy Survey
Short Name:
J/MNRAS/465/1789
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalogue of ~3000 submillimetre sources detected (>=3.5{sigma}) at 850um over ~5deg^2^ surveyed as part of the James Clerk Maxwell Telescope (JCMT) SCUBA-2 Cosmology Legacy Survey (S2CLS). This is the largest survey of its kind at 850um, increasing the sample size of 850um selected submillimetre galaxies by an order of magnitude. The wide 850um survey component of S2CLS covers the extragalactic fields: UKIDSS-UDS, COSMOS, Akari-NEP, Extended Groth Strip, Lockman Hole North, SSA22 and GOODS-North. The average 1{sigma} depth of S2CLS is 1.2mJy/beam, approaching the SCUBA-2 850um confusion limit, which we determine to be {sigma}_c_~=0.8mJy/beam. We measure the 850um number counts, reducing the Poisson errors on the differential counts to approximately 4 per cent at S850~=3mJy. With several independent fields, we investigate field-to-field variance, finding that the number counts on 0.5{deg}-1{deg} scales are generally within 50 per cent of the S2CLS mean for S850>3mJy, with scatter consistent with the Poisson and estimated cosmic variance uncertainties, although there is a marginal (2{sigma}) density enhancement in GOODS-North. The observed counts are in reasonable agreement with recent phenomenological and semi-analytic models, although determining the shape of the faint-end slope (S850<3mJy) remains a key test. The large solid angle of S2CLS allows us to measure the bright-end counts: at S850>10mJy there are approximately 10 sources per square degree, and we detect the distinctive up-turn in the number counts indicative of the detection of local sources of 850um emission, and strongly lensed high-redshift galaxies. All calibrated maps and the catalogue are made publicly available at https://zenodo.org/record/57792#.W41TsRg68eM .
4315. SCUBA-2 cosmology legacy survey
ID:
ivo://CDS.VizieR/J/MNRAS/436/430
Title:
SCUBA-2 cosmology legacy survey
Short Name:
J/MNRAS/436/430
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the multiwavelength properties of a sample of 450-{mu}m-selected sources from the SCUBA-2 Cosmology Legacy Survey. A total of 69 sources were identified above 4{sigma} in deep SCUBA-2 450-{mu}m observations overlapping the UDS and COSMOS fields and covering 210arcmin^2^ to a typical depth of {sigma}_450_=1.5mJy. Reliable cross-identifications are found for 58 sources (84 percent) in Spitzer and Hubble Space Telescope WFC3/IR data. The photometric redshift distribution (dN/dz) of 450-{mu}m-selected sources is presented, showing a broad peak in the redshift range 1<z<3 and a median of z=1.4. Combining the SCUBA-2 photometry with Herschel SPIRE data from HerMES, the submm spectral energy distribution (SED) is examined via the use of modified blackbody fits, yielding aggregate values for the IR luminosity, dust temperature and emissivity of <L_IR_>=10^12^+/-0.8L_{sun}_, <T_D_>=42+/-11K and <{beta}_D_>=1.6+/-0.5, respectively. The relationship between these SED parameters and the physical properties of galaxies is investigated, revealing correlations between T_D_ and L_IR_ and between {beta}D and both stellar mass and effective radius. The connection between the star formation rate (SFR) and stellar mass is explored, with 24 percent of 450-{mu}m sources found to be `starbursts', i.e. displaying anomalously high specific SFRs. However, both the number density and observed properties of these `starburst' galaxies are found to be consistent with the population of normal star-forming galaxies.
4316. SCUBA-2 EGS deep field
ID:
ivo://CDS.VizieR/J/MNRAS/464/3369
Title:
SCUBA-2 EGS deep field
Short Name:
J/MNRAS/464/3369
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep observations at 450 and 850{mu}m in the Extended Groth Strip field taken with the SCUBA-2 camera mounted on the James Clerk Maxwell Telescope as part of the deep SCUBA-2 Cosmology Legacy Survey (S2CLS), achieving a central instrumental depth of {sigma}_450_=1.2mJy/beam and {sigma}_850_=0.2mJy/beam. We detect 57 sources at 450{mu}m and 90 at 850{mu}m with signal-to-noise ratio >3.5 over ~70arcmin^2^. From these detections, we derive the number counts at flux densities S_450_>4.0mJy and S_850_>0.9mJy, which represent the deepest number counts at these wavelengths derived using directly extracted sources from only blank-field observations with a single-dish telescope. Our measurements smoothly connect the gap between previous shallower blank-field single-dish observations and deep interferometric ALMA results. We estimate the contribution of our SCUBA-2 detected galaxies to the cosmic infrared background (CIB), as well as the contribution of 24{mu}m-selected galaxies through a stacking technique, which add a total of 0.26+/-0.03 and 0.07+/-0.01MJy/sr, at 450 and 850{mu}m, respectively. These surface brightnesses correspond to 60+/-20 and 50+/-20 per cent of the total CIB measurements, where the errors are dominated by those of the total CIB. Using the photometric redshifts of the 24{mu}m-selected sample and the redshift distributions of the submillimetre galaxies, we find that the redshift distribution of the recovered CIB is different at each wavelength, with a peak at z~1 for 450{mu}m and at z~2 for 850{mu}m, consistent with previous observations and theoretical models.
4317. SCUBA-2 galaxies in 850um survey
ID:
ivo://CDS.VizieR/J/MNRAS/458/4321
Title:
SCUBA-2 galaxies in 850um survey
Short Name:
J/MNRAS/458/4321
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the properties of the galaxies selected from the deepest 850-{mu}m survey undertaken to date with (Submillimetre Common-User Bolometer Array 2) SCUBA-2 on the James Clerk Maxwell Telescope as part of the SCUBA-2 Cosmology Legacy Survey. A total of 106 sources (>5{sigma}) were uncovered at 850{mu}m from an area of ~=150 arcmin^2^ in the centre of the COSMOS/UltraVISTA/Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) field, imaged to a typical depth of {sigma}_850_~=0.25mJy. We utilize the available multifrequency data to identify galaxy counterparts for 80 of these sources (75 per cent), and to establish the complete redshift distribution for this sample, yielding . We have also been able to determine the stellar masses of the majority of the galaxy identifications, enabling us to explore their location on the star formation rate:stellar mass (SFR:M*) plane. Crucially, our new deep 850-{mu}m-selected sample reaches flux densities equivalent to SFR~=100M_{sun}_/yr, enabling us to confirm that sub-mm galaxies form the high-mass end of the 'main sequence' (MS) of star-forming galaxies at z>1.5 (with a mean specific SFR of sSFR=2.25+/-0.19Gyr^-1^ at z~=2.5). Our results are consistent with no significant flattening of the MS towards high masses at these redshifts. However, our results add to the growing evidence that average sSFR rises only slowly at high redshift, resulting in log_10_sSFR being an apparently simple linear function of the age of the Universe.
4318. SCUBA-2 high-redshift galaxies sample
ID:
ivo://CDS.VizieR/J/ApJ/784/9
Title:
SCUBA-2 high-redshift galaxies sample
Short Name:
J/ApJ/784/9
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use the James Clerk Maxwell Telescope's SCUBA-2 camera to image a 400 arcmin^2^ area surrounding the GOODS-N field. The 850 {mu}m rms noise ranges from a value of 0.49 mJy in the central region to 3.5 mJy at the outside edge. From these data, we construct an 850 {mu}m source catalog to 2 mJy containing 49 sources detected above the 4{sigma} level. We use an ultradeep (11.5 {mu}Jy at 5{sigma}) 1.4 GHz image obtained with the Karl G. Jansky Very Large Array together with observations made with the Submillimeter Array to identify counterparts to the submillimeter galaxies. For most cases of multiple radio counterparts, we can identify the correct counterpart from new and existing Submillimeter Array data. We have spectroscopic redshifts for 62% of the radio sources in the 9' radius highest sensitivity region (556/894) and 67% of the radio sources in the GOODS-N region (367/543). We supplement these with a modest number of additional photometric redshifts in the GOODS-N region (30). We measure millimetric redshifts from the radio to submillimeter flux ratios for the unidentified submillimeter sample, assuming an Arp 220 spectral energy distribution. We find a radio-flux-dependent K-z relation for the radio sources, which we use to estimate redshifts for the remaining radio sources. We determine the star formation rates (SFRs) of the submillimeter sources based on their radio powers and their submillimeter fluxes and find that they agree well. The radio data are deep enough to detect star-forming galaxies with SFRs>2000 M_{sun}_/yr to z~6. We find galaxies with SFRs up to ~6000 M_{sun}_/yr over the redshift range z=1.5-6, but we see evidence for a turn-down in the SFR distribution function above 2000 M_{sun}_/yr.
4319. SCUBA-2 & LABOCA obs. of HATLAS ultrared galaxies
ID:
ivo://CDS.VizieR/J/ApJ/832/78
Title:
SCUBA-2 & LABOCA obs. of HATLAS ultrared galaxies
Short Name:
J/ApJ/832/78
Date:
21 Oct 2021
Publisher:
CDS
Description:
Until recently, only a handful of dusty, star-forming galaxies (DSFGs) were known at z>4, most of them significantly amplified by gravitational lensing. Here, we have increased the number of such DSFGs substantially, selecting galaxies from the uniquely wide 250, 350, and 500{mu}m Herschel-ATLAS imaging survey on the basis of their extremely red far-infrared colors and faint 350 and 500{mu}m flux densities, based on which, they are expected to be largely unlensed, luminous, rare, and very distant. The addition of ground-based continuum photometry at longer wavelengths from the James Clerk Maxwell Telescope and the Atacama Pathfinder Experiment allows us to identify the dust peak in their spectral energy distributions (SEDs), with which we can better constrain their redshifts. We select the SED templates that are best able to determine photometric redshifts using a sample of 69 high-redshift, lensed DSFGs, then perform checks to assess the impact of the CMB on our technique, and to quantify the systematic uncertainty associated with our photometric redshifts, {sigma}=0.14(1+z), using a sample of 25 galaxies with spectroscopic redshifts, each consistent with our color selection. For Herschel-selected ultrared galaxies with typical colors of S_500_/S_250_~2.2 and S_500_/S_350_~1.3 and flux densities, S500~50mJy, we determine a median redshift, z_phot_=3.66, an interquartile redshift range, 3.30-4.27, with a median rest-frame 8-1000{mu}m luminosity, L_IR_, of 1.3x10^13^L_{sun}_. A third of the galaxies lie at z>4, suggesting a space density, {rho}_z>4_, of ~6x10^-7^Mpc^-3^. Our sample contains the most luminous known star-forming galaxies, and the most overdense cluster of starbursting proto-ellipticals found to date.
4320. SCUBA-2 850um obs. of Herschel gal.
ID:
ivo://CDS.VizieR/J/MNRAS/477/1099
Title:
SCUBA-2 850um obs. of Herschel gal.
Short Name:
J/MNRAS/477/1099
Date:
21 Oct 2021
Publisher:
CDS
Description:
High-redshift, luminous, dusty star-forming galaxies (DSFGs) constrain the extremity of galaxy formation theories. The most extreme are discovered through follow-up on candidates in large area surveys. Here, we present extensive 850um SCUBA-2 follow-up observations of 188 red DSFG candidates from the Herschel Multitiered Extragalactic Survey (HerMES) Large Mode Survey, covering 274deg^2^. We detected 87% with a signal-to-noise ratio >3 at 850um. We introduce a new method for incorporating the confusion noise in our spectral energy distribution fitting by sampling correlated flux density fluctuations from a confusion limited map. The new 850um data provide a better constraint on the photometric redshifts of the candidates, with photometric redshift errors decreasing from {sigma}_z_/(1+z)~0.21 to 0.15. Comparison spectroscopic redshifts also found little bias (<(z-z_spec_)/(1+z_spec_)>=0.08). The mean photometric redshift is found to be 3.6 with a dispersion of 0.4 and we identify 21 DSFGs with a high probability of lying at z>4. After simulating our selection effects we find number counts are consistent with phenomenological galaxy evolution models. There is a statistically significant excess of WISE-1 and SDSS sources near our red galaxies, giving a strong indication that lensing may explain some of the apparently extreme objects. Nevertheless, our sample includes examples of galaxies with the highest star formation rates in the Universe (>>10^3^M_{sun}_/yr).