We present Atacama Large Millimetre Array and Atacama Compact Array observations of the Sunyaev-Zel’dovich effect in the z = 2 galaxy cluster Cl J1449+0856, an X-ray-detected progenitor of typical ...massive clusters in the present day Universe. While in a cleaned but otherwise untouched 92 GHz map of this cluster little to no negative signal is visible, careful subtraction of known sub-millimetre emitters in the uv plane reveals a decrement at 5σ significance. The total signal is −190 ± 36 μJy, with a peak offset by 5″–9″ (∼50 kpc) from both the X-ray centroid and the still-forming brightest cluster galaxy. A comparison of the recovered uv-amplitude profile of the decrement with different pressure models allows us to derive total mass constraints consistent with the ∼6 × 1013M⊙ estimated from X-ray data. Moreover, we find no strong evidence for a deviation of the pressure profile with respect to local galaxy clusters, although a slight tension at small-to-intermediate spatial scales suggests a flattened central profile, opposite to that seen in a cool core and possibly an AGN-related effect. This analysis of the lowest mass single SZ detection so far illustrates the importance of interferometers when observing the SZ effect in high-redshift clusters, the cores of which cannot be considered quiescent, such that careful subtraction of galaxy emission is necessary.
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We present images obtained with LABOCA of a sample of 22 galaxies selected via their red Herschel SPIRE colors. We aim to see if these luminous, rare, and distant galaxies are signposting dense ...regions in the early universe. Our 870 m survey covers an area of 1 deg2 down to an average rms of , with our five deepest maps going 2× deeper still. We catalog 86 dusty star-forming galaxies (DSFGs) around our "signposts," detected above a significance of 3.5 . This implies a overdensity of (or ) DSFGs, excluding our signposts, when comparing our number counts to those in "blank fields." Thus, we are 99.93% confident that our signposts are pinpointing overdense regions in the universe, and 95% 50% confident that these regions are overdense by a factor of at least ≥1.5 × 2×. Using template spectral energy distributions (SEDs) and SPIRE/LABOCA photometry, we derive a median photometric redshift of z = 3.2 0.2 for our signposts, with an inter-quartile range of z = 2.8-3.6, somewhat higher than expected for ∼850 m selected galaxies. We constrain the DSFGs that are likely responsible for this overdensity to within of their respective signposts. These "associated" DSFGs are radially distributed within (physical) distances of 1.6 0.5 Mpc from their signposts, have median star formation rates (SFRs) of (for a Salpeter stellar inital mass function) and median gas reservoirs of . These candidate protoclusters have average total SFRs of at least and space densities of ∼9 × 10−7 Mpc−3, consistent with the idea that their constituents may evolve to become massive early-type galaxies in the centers of the rich galaxy clusters we see today.
We present high-resolution maps of stars, dust, and molecular gas in a strongly lensed submillimeter galaxy (SMG) at z = 3.259. HATLAS J114637.9-001132 is selected from the Herschel-Astrophysical ...Terahertz Large Area Survey (H-ATLAS) as a strong lens candidate mainly based on its unusually high 500 mu m flux density (~300 mJy). It is the only high-redshift Planck detection in the 130 deg super(2) H-ATLAS Phase-I area. Keck Adaptive Optics images reveal a quadruply imaged galaxy in the K band while the Submillimeter Array and the Jansky Very Large Array show doubly imaged 880 mu m and CO(1 arrow right 0) sources, indicating differentiated distributions of the various components in the galaxy. In the source plane, the stars reside in three major kpc-scale clumps extended over ~1.6 kpc, the dust in a compact (~1 kpc) region ~3 kpc north of the stars, and the cold molecular gas in an extended (~7 kpc) disk ~5 kpc northeast of the stars. The emissions from the stars, dust, and gas are magnified by ~17, ~8, and ~7 times, respectively, by four lensing galaxies at z ~ 1. Intrinsically, the lensed galaxy is a warm (T sub(dust) ~ 40-65 K), hyper-luminous (L sub(IR) ~ 1.7 x 10 super(13) L sub(middot in circle); star formation rate (SFR) ~ 2000 M sub(middot in circle) yr super(-1)), gas-rich (M sub(gas)/M sub(baryon) ~ 70%), young (M sub(stellar)/SFR ~ 20 Myr), and short-lived (M sub(gas)/SFR ~ 40 Myr) starburst. With physical properties similar tounlensed z > 2 SMGs, HATLAS J114637.9-001132 offers a detailed view of a typical SMG through a powerful cosmic microscope.
Abstract
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 850 $\mu$m SCUBA-2 follow-up observations of 188 red DSFG candidates from the Herschel Multitiered Extragalactic Survey (HerMES) Large Mode Survey, covering 274 deg2. We detected 87 per cent with a signal-to-noise ratio >3 at 850 $\mu$m. 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 850 $\mu$m data provide a better constraint on the photometric redshifts of the candidates, with photometric redshift errors decreasing from σz/(1 + z) ≈ 0.21 to 0.15. Comparison spectroscopic redshifts also found little bias (〈(z − zspec)/(1 + zspec)〉 = 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 (≫103 M⊙ yr−1).
Abstract
We have modelled ∼0.1 arcsec resolution Atacama Large Millimetre/submillimeter Array imaging of six strong gravitationally lensed galaxies detected by the Herschel Space Observatory. Our ...modelling recovers mass properties of the lensing galaxies and, by determining magnification factors, intrinsic properties of the lensed submillimetre sources. We find that the lensed galaxies all have high ratios of star formation rate to dust mass, consistent with or higher than the mean ratio for high-redshift submillimetre galaxies and low-redshift ultra-luminous infrared galaxies. Source reconstruction reveals that most galaxies exhibit disturbed morphologies. Both the cleaned image plane data and the directly observed interferometric visibilities have been modelled, enabling comparison of both approaches. In the majority of cases, the recovered lens models are consistent between methods, all six having mass density profiles that are close to isothermal. However, one system with poor signal to noise shows mildly significant differences.
We report measurements of the carbon monoxide ground state rotational transition ( super(12)C super(16)O J = 1-0) with the Zpectrometer ultrawideband spectrometer on the 100 m diameter Green Bank ...Telescope. The sample comprises 11 galaxies with redshifts between z = 2.1 and 3.5 from a total sample of 24 targets identified by Herschel-ATLAS photometric colors from the SPIRE instrument. Nine of the CO measurements are new redshift determinations, substantially adding to the number of detections of galaxies with rest-frame peak submillimeter emission near 100 mu m. The CO detections confirm the existence of massive gas reservoirs within these luminous dusty starforming galaxies (DSFGs). The CO redshift distribution of the 350 mu m selected galaxies is strikingly similar to the optical redshifts of 850 mu -selected submillimeter galaxies in 2.1 < or =, slanted z < or = z, slanted 3.5. Spectroscopic redshifts break a temperature-redshift degeneracy; optically thin dust models fit to the far-infrared photometry indicate characteristic dust temperatures near 34 K for most of the galaxies we detect in CO. Detections of two warmer galaxies, and statistically significant nondetections, hint at warmer or molecule-poor DSFGs with redshifts that are difficult to determine from Herschel-SPIRE photometric colors alone. Many of the galaxies identified by H-ATLAS photometry are expected to be amplified by foreground gravitational lenses. Analysis of CO linewidths and luminosities provides a method for finding approximate gravitational lens magnifications mu from spectroscopic data alone, yielding mu ~ 3-20. Corrected for magnification, most galaxy luminosities are consistent with an ultraluminous infrared galaxy classification, but three are candidate hyper-LIRGs with luminosities greater than 10 super(13) L sub(middot in circle).
Context. Submillimetre galaxies (SMGs) represent an important source population in the origin and cosmic evolution of the most massive galaxies. Hence, it is imperative to place firm constraints on ...the fundamental physical properties of large samples of SMGs. Aims. We determine the physical properties of a sample of SMGs in the COSMOS field that were pre-selected at the observed-frame wavelength of λobs = 1.1 mm, and followed up at λobs = 1.3 mm with the Atacama Large Millimetre/submillimetre Array (ALMA). Methods. We used the MAGPHYS model package to fit the panchromatic (ultraviolet to radio) spectral energy distributions (SEDs) of 124 of the target SMGs, which lie at a median redshift of z = 2.30 (19.4% are spectroscopically confirmed). The SED analysis was complemented by estimating the gas masses of the SMGs by using the λobs = 1.3 mm dust emission as a tracer of the molecular gas component. Results. The sample median and 16th–84th percentile ranges of the stellar masses, obscured star formation rates, dust temperatures, and dust and gas masses were derived to be log(M⋆/M⊙) = 11.09+0.41-0.53, SFR = 402+661-233 M⊙ yr-1, Tdust = 39.7+9.7-7.4 K, log(Mdust/M⊙) = 9.01+0.20-0.31, and log(Mgas/M⊙ = 11.34+0.20-0.23, respectively. The Mdust/M⋆ ratio was found to decrease as a function of redshift, while the Mgas/Mdust ratio shows the opposite, positive correlation with redshift. The derived median gas-to-dust ratio of 120+73-30 agrees well with the canonical expectation. The gas fraction (Mgas/ (Mgas + M⋆)) was found to range from 0.10 to 0.98 with a median of 0.62+0.27-0.23. We found that 57.3% of our SMGs populate the main sequence (MS) of star-forming galaxies, while 41.9% of the sources lie above the MS by a factor of greater than three (one source lies below the MS). These super-MS objects, or starbursts, are preferentially found at z ≳ 3, which likely reflects the sensitivity limit of our source selection. We estimated that the median gas consumption timescale for our SMGs is ~535 Myr, and the super-MS sources appear to consume their gas reservoir faster than their MS counterparts. We found no obvious stellar mass–size correlations for our SMGs, where the sizes were measured in the observed-frame 3 GHz radio emission and rest-frame UV. However, the largest 3 GHz radio sizes are found among the MS sources. Those SMGs that appear irregular in the rest-frame UV are predominantly starbursts, while the MS SMGs are mostly disk-like. Conclusions. The physical parameter distributions of our SMGs and those of the equally bright, 870 μm selected SMGs in the ECDFS field (the so-called ALESS SMGs) are unlikely to be drawn from common parent distributions. This might reflect the difference in the pre-selection wavelength. Albeit being partly a selection bias, the abrupt jump in specific SFR and the offset from the MS of our SMGs at z ≳ 3 might also reflect a more efficient accretion from the cosmic gas streams, higher incidence of gas-rich major mergers, or higher star formation efficiency at z ≳ 3. We found a rather flat average trend between the SFR and dust mass, but a positive SFR−Mgas correlation. However, to address the questions of which star formation law(s) our SMGs follow, and how they compare with the Kennicutt-Schmidt law, the dust-emitting sizes of our sources need to be measured. Nonetheless, the larger radio-emitting sizes of the MS SMGs compared to starbursts is a likely indication of their more widespread, less intense star formation activity. The irregular rest-frame UV morphologies of the starburst SMGs are likely to echo their merger nature. The current stellar mass content of the studied SMGs is very high, so they must quench to form the so-called red-and-dead massive ellipticals. Our results suggest that the transition from high-z SMGs to local ellipticals via compact, quiescent galaxies (cQGs) at z ~ 2 might not be universal, and the latter population might also descend from the so-called blue nuggets. However, z ≳ 4 SMGs could be the progenitors of higher redshift, z ≳ 3 cQGs, while our results are also consistent with the possibility that ultra-massive early-type galaxies found at 1.2 ≲ z ≲ 2 experienced an SMG phase at z ≤ 3.
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Abstract
We present deep continuum observations at a wavelength of 2 mm centered on the COSMOS field using the Goddard IRAM Superconducting Millimeter Observer (GISMO) at the IRAM 30 m telescope. ...These data constitute the widest deep 2 mm survey to date, reaching a uniform
σ
∼ 0.23 mJy beam
−1
sensitivity over ∼250 arcmin
2
at ∼24″ resolution. We detect four sources at high significance (S/N ≥ 4.4) with an expected number of false detections of 0.09 sources and five sources at 4.4 > S/N ≥ 3.7 with an expected number of false detections of 1.65 sources. Combined with deep GISMO observations in GOODS-N, we constrain the 2 mm number counts over one decade in flux density. These measurements agree with most galaxy evolution models tested here, except those with a large population of dusty star-forming galaxies at
z
> 7. Five GISMO sources have counterparts in (sub)millimeter catalogs available in COSMOS. Their redshifts suggest that all but one lie above
z
∼ 3. These four high-redshift (
z
> 3) galaxies have
= 3.9, SFRs ∼ 400–1200
M
⊙
yr
−1
, and
M
dust
∼ 10
9.5
M
⊙
. They provide a relatively complete selection (∼66%) of the most luminous (
L
IR
> 10
12.6
L
⊙
) and highest-redshift (
z
> 3) galaxies detected within our survey area by AzTEC at 1.1 mm. We thus conclude that 2 mm surveys favor the selection of massive, vigorously star-forming, high-redshift galaxies. This is corroborated by GISMO-C4, a source with a low false-detection probability (∼6.2%), for which the absence of a (sub)millimeter counterpart supports a high-redshift origin (
z
≳ 3).
Abstract
We present the C II 158
μ
m line luminosity functions (LFs) at
z
∼ 4–6 using the ALMA observations of 118 sources, which are selected to have UV luminosity
M
1500Å
< −20.2 and optical ...spectroscopic redshifts in COSMOS and ECDF-S. Of the 118 targets, 75 have significant C II detections and 43 are upper limits. This is by far the largest sample of C II detections, which allows us to set constraints on the volume density of C II emitters at
z
∼ 4–6. But because this is a UV-selected sample, we are missing C II-bright but UV-faint sources, making our constraints strict lower limits. Our derived LFs are statistically consistent with the
z
∼ 0 C II LF at 10
8.25
–10
9.75
L
⊙
. We compare our results with the upper limits of the C II LF derived from serendipitous sources in the ALPINE maps. We also infer the C II LFs based on published far-IR and CO LFs at
z
∼ 4–6. Combining our robust lower limits with these additional estimates, we set further constraints on the true number density of C II emitters at
z
∼ 4–6. These additional LF estimates are largely above our LF at
L
CII
> 10
9
L
⊙
, suggesting that UV-faint but C II-bright sources likely make significant contributions to the C II emitter volume density. When we include all the LF estimates, we find that available model predictions underestimate the number densities of C II emitters at
z
∼ 4–6. Finally, we set a constraint on the molecular gas mass density at
z
∼ 4–6, with
ρ
mol
∼ (2–7) × 10
7
M
⊙
Mpc
−3
. This is broadly consistent with previous studies.
The ALPINE-ALMA [CII] survey Gruppioni, C.; Béthermin, M.; Loiacono, F. ...
Astronomy and astrophysics (Berlin),
11/2020, Volume:
643
Journal Article
Peer reviewed
Open access
Aims.
We present the detailed characterisation of a sample of 56 sources serendipitously detected in ALMA band 7 as part of the ALMA Large Program to INvestigate CII at Early Times (ALPINE). These ...sources, detected in COSMOS and ECDFS, have been used to derive the total infrared luminosity function (LF) and to estimate the cosmic star formation rate density (SFRD) up to
z
≃ 6.
Methods.
We looked for counterparts of the ALMA sources in all the available multi-wavelength (from HST to VLA) and photometric redshift catalogues. We also made use of deeper UltraVISTA and
Spitzer
source lists and maps to identify optically dark sources with no matches in the public catalogues. We used the sources with estimated redshifts to derive the 250
μ
m rest-frame and total infrared (8–1000
μ
m) LFs from
z
≃ 0.5 to 6.
Results.
Our ALMA blind survey (860
μ
m flux density range: ∼0.3–12.5 mJy) allows us to further push the study of the nature and evolution of dusty galaxies at high-
z
, identifying luminous and massive sources to redshifts and faint luminosities never probed before by any far-infrared surveys. The ALPINE data are the first ones to sample the faint end of the infrared LF, showing little evolution from
z
≃ 2.5 to
z
≃ 6, and a “flat” slope up to the highest redshifts (i.e. 4.5 <
z
< 6). The SFRD obtained by integrating the luminosity function remains almost constant between
z
≃ 2 and
z
≃ 6, and significantly higher than the optical or ultra-violet derivations, showing a significant contribution of dusty galaxies and obscured star formation at high-
z
. About 14% of all the ALPINE serendipitous continuum sources are found to be optically and near-infrared (near-IR) dark (to a depth
K
s
∼ 24.9 mag). Six show a counterpart only in the mid-IR and no HST or near-IR identification, while two are detected as C II emitters at
z
≃ 5. The six HST+near-IR dark galaxies with mid-IR counterparts are found to contribute about 17% of the total SFRD at
z
≃ 5 and to dominate the high-mass end of the stellar mass function at
z
> 3.
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