scholarly journals SuperCLASS – II. Photometric redshifts and characteristics of spatially resolved μJy radio sources

2020 ◽  
Vol 495 (2) ◽  
pp. 1724-1736 ◽  
Author(s):  
Sinclaire M Manning ◽  
Caitlin M Casey ◽  
Chao-Ling Hung ◽  
Richard Battye ◽  
Michael L Brown ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Spectral Energy ◽  
Radio Sources ◽  
Photometric Redshifts ◽  
Very Large Array ◽  
Star Forming ◽  
Photometric Redshift ◽  
Spatially Resolved ◽  
Density Map

ABSTRACT We present optical and near-infrared imaging covering a ∼1.53 deg2 region in the Super-Cluster Assisted Shear Survey (SuperCLASS) field, which aims to make the first robust weak lensing measurement at radio wavelengths. We derive photometric redshifts for ≈176 000 sources down to $i^\prime _{\rm AB}\sim 24$ and present photometric redshifts for 1.4 GHz expanded Multi-Element Radio Linked Interferometer Network (e-MERLIN) and Karl G. Jansky Very Large Array (VLA) detected radio sources found in the central 0.26 deg2. We compile an initial catalogue of 149 radio sources brighter than S1.4 > 75 μJy and find their photometric redshifts span 0 < zphot < 4 with radio luminosities between 1021 and 1025 W Hz−1, with medians of $\langle z \rangle \, =0.55$ and $\langle L_{1.4}\rangle \, =1.9\times 10^{23}$ W Hz−1, respectively. We find 95 per cent of the μJy radio source sample (141/149) have spectral energy distributions (SEDs) best fit by star-forming templates while 5 per cent (8/149) are better fit by active galactic nuclei (AGN). Spectral indices are calculated for sources with radio observations from the VLA and Giant Metrewave Radio Telescope (GMRT) at 325 MHz, with an average spectral slope of α = 0.59 ± 0.04. Using the full photometric redshift catalogue, we construct a density map at the redshift of the known galaxy clusters, z = 0.20 ± 0.08. Four of the five clusters are prominently detected at $\gt 7\, \sigma$ in the density map and we confirm the photometric redshifts are consistent with previously measured spectra from a few galaxies at the cluster centres.

scholarly journals Mapping Obscuration to Reionization with ALMA (MORA): 2 mm Efficiently Selects the Highest-redshift Obscured Galaxies

2021 ◽  
Vol 923 (2) ◽  
pp. 215
Author(s):  
Caitlin M. Casey ◽  
Jorge A. Zavala ◽  
Sinclaire M. Manning ◽  
Manuel Aravena ◽  
Matthieu Béthermin ◽  
...  
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Formation Rate ◽  
Dust Emission ◽  
Volume Density ◽  
Drop Out ◽  
Spectral Energy ◽  
Photometric Redshifts ◽  
Star Forming ◽  
Dusty Galaxies

Abstract We present the characteristics of 2 mm selected sources from the largest Atacama Large Millimeter/submillimeter Array (ALMA) blank-field contiguous survey conducted to date, the Mapping Obscuration to Reionization with ALMA (MORA) survey covering 184 arcmin2 at 2 mm. Twelve of 13 detections above 5σ are attributed to emission from galaxies, 11 of which are dominated by cold dust emission. These sources have a median redshift of 〈 z 2 mm 〉 = 3.6 − 0.3 + 0.4 primarily based on optical/near-infrared photometric redshifts with some spectroscopic redshifts, with 77% ± 11% of sources at z > 3 and 38% ± 12% of sources at z > 4. This implies that 2 mm selection is an efficient method for identifying the highest-redshift dusty star-forming galaxies (DSFGs). Lower-redshift DSFGs (z < 3) are far more numerous than those at z > 3 yet are likely to drop out at 2 mm. MORA shows that DSFGs with star formation rates in excess of 300 M ⊙ yr−1 and a relative rarity of ∼10−5 Mpc−3 contribute ∼30% to the integrated star formation rate density at 3 < z < 6. The volume density of 2 mm selected DSFGs is consistent with predictions from some cosmological simulations and is similar to the volume density of their hypothesized descendants: massive, quiescent galaxies at z > 2. Analysis of MORA sources’ spectral energy distributions hint at steeper empirically measured dust emissivity indices than reported in typical literature studies, with 〈 β 〉 = 2.2 − 0.4 + 0.5 . The MORA survey represents an important step in taking census of obscured star formation in the universe’s first few billion years, but larger area 2 mm surveys are needed to more fully characterize this rare population and push to the detection of the universe’s first dusty galaxies.

scholarly journals SCUBA-2 observations of candidate starbursting protoclusters selected by Planck and Herschel-SPIRE

2019 ◽  
Vol 490 (3) ◽  
pp. 3840-3859 ◽  
Author(s):  
T Cheng ◽  
D L Clements ◽  
J Greenslade ◽  
J Cairns ◽  
P Andreani ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Spectral Energy ◽  
Cumulative Number ◽  
Redshift Distribution ◽  
Photometric Redshifts ◽  
Star Forming ◽  
Photometric Redshift

ABSTRACT We present SCUBA-2 850 $\mathrm{ \mu}$m observations of 13 candidate starbursting protoclusters selected using Planck and Herschel data. The cumulative number counts of the 850 $\mathrm{ \mu}$m sources in 9 of 13 of these candidate protoclusters show significant overdensities compared to the field, with the probability &lt;10−2 assuming the sources are randomly distributed in the sky. Using the 250, 350, 500, and 850 $\mathrm{ \mu}$m flux densities, we estimate the photometric redshifts of individual SCUBA-2 sources by fitting spectral energy distribution templates with an MCMC method. The photometric redshift distribution, peaking at 2 &lt; z &lt; 3, is consistent with that of known z &gt; 2 protoclusters and the peak of the cosmic star formation rate density (SFRD). We find that the 850 $\mathrm{ \mu}$m sources in our candidate protoclusters have infrared luminosities of $L_{\mathrm{IR}}\gtrsim 10^{12}\, \mathrm{L}_{\odot }$ and star formation rates of SFR  = (500–1500) M⊙ yr−1. By comparing with results in the literature considering only Herschel photometry, we conclude that our 13 candidate protoclusters can be categorized into four groups: six of them being high-redshift starbursting protoclusters, one being a lower redshift cluster or protocluster, three being protoclusters that contain lensed dusty star-forming galaxies or are rich in 850 $\mathrm{ \mu}$m sources, and three regions without significant Herschel or SCUBA-2 source overdensities. The total SFRs of the candidate protoclusters are found to be comparable or higher than those of known protoclusters, suggesting our sample contains some of the most extreme protocluster population. We infer that cross-matching Planck and Herschel data is a robust method for selecting candidate protoclusters with overdensities of 850 $\mathrm{ \mu}$m sources.

scholarly journals A lack of evolution in the very bright end of the galaxy luminosity function from z ≃ 8 to 10

2020 ◽  
Vol 493 (2) ◽  
pp. 2059-2084 ◽  
Author(s):  
R A A Bowler ◽  
M J Jarvis ◽  
J S Dunlop ◽  
R J McLure ◽  
D J McLeod ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Luminosity Function ◽  
Near Infrared ◽  
Good Description ◽  
Number Density ◽  
Photometric Redshifts ◽  
Star Forming ◽  
Photometric Redshift ◽  
Wide Range ◽  
Best Fitting

ABSTRACT We utilize deep near-infrared survey data from the UltraVISTA fourth data release (DR4) and the VIDEO survey, in combination with overlapping optical and Spitzer data, to search for bright star-forming galaxies at z ≳ 7.5. Using a full photometric redshift fitting analysis applied to the ∼6 $\, {\rm deg}^2$ of imaging searched, we find 27 Lyman break galaxies (LBGs), including 20 new sources, with best-fitting photometric redshifts in the range 7.4 &lt; z &lt; 9.1. From this sample, we derive the rest-frame UV luminosity function at z = 8 and z = 9 out to extremely bright UV magnitudes (MUV ≃ −23) for the first time. We find an excess in the number density of bright galaxies in comparison to the typically assumed Schechter functional form derived from fainter samples. Combined with previous studies at lower redshift, our results show that there is little evolution in the number density of very bright (MUV ∼ −23) LBGs between z ≃ 5 and z ≃ 9. The tentative detection of an LBG with best-fitting photometric redshift of z = 10.9 ± 1.0 in our data is consistent with the derived evolution. We show that a double power-law fit with a brightening characteristic magnitude (ΔM*/Δz ≃ −0.5) and a steadily steepening bright-end slope (Δβ/Δz ≃ −0.5) provides a good description of the z &gt; 5 data over a wide range in absolute UV magnitude (−23 &lt; MUV &lt; −17). We postulate that the observed evolution can be explained by a lack of mass quenching at very high redshifts in combination with increasing dust obscuration within the first ${\sim}1 \, {\rm Gyr}$ of galaxy evolution.

scholarly journals Pre-processing of galaxies in cosmic filaments around AMASCFI clusters in the CFHTLS

2019 ◽  
Vol 632 ◽  
pp. A49 ◽  
Author(s):  
F. Sarron ◽  
C. Adami ◽  
F. Durret ◽  
C. Laigle
Keyword(s):  
Galaxy Clusters ◽  
Spectral Energy ◽  
Photometric Redshifts ◽  
Star Forming ◽  
Galaxy Groups ◽  
Photometric Redshift ◽  
Preferred Direction ◽  
The Galaxy ◽  
Strategic Program ◽  
Galaxy Populations

Context. Galaxy clusters and groups are thought to accrete material along the preferred direction of cosmic filaments. These structures have proven difficult to detect because their contrast is low, however, and only a few studies have focused on cluster infall regions. Aims. We detect cosmic filaments around galaxy clusters using photometric redshifts in the range 0.15 <  z <  0.7. We characterise galaxy populations in these structures to study the influence of pre-processing by cosmic filaments and galaxy groups on star formation quenching. Methods. We detected cosmic filaments in the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) T0007 data, focusing on regions around clusters of the AMASCFI CFHTLS cluster sample. The filaments were reconstructed with the discrete persistent structure extractor (DISPERSE) algorithm in photometric redshift slices. We show that this reconstruction is reliable for a CFHTLS-like survey at 0.15 <  z <  0.7 using a mock galaxy catalogue. We split our galaxy catalogue into two populations (passive and star forming) using the LePhare spectral energy density fitting algorithm and worked with two redshift bins (0.15 <  z ≤ 0.4 and 0.4 <  z <  0.7). Results. We showed that the AMASCFI cluster connectivity (i.e. the number of filaments that is connected to a cluster) increases with cluster mass M200. Filament galaxies outside R200 are found to be closer to clusters at low redshift, regardless of the galaxy type. Passive galaxies in filaments are closer to clusters than star-forming galaxies in the low redshift bin alone. The passive fraction of galaxies decreases with increasing clustercentric distance up to d ∼ 5 cMpc. Galaxy groups and clusters that are not located at nodes of our reconstruction are mainly found inside cosmic filaments. Conclusions. These results give clues for pre-processing in cosmic filaments that could be due to smaller galaxy groups. This trend could be further explored by applying this method to larger photometric surveys such as the Hyper Suprime-Cam Subaru Strategic Program (HSC-SPP) or Euclid.

scholarly journals Optical and Near-Infrared Imaging of Ultra–Steep-Spectrum Radio Sources: The [ITAL]K[/ITAL]-[CLC][ITAL]z[/ITAL][/CLC] Diagram of Radio-selected and Optically Selected Galaxies

2002 ◽  
Vol 123 (2) ◽  
pp. 637-677 ◽  
Author(s):  
Carlos De Breuck ◽  
Wil van Breugel ◽  
S. A. Stanford ◽  
Huub Röttgering ◽  
George Miley ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Radio Sources ◽  
Near Infrared Imaging ◽  
Spectrum Radio

scholarly journals Planck’s dusty GEMS

2018 ◽  
Vol 620 ◽  
pp. A60 ◽  
Author(s):  
R. Cañameras ◽  
N. P. H. Nesvadba ◽  
M. Limousin ◽  
H. Dole ◽  
R. Kneissl ◽  
...  
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Infrared Imaging ◽  
High Redshift ◽  
Dust Emission ◽  
Galaxy Cluster ◽  
Star Forming ◽  
The Galaxy ◽  
Mass Outflow ◽  
Gas Accretion

We report the discovery of a molecular wind signature from a massive intensely star-forming clump of a few 109 M⊙, in the strongly gravitationally lensed submillimeter galaxy “the Emerald” (PLCK_G165.7+49.0) at z = 2.236. The Emerald is amongst the brightest high-redshift galaxies on the submillimeter sky, and was initially discovered with the Planck satellite. The system contains two magnificient structures with projected lengths of 28.5″ and 21″ formed by multiple, near-infrared arcs, falling behind a massive galaxy cluster at z = 0.35, as well as an adjacent filament that has so far escaped discovery in other wavebands. We used HST/WFC3 and CFHT optical and near-infrared imaging together with IRAM and SMA interferometry of the CO(4–3) line and 850 μm dust emission to characterize the foreground lensing mass distribution, construct a lens model with LENSTOOL, and calculate gravitational magnification factors between 20 and 50 in most of the source. The majority of the star formation takes place within two massive star-forming clumps which are marginally gravitationally bound and embedded in a 9 × 1010 M⊙, fragmented disk with 20% gas fraction. The stellar continuum morphology is much smoother and also well resolved perpendicular to the magnification axis. One of the clumps shows a pronounced blue wing in the CO(4–3) line profile, which we interpret as a wind signature. The mass outflow rates are high enough for us to suspect that the clump might become unbound within a few tens of Myr, unless the outflowing gas can be replenished by gas accretion from the surrounding disk. The velocity offset of –200 km s−1 is above the escape velocity of the clump, but not that of the galaxy overall, suggesting that much of this material might ultimately rain back onto the galaxy and contribute to fueling subsequent star formation.

scholarly journals SuperCLASS – I. The super cluster assisted shear survey: Project overview and data release 1

2020 ◽  
Vol 495 (2) ◽  
pp. 1706-1723 ◽  
Author(s):  
Richard A Battye ◽  
Michael L Brown ◽  
Caitlin M Casey ◽  
Ian Harrison ◽  
Neal J Jackson ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Near Infrared ◽  
Correlation Technique ◽  
Large Array ◽  
Photometric Redshifts ◽  
Very Large Array ◽  
Infrared Observations ◽  
Data Release ◽  
L Band ◽  
Cross Correlation Technique

ABSTRACT The SuperCLuster Assisted Shear Survey (SuperCLASS) is a legacy programme using the e-MERLIN interferometric array. The aim is to observe the sky at L-band (1.4 GHz) to a r.m.s. of $7\, \mu {\rm Jy}\,$beam−1 over an area of $\sim 1\, {\rm deg}^2$ centred on the Abell 981 supercluster. The main scientific objectives of the project are: (i) to detect the effects of weak lensing in the radio in preparation for similar measurements with the Square Kilometre Array (SKA); (ii) an extinction free census of star formation and AGN activity out to z ∼ 1. In this paper we give an overview of the project including the science goals and multiwavelength coverage before presenting the first data release. We have analysed around 400 h of e-MERLIN data allowing us to create a Data Release 1 (DR1) mosaic of $\sim 0.26\, {\rm deg}^2$ to the full depth. These observations have been supplemented with complementary radio observations from the Karl G. Jansky Very Large Array (VLA) and optical/near infrared observations taken with the Subaru, Canada-France-Hawaii, and Spitzer Telescopes. The main data product is a catalogue of 887 sources detected by the VLA, of which 395 are detected by e-MERLIN and 197 of these are resolved. We have investigated the size, flux, and spectral index properties of these sources finding them compatible with previous studies. Preliminary photometric redshifts, and an assessment of galaxy shapes measured in the radio data, combined with a radio-optical cross-correlation technique probing cosmic shear in a supercluster environment, are presented in companion papers.

scholarly journals A machine-learning approach for identifying the counterparts of submillimetre galaxies and applications to the GOODS-North field

2019 ◽  
Vol 489 (2) ◽  
pp. 1770-1786 ◽  
Author(s):  
Ruihan Henry Liu ◽  
Ryley Hill ◽  
Douglas Scott ◽  
Omar Almaini ◽  
Fangxia An ◽  
...  
Keyword(s):  
Neural Network ◽  
Machine Learning ◽  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Computational Cost ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Star Forming ◽  
Trained Neural Network ◽  
Validation Tests

ABSTRACT Identifying the counterparts of submillimetre (submm) galaxies (SMGs) in multiwavelength images is a critical step towards building accurate models of the evolution of strongly star-forming galaxies in the early Universe. However, obtaining a statistically significant sample of robust associations is very challenging due to the poor angular resolution of single-dish submm facilities. Recently, a large sample of single-dish-detected SMGs in the UKIDSS UDS field, a subset of the SCUBA-2 Cosmology Legacy Survey (S2CLS), was followed up with the Atacama Large Millimeter/submillimeter Array (ALMA), which has provided the resolution necessary for identification in optical and near-infrared images. We use this ALMA sample to develop a training set suitable for machine-learning (ML) algorithms to determine how to identify SMG counterparts in multiwavelength images, using a combination of magnitudes and other derived features. We test several ML algorithms and find that a deep neural network performs the best, accurately identifying 85 per cent of the ALMA-detected optical SMG counterparts in our cross-validation tests. When we carefully tune traditional colour-cut methods, we find that the improvement in using machine learning is modest (about 5 per cent), but importantly it comes at little additional computational cost. We apply our trained neural network to the GOODS-North field, which also has single-dish submm observations from the S2CLS and deep multiwavelength data but little high-resolution interferometric submm imaging, and we find that we are able to classify SMG counterparts for 36/67 of the single-dish submm sources. We discuss future improvements to our ML approach, including combining ML with spectral energy distribution fitting techniques and using longer wavelength data as additional features.

scholarly journals Timing the earliest quenching events with a robust sample of massive quiescent galaxies at 2 < z < 5

2020 ◽  
Vol 496 (1) ◽  
pp. 695-707 ◽  
Author(s):  
A C Carnall ◽  
S Walker ◽  
R J McLure ◽  
J S Dunlop ◽  
D J McLeod ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Selection Criteria ◽  
Spectral Energy Distribution ◽  
Photometric Data ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Star Forming ◽  
Photometric Redshift ◽  
The Times ◽  
Lower Redshift

ABSTRACT We present a sample of 151 massive (M* &gt; 1010 M⊙) quiescent galaxies at 2 &lt; z &lt; 5, based on a sophisticated Bayesian spectral energy distribution fitting analysis of the CANDELS UDS and GOODS-South fields. Our sample includes a robust sub-sample of 61 objects for which we confidently exclude low-redshift and star-forming solutions. We identify 10 robust objects at z &gt; 3, of which 2 are at z &gt; 4. We report formation redshifts, demonstrating that the oldest objects formed at z &gt; 6; however, individual ages from our photometric data have significant uncertainties, typically ∼0.5 Gyr. We demonstrate that the UVJ colours of the quiescent population evolve with redshift at z &gt; 3, becoming bluer and more similar to post-starburst galaxies at lower redshift. Based upon this, we construct a model for the time evolution of quiescent galaxy UVJ colours, concluding that the oldest objects are consistent with forming the bulk of their stellar mass at z ∼ 6–7 and quenching at z ∼ 5. We report spectroscopic redshifts for two of our objects at z = 3.440 and 3.396, which exhibit extremely weak Ly α emission in ultra-deep VANDELS spectra. We calculate star formation rates based on these line fluxes, finding that these galaxies are consistent with our quiescent selection criteria, provided their Ly α escape fractions are &gt;3 and &gt;10 per cent, respectively. We finally report that our highest redshift robust object exhibits a continuum break at λ ∼ 7000 Å in a spectrum from VUDS, consistent with our photometric redshift of $z_\mathrm{phot}=4.72^{+0.06}_{-0.04}$. If confirmed as quiescent, this object would be the highest redshift known quiescent galaxy. To obtain stronger constraints on the times of the earliest quenching events, high-SNR spectroscopy must be extended to z ≳ 3 quiescent objects.

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