- 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.
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3192. 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/MNRAS/380/199
- Title:
- SCUBA Half-Degree Extragalactic Survey. III
- Short Name:
- J/MNRAS/380/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Determining an accurate position for a submillimetre (submm) galaxy (SMG) is the crucial step that enables us to move from the basic properties of an SMG sample source counts and 2D clustering to an assessment of their detailed, multiwavelength properties, their contribution to the history of cosmic star formation and their links with present-day galaxy populations. In this paper, we identify robust radio and/or infrared (IR) counterparts, and hence accurate positions, for over two-thirds of the SCUBA HAlf-Degree Extragalactic Survey (SHADES) Source Catalogue, presenting optical, 24um and radio images of each SMG.
- ID:
- ivo://CDS.VizieR/J/MNRAS/379/1571
- Title:
- SCUBA Half-Degree Extragalactic Survey. IV
- Short Name:
- J/MNRAS/379/1571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the redshift distribution of the Submillimetre Common-User Bolometer Array (SCUBA) Half Degree Survey (SHADES) galaxy population based on the rest-frame radio-mm-far-infrared (FIR) colours of 120 robustly detected 850um sources in the Lockman Hole East (LH) and Subaru XMM-Newton Deep Field (SXDF). The redshift distribution derived from the full spectral energy distribution (SED) information is shown to be narrower than that determined from the radiosub-mm spectral index, as more photometric bands contribute to a higher redshift accuracy.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/MNRAS/436/1919
- Title:
- SCUBA observations of COSMOS galaxies
- Short Name:
- J/MNRAS/436/1919
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep 450{mu}m and 850{mu}m observations of a large, uniformly covered 394arcmin^2^ area in the Cosmic Evolution Survey (COSMOS) field obtained with the Scuba-2 instrument on the James Clerk Maxwell Telescope (JCMT). We achieve root-mean-square noise values of {sigma}_450_=4.13mJy and {sigma}_850_=0.80mJy. The differential and cumulative number counts are presented and compared to similar previous works. Individual point sources are identified at >3.6{sigma} significance, a threshold corresponding to a 3-5% sample contamination rate. We identify 78 sources at 450{mu}m and 99 at 850{mu}m, with flux densities S_450_=13-37mJy and S_850_=2-16mJy. Only 62-76% of 450{mu}m sources are 850{mu}m detected and 61-81% of 850{mu}m sources are 450{mu}m detected. The positional uncertainties at 450{mu}m are small (1-2.5 arcsec) and therefore allow a precise identification of multiwavelength counterparts without reliance on detection at 24{mu}m or radio wavelengths; we find that only 44% of 450{mu}m sources and 60% of 850{mu}m sources have 24{mu}m or radio counterparts. 450{mu}m selected galaxies peak at <z>=1.95+/-0.19 and 850{mu}m selected galaxies peak at <z>=2.16+/-0.11. The two samples occupy similar parameter space in redshift and luminosity, while their median SED peak wavelengths differ by ~20-50{mu}m (translating to {Delta}T_dust_=8-12K, where 450{mu}m selected galaxies are warmer). The similarities of the 450{mu}m and 850{mu}m populations, yet lack of direct overlap between them, suggests that submillimetre surveys conducted at any single far-infrared wavelength will be significantly incomplete (>~30%) at censusing infrared-luminous star formation at high z.
- 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).
- ID:
- ivo://CDS.VizieR/J/A+A/626/A15
- Title:
- Sculptor Red Giant Branch stars abundances
- Short Name:
- J/A+A/626/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present detailed chemical abundances for 99 Red Giant Branch stars in the centre of the Sculptor dwarf spheroidal galaxy, which have been obtained from high-resolution VLT/FLAMES spectroscopy. The abundances of Li, Na, alpha-elements (O, Mg, Si, Ca Ti), iron-peak elements (Sc, Cr, Fe, Co, Ni, Zn), r- and s-process elements (Ba, La, Nd, Eu) were all derived using stellar atmosphere models and semi-automated analysis techniques. The iron abundances, covering the range -2.3<[Fe/H]<-0.9, populate the whole metallicity distribution of the galaxy with the exception of the very low metallicity tail. There is a marked decrease in [{alpha}/Fe] over our sample, from the Galactic halo plateau value at low [Fe/H] and then, after a 'knee', a decrease to sub-solar [alpha/Fe] at high [Fe/H]. This is consistent with products of core-collapse supernovae dominating at early times, followed by the onset of supernovae type Ia as early as ~12Gyr ago. The products from low-mass AGB stars, as traced by the s-process, also participate in the chemical evolution of Sculptor with a timescale comparable to that of supernovae type Ia. However, the r-process is consistent with having no time delay relative to core-collapse supernovae, at least at the later stages of the chemical evolution in Sculptor. Using the simple and well-behaved chemical evolution of Sculptor, we further derive empirical constraints on the relative importance of massive stars and supernovae type Ia to the nucleosynthesis of individual iron-peak and alpha-elements. The most important contribution of supernovae typeIa is to the iron-peak elements: Fe, Cr and Mn; but there is also a modest but non-negligible contribution to both the heavier alpha-elements: S, Ca and Ti, and some of the iron-peak elements: Sc and Co. We see only very small or no contribution to O, Mg, Ni and Zn from supernovae type Ia in Sculptor. The observed chemical abundances in Sculptor show no evidence of a significantly different initial mass function, compared to that of the Milky Way. With the exception of neutron-capture elements at low [Fe/H], the scatter around mean trends in Sculptor for [Fe/H]>-2.3 is extremely low, and compatible with observational errors. Combined with the small scatter in the age-elemental abundances relation, this calls for an efficient mixing of metals in the gas in the centre of Sculptor since ~12Gyr ago.
