SCUBA-2 overdensities associated with candidate protoclusters selected from Planck data
T. Cheng, D. L. Clements, J. Greenslade, J. Cairns, P. Andreani, M. Bremer, L. Conversi, A. Cooray, H. Dannerbauer, G. De Zotti, S. Eales, J. González-Nuevo, E.… 展开作者
T. Cheng, D. L. Clements, J. Greenslade, J. Cairns, P. Andreani, M. Bremer, L. Conversi, A. Cooray, H. Dannerbauer, G. De Zotti, S. Eales, J. González-Nuevo, E. Ibar, L. Leeuw, J. Ma, M. J. Michałowski, H. Nayyeri, D. A. Riechers, D. Scott, P. Temi, M. Vaccari, I. Valtchanov, E. van Kampen, L. Wang
备注：
8 pages, 1 figure, 1 table, accepted for publication in MNRAS
We measure the 850-$μ$m source densities of 46 candidate protoclusters selected from the Planck High-z catalogue (PHz) and the Planck Catalogue of Compact Sources (PCCS) that were followed up with Herschel-SPIRE and SCUBA-2. This paper aims to search for overdensities of 850-$μ$m sources in order to select the fields that are most likely to be genuine protoclusters. Of the 46 candidate protoclusters, 25 have significant overdensities ($>$5 times the field counts), 11 have intermediate overdensities (3--5 times the field counts) and 10 have no overdensity ($<$3 times the field counts) of 850-$μ$m sources. We find that the enhanced number densities are unlikely to be the result of sample variance. Compared with the number counts of another sample selected from Planck's compact source catalogues, this [PHz+PCCS]-selected sample has a higher fraction of candidate protoclusters with significant overdensities, though both samples show overdensities of 850-$μ$m sources above intermediate level. Based on the estimated star-formation rate densities (SFRDs), we suggest that both samples can efficiently select protoclusters with starbursting galaxies near the redshift at which the global field SFRD peaks ($2 < z < 3$). Based on the confirmation of overdensities found here, future follow-up observations on other PHz targets may greatly increase the number of genuine DSFG-rich clusters/protoclusters.
We present SCUBA-2 850-$μ$m observations of 13 candidate starbursting protoclusters selected using Planck and Herschel data. The cumulative number counts of the 850-$μ$m sources in 9/13 of these candidate protoclusters show significant overdensities compared to the field, with the probability $<$10$^{-2}$ assuming the sources are randomly distributed in the sky. Using the 250-, 350-, 500- and 850-$μ$m flux densities, we estimate the photometric redshifts of individual SCUBA-2 sources by fitting spectral energy distribution (SED) templates with an MCMC method. The photometric redshift distribut…
We present observations at 1.1 mm towards 16 powerful radio galaxies and a radio-quiet quasar at 0.5<z<6.3 acquired with the AzTEC camera mounted at the JCMT and ASTE to study the spatial distribution of submillimeter galaxies towards possible protocluster regions. The survey covers a total area of 1.01 square degrees with rms depths of 0.52 - 1.44 mJy and detects 728 sources above 3sigma. We find overdensities of a factor of ~2 in the source counts of 3 individual fields (4C+23.56, PKS1138-262 and MRC0355-037) over areas of ~200 sq deg. When combining all fields, the source-count analysis fin…
We have developed a search methodology to identify galaxy protoclusters at $z>2.74$, and implemented it on a sample of $\sim$14,000 galaxies with previously measured redshifts. The results of this search are recorded in the Candidate Cluster and Protocluster Catalog (CCPC). The catalog contains 12 clusters that are highly significant overdensities ($δ_{gal}>7$), 6 of which are previously known. We also identify another 31 candidate protoclusters (including 4 previously identified structures) of lower overdensity. CCPC systems vary over a wide range of physical sizes and shapes, from small, com…
We present a Herschel/SPIRE survey of three protoclusters at z=2-3 (2QZCluster, HS1700, SSA22). Based on the SPIRE colours (S350/S250 and S500/S350) of 250 $μ$m sources, we selected high redshift dusty star-forming galaxies potentially associated with the protoclusters. In the 2QZCluster field, we found a 4-sigma overdensity of six SPIRE sources around 4.5' (~2.2 Mpc) from a density peak of H$α$ emitters at z=2.2. In the HS1700 field, we found a 5-sigma overdensity of eight SPIRE sources around 2.1' (~1.0 Mpc) from a density peak of LBGs at z=2.3. We did not find any significant overdensities …
We carried out deep H$α$ narrowband imaging with 10 hours net integrations towards the young protocluster, USS1558$-$003 at $z=2.53$ with the Subaru Telescope. This system is composed of four dense groups with massive local overdensities, traced by 107 H$α$ emitters (HAEs) with stellar masses and dust-corrected star formation rates down to $1\times10^8$ M$_\odot$ and 3 M$_\odot$yr$^{-1}$, respectively. We have investigated the environmental dependence of various physical properties within the protocluster by comparing distributions of HAEs in higher and lower densities with a standard Kolmogor…
We conduct a systematic search for protocluster candidates at $z \geq 6$ in the COSMOS field using the recently released COSMOS2020 source catalog. We select galaxies using a number of selection criteria to obtain a sample of galaxies that have a high probability of being inside a given redshift bin. We then apply overdensity analysis to the bins using two density estimators, a Weighted Adaptive Kernel Estimator and a Weighted Voronoi Tessellation Estimator. We have found 15 significant ($>4σ$) candidate galaxy overdensities across the redshift range $6\le z\le7.7$. The majority of the galaxie…
We present SCUBA-2 follow-up of 61 candidate high-redshift Planck sources. Of these, 10 are confirmed strong gravitational lenses and comprise some of the brightest such submm sources on the observed sky, while 51 are candidate proto-cluster fields undergoing massive starburst events. With the accompanying Herschel-SPIRE observations and assuming an empirical dust temperature prior of $34^{+13}_{-9}$ K, we provide photometric redshift and far-IR luminosity estimates for 172 SCUBA-2-selected sources within these Planck overdensity fields. The redshift distribution of the sources peak between a …
We present a detailed study of Near-IR selected galaxies in a protocluster field at z = 3.13. Protocluster galaxies are selected using the available mutliwavelength data with the photometric redshift (photo-z) at 2.9 < z < 3.3, reaching a mass completeness of ~10^10 M_sun. Diverse types of galaxies have been found in the field including normal star-forming galaxies, quiescent galaxies and dusty star-forming galaxies. The photo-z galaxies form two large overdense structures in the field, largely overlapping with the previously identified galaxy overdensities traced by Lyα emitters (LAEs) and Ly…
We investigate extremely luminous dusty galaxies in the environments around WISE-selected hot dust obscured galaxies (Hot DOGs) and WISE/radio-selected active galactic nuclei (AGNs) at average redshifts of z = 2.7 and z = 1.7, respectively. Previous observations have detected overdensities of companion submillimetre-selected sources around 10 Hot DOGs and 30 WISE/radio AGNs, with overdensities of ~ 2 - 3 and ~ 5 - 6 , respectively. We find that the space densities in both samples to be overdense compared to normal star-forming galaxies and submillimetre galaxies (SMGs) in the SCUBA-2 Cosmology…
We present James Clerk Maxwell Telescope Submillimetre Common-User Bolometer Array 2 (SCUBA-2) 850 & 450 $μ$m observations ($σ_{850}\sim0.5$ mJy, $σ_{450}\sim5$ mJy) of the HS1549+19 and HS1700+64 survey fields containing two of the largest known galaxy over-densities at $z=2.85$ and $2.30$, respectively. We detect 56 sub-millimetre galaxies (SMGs) with SNR $> 4$ over $\sim 50$ arcmin$^2$ at 850 $μ$m with flux densities of 3 - 17 mJy. The number counts indicate over-densities in the $3$-arcmin diameter core region ($\sim 1.5$ Mpc at $z=2.5$) of $6^{+4}_{-2}\times$ (HS1549) and $4^{+6}_{-2}\tim…
The Candidate Cluster and Protocluster Catalog (CCPC) is a list of objects at redshifts z > 2 composed of galaxies with spectroscopically confirmed redshifts that are coincident on the sky and in redshift. These protoclusters are identified by searching for groups in volumes corresponding to the expected size of the most massive protoclusters at these redshifts. In CCPC1 we identified 43 candidate protoclusters among 14,000 galaxies between 2.74 < z < 3.71. Here we expand our search to more than 40,000 galaxies with spectroscopic redshifts z > 2.00, resulting in an additional 173 candidate str…
The Planck list of high-redshift source candidates (the PHz catalogue) contains 2151 peaks in the cosmic infrared background, unresolved by Planck's 5 arcmin beam. Follow-up spectroscopic observations have revealed that some of these objects are $z \approx 2$ protoclusters and strong gravitational lenses, but an unbiased survey has not yet been carried out. To this end, we have used archival Herschel-SPIRE observations to study a uniformly-selected sample of 187 PHz sources. In contrast with follow-up studies that were biased towards bright, compact sources, we find that only one of our PHz so…
The Candidate Cluster and Protocluster Catalog (CCPC) contains 218 galaxy overdensities com- posed of more than 2000 galaxies with spectroscopic redshifts spanning the first few Gyrs after the Big Bang (2.0 < z < 6.6). We use Spitzer archival data to track the underlying stellar mass of these overdense regions in various temporal cross sections by building rest-frame near-infrared luminosity functions across the span of redshifts.This exercise maps the stellar growth of protocluster galaxies, as halos in the densest environments should be the most massive from hierarchical accretion. The chara…
We present SCUBA-2 and SMA follow-up observations of four candidate high redshift Dusty Star-Forming Galaxies, selected as sources with rising SEDs in the 250, 350 and 500$μ$m Herschel SPIRE bands. Previous SMA observations showed no counterparts to these sources, but in our deeper sub-mm observations we detect counterparts to all four 500$μ$m risers, with three resolving into multiple systems. For these three multiple systems, the SMA 345GHz ($\approx 870μ$m) observations recover $123 \pm 73\%$, $60 \pm 15\%$ and $19 \pm 4\%$ respectively of the integrated 850$μ$m flux density from SCUBA-2, i…
JCMT/SCUBA-2 uncovers an excess of $850μ$m counts on megaparsec scales around high-redshift quasars. Characterization of the overdensities and their alignment with the quasars' Ly$α$ nebulae
We present spectroscopic confirmation of two new massive galaxy protoclusters at $z=2.24\pm0.02$, BOSS1244 and BOSS1542, traced by groups of Coherently Strong Ly$α$ Absorption (CoSLA) systems imprinted in the absorption spectra of a number of quasars from the SDSS III and identified as overdensities of narrowband-selected H$α$ emitters (HAEs). Using MMT/MMIRS and LBT/LUCI near-infrared (NIR) spectroscopy, we confirm 46 and 36 HAEs in the BOSS1244 and BOSS1542 fields, respectively. BOSS1244 displays a South-West (SW) component at $z=2.230\pm0.002$ and another North-East (NE) component at $z=2.2…
We present new observations of the field containing the z=3.786 protocluster, PC217.96+32.3. We confirm that it is one of the largest and most overdense high-redshift structures known. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1.2x0.6 deg area (~150x75 comoving Mpc) surrounding the protocluster's core and discovered 165 candidate Lyman Alpha emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least 2 overdense regions traced by the LAEs, the largest of which shows an areal overd…
We report fourteen and twenty-eight protocluster candidates at z=5.7 and 6.6 over 14 and 19 deg^2 areas, respectively, selected from 2,230 (259) Lya emitters (LAEs) photometrically (spectroscopically) identified with Subaru/Hyper Suprime-Cam (HSC) deep images (Keck, Subaru, and Magellan spectra and the literature data). Six out of the 42 protocluster candidates include 1-12 spectroscopically confirmed LAEs at redshifts up to z=6.574. By the comparisons with the cosmological Lya radiative transfer (RT) model reproducing LAEs with the reionization effects, we find that more than a half of these …
Bright Ly-$α$ blobs (LABs) --- extended nebulae with sizes of $\sim$100kpc and Ly-$α$ luminosities of $\sim$10$^{44}$erg s$^{-1}$ --- often reside in overdensities of compact Ly-$α$ emitters (LAEs) that may be galaxy protoclusters. The number density, variance, and internal kinematics of LABs suggest that they themselves trace group-like halos. Here we test this hierarchical picture, presenting deep, wide-field Ly-$α$ narrowband imaging of a 1$^\circ$ $\times$ 0.5$^\circ$ region around a LAB pair at $z$ = 2.3 discovered previously by a blind survey. We find 183 Ly-$α$ emitters, including the o…
We investigate the region around the Planck-detected z=3.26 gravitationally lensed galaxy HATLAS J114637.9-001132 (hereinafter HATLAS12-00) using both archival Herschel data from the H-ATLAS survey and using submm data obtained with both LABOCA and SCUBA2. The lensed source is found to be surrounded by a strong overdensity of both Herschel-SPIRE sources and submm sources. We detect 17 bright (S_870 >~7 mJy) sources at >4sigma closer than 5 arcmin to the lensed object at 850/870 microns. Ten of these sources have good cross-identifications with objects detected by Herschel-SPIRE which have redd…
Bright high-redshift quasars ($z>6$), hosting supermassive black holes ($\rm M_{BH} > 10^8 M_{\odot}$), are expected to reside in massive host galaxies embedded within some of the earliest and most massive galaxy overdensities. We analyze 1.2\,mm ALMA dust continuum maps of 35 bright quasars at $6<z<7$ and search the primary beam for excess dust continuum emission from sources with L$_{\rm IR} \gtrsim{ 10^{12}}$\,L$_{\odot}$ as evidence for early protoclusters. We compare the detection rates of continuum sources at $\geq5σ$ significance in the fields surrounding the quasars (A$_{\rm eff}$ = 4.…
ODIN: Confirmation and 3D Reconstruction of Six Massive Protoclusters at Cosmic Noon
Purdue University（普渡大学）；NSF NOIRLab（美国国家光学-红外天文研究实验室）；Arizona State University（亚利桑那州立大学）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Boston University（波士顿大学）；Universidad Andres Bello（安德烈斯贝略大学）；Università degli Studi di Milano（米兰大学）；INAF-Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）
Identifying a protocluster formation at z $\sim$ 4.5 in the COSMOS field: an extension of Taralay protocluster, traced by Ly-alpha emitters surrounding a submm galaxy
The MAMMOTH-Grism slitless spectroscopic survey is a Hubble Space Telescope (HST) cycle-28 medium program, which is obtaining 45 orbits of WFC3/IR grism spectroscopy in the density peak regions of three massive galaxy protoclusters at $z=2-3$ discovered using the MAMMOTH technique. We introduce this survey by presenting the first measurement of the mass-metallicity relation (MZR) at high redshift in overdense environments via grism spectroscopy. From the completed MAMMOTH-Grism observations in the field of the BOSS1244 protocluster at $z=2.24\pm0.02$, We secure a sample of 36 protocluster memb…
About 2100 star-forming galaxy protocluster candidates at z=1-4 were identified at sub-mm wavelengths in the Planck all sky survey. Follow-up spectroscopic observations of a few candidates have confirmed the presence of actual galaxy overdensities with large star-formation rates. In this work, we use state-of-the-art hydrodynamical simulations to investigate whether the Planck high-z sub-mm sources are progenitors of massive clusters at z=0. To match the PHz sources with simulated halos, we select the most star-forming halos from z = 3 to z =1.3 in the TNG300 simulation. The total star formati…
A cosmic collision in the making: JWST/NIRISS reveals a merging and maturing protocluster core at z~3 around a red quasar
Zentrum für Astronomie der Universität Heidelberg, Astronomisches Rechen-Institut（海德堡大学天文学中心，天文计算研究所）；Space Telescope Science Institute（太空望远镜科学研究所）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；Department of Physics, Rhodes College（罗德学院物理系）；Department of Physics and Astronomy, Bloomberg Center, Johns Hopkins University（约翰斯·霍普金斯大学彭博中心物理与天文学系）；Institute for Advanced Study（高等研究院）；Department of Astronomy and Joint Space-Science Institute, University of Maryland, College Park（马里兰大学帕克分校天文学系及联合空间科学研究所）；Departamento de Astronomia, Instituto de Física, Universidade Federal do Rio Grande do Sul（南里奥格兰德联邦大学物理研究所天文学系）
Too many protoclusters? Reconciling the overabundance of cluster progenitors within the first billion years of the Universe
University of Geneva（日内瓦大学）；University of Nottingham（诺丁汉大学）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）；Kavli Institute for Cosmology, University of Cambridge（剑桥大学卡弗里宇宙学研究所）；Cavendish Laboratory, University of Cambridge（剑桥大学卡文迪许实验室）；The Pennsylvania State University（宾夕法尼亚州立大学）；DTU Space, Technical University of Denmark（丹麦技术大学空间研究所）
We present SCUBA-2 850um submillimetre (submm) observations of the fields of 10 dusty, luminous galaxies at z ~ 1.7 - 4.6, detected at 12um and/or 22um by the WISE all-sky survey, but faint or undetected at 3.4um and 4.6um; dubbed hot, dust-obscured galaxies (Hot DOGs). The six detected targets all have total infrared luminosities greater than 10^13 L_sun, with one greater than 10^14 L_sun. Their spectral energy distributions (SEDs) are very blue from mid-infrared to submm wavelengths and not well fitted by standard AGN SED templates, without adding extra dust extinction to fit the WISE 3.4um …
Using moderate-resolution optical spectra from 58 background Lyman-break galaxies and quasars at $z\sim 2.3-3$ within a $11.5'\times13.5'$ area of the COSMOS field ($\sim 1200\,\mathrm{deg}^2$ projected area density or $\sim 2.4\,h^{-1}\,\mathrm{Mpc}$ mean transverse separation), we reconstruct a 3D tomographic map of the foreground Ly$α$ forest absorption at $2.2<z<2.5$ with an effective smoothing scale of $σ_{3d}\approx3.5\,h^{-1}\,\mathrm{Mpc}$ comoving. Comparing with 61 coeval galaxies with spectroscopic redshifts in the same volume, we find that the galaxy positions are clearly biased to…
The RAdio Galaxy Environment Reference Survey (RAGERS): Evidence of an anisotropic distribution of submillimeter galaxies in the 4C 23.56 protocluster at z=2.48
Do Submillimeter Galaxies Trace Megaparsec Large-scale Structures? -- An Overdensity Analysis of 449 Submillimeter Galaxies in COSMOS
Purple Mountain Observatory, Chinese Academy of Science（中国科学院紫金山天文台）；School of Astronomy and Space Sciences, University of Science and Technology of China（中国科学技术大学天文与空间科学学院）；State Key Laboratory of Radio Astronomy and Technology, Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台射电天文与技术重点实验室）；Instituto de Astrofísica de Canarias (IAC)（加那利天体物理研究所）；Universidad de La Laguna（拉古纳大学）；INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所博洛尼亚空间科学观测站）；INAF-Osservatorio Astronomico di Capodimonte（意大利国家天体物理研究所卡波迪蒙特天文台）；Dipartimento di Fisica e Astronomia “A. Righi”, Alma Mater Studiorum Università di Bologna（博洛尼亚大学阿玛·玛特·斯图迪奥鲁姆物理与天文学“A. Righi”系）
We report the discovery of a large-scale structure containing multiple protoclusters at z=3.78 in the Boötes field. The spectroscopic discovery of five galaxies at z=3.783+/-0.002 lying within 1 Mpc of one another led us to undertake a deep narrow- and broad-band imaging survey of the surrounding field. Within a comoving volume of 72x72x25 Mpc^3, we have identified 65 Lyman alpha emitter (LAE) candidates at z=3.795+/-0.015, and four additional galaxies at z_spec=3.730,3.753,3.780,3.835. The galaxy distribution within the field is highly non-uniform, exhibiting three large (~3-5x) overdensities…
In the hierarchical model of structure formation, giant elliptical galaxies form through merging processes within the highest density peaks known as protoclusters. While high-redshift radio galaxies usually pinpoint the location of these environments, we have recently discovered at z~2-3 three Enormous (>200 kpc) Lyman-Alpha Nebulae (ELANe) that host multiple AGN and that are surrounded by overdensities of Lyman-alpha Emitters (LAE). These regions are prime candidates of massive protoclusters in the early stages of assembly. To characterize the star-forming activity within these rare structure…
We report the first spatially resolved measurements of gas-phase metallicity radial gradients in star-forming galaxies in overdense environments at $z\gtrsim2$. The spectroscopic data are acquired by the \mg\ survey, a Hubble Space Telescope (HST) cycle-28 medium program. This program is obtaining 45 orbits of WFC3/IR grism spectroscopy in the density peak regions of three massive galaxy protoclusters (BOSS 1244, BOSS 1542 and BOSS 1441) at $z=2-3$. Our sample in the BOSS 1244 field consists of 20 galaxies with stellar-mass ranging from $10^{9.0}$ to $10^{10.3}$ \Msun\ , star formation rate (S…
Galaxy clusters at high redshift are key targets for understanding matter assembly in the early Universe, yet they are challenging to locate. A sample of >2000 high-z candidate structures has been found using Planck's all-sky submm maps, and a sub-set of 234 have been followed up with Herschel-SPIRE, which showed that the emission can be attributed to large overdensities of dusty star-forming galaxies. In order to resolve and characterise the individual galaxies we targeted the eight brightest SPIRE sources in the centre of the Planck peak PLCK G073.4-57.5 using ALMA at 1.3 mm, and complemente…
Euclid Quick Data Release (Q1). The first Euclid view of Planck galaxy protocluster candidates at cosmic noon
Université Paris-Saclay（巴黎萨克雷大学）；CNRS（法国国家科学研究中心）；Institut d’astrophysique spatiale（空间天体物理研究所）；Centre National d’Etudes Spatiales (CNES)（法国国家空间研究中心）；Institut de Recherche en Informatique de Toulouse (IRIT)（图卢兹计算机研究所）；Université de Toulouse（图卢兹大学）；Laboratoire MCD, Centre de Biologie Intégrative (CBI)（MCD实验室，综合生物学中心）；INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（博洛尼亚天文物理与空间科学研究所）；Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）；Departamento de Astrofísica, Universidad de La Laguna (ULL)（拉帕尔马大学天体物理学系）；Université Paris Cité（巴黎西岱大学）；Astroparticule et Cosmologie（粒子天体物理学与宇宙学实验室）；CNRS-UCB International Research Laboratory, Centre Pierre Binetruy, IRL2007, CPB-IN2P3, Berkeley（CNRS-加州大学伯克利分校国际研究实验室，皮埃尔·比内特鲁中心）；Laboratoire d’etude de l’Univers et des phenomenes eXtremes, Observatoire de Paris, Université PSL, Sorbonne Université（极端宇宙现象研究实验室，巴黎天文台，PSL大学，索邦大学）
Faint star-forming galaxies at $z\sim 2-3$ can be used as alternative background sources to probe the Lyman-$α$ forest in addition to quasars, yielding high sightline densities that enable 3D tomographic reconstruction of the foreground absorption field. Here, we present the first data release from the COSMOS Lyman-Alpha Mapping And Mapping Observations (CLAMATO) Survey, which was conducted with the LRIS spectrograph on the Keck-I telescope. Over an observational footprint of 0.157$\mathrm{deg}^2$ within the COSMOS field, we used 240 galaxies and quasars at $2.17<z<3.00$, with a mean comoving …
We present the largest-ever sample of 79 Ly$α$ emitters (LAEs) at $z\sim$ 7.0 selected in the COSMOS and CDFS fields of the LAGER project (the Lyman Alpha Galaxies in the Epoch of Reionization). Our newly amassed ultradeep narrowband exposure and deeper/wider broadband images have more than doubled the number of LAEs in COSMOS, and we have selected 30 LAEs in the second field CDFS. We detect two large-scale LAE-overdense regions in the COSMOS that are likely protoclusters at the highest redshift to date. We perform injection and recovery simulations to derive the sample incompleteness. We show…
[Abridged] We use the Planck all-sky submm and mm maps to search for rare sources distinguished by extreme brightness, a few hundreds of mJy, and their potential for being situated at high redshift. These "cold" Planck sources, selected using the High Frequency Instrument (HFI) directly from the maps and from the Planck Catalogue of Compact Sources (PCCS), all satisfy the criterion of having their rest-frame far-infrared peak redshifted to the frequency range 353 and 857 GHz. This colour-selection favours galaxies in the redshift range z=2-4, which we consider as cold peaks in the cosmic infra…
