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1. SCUBA-2 observations of candidate starbursting protoclusters selected by Planck and Herschel-SPIRE

   https://doi.org/10.1093/mnras/stz2640  

   Cheng, T. ; Clements, D. L. ; Greenslade, J. ; Cairns, J. ; Andreani, P. ; Bremer, M. ; Conversi, L. ; Cooray, A. ; Dannerbauer, H. ; De Zotti, G. ; et al ( September 2019 , Monthly Notices of the Royal Astronomical Society)

   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 <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 < z < 3, is consistent with that ofmore »known z > 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.

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2. Overdensities of submillimetre-bright sources around candidate protocluster cores selected from the South Pole Telescope survey

   https://doi.org/10.1093/mnras/stab2800  

   Wang, George C ; Hill, Ryley ; Chapman, S C ; Weiß, A ; Scott, Douglas ; Apostolovski, Yordanka ; Aravena, Manuel ; Archipley, Melanie Ann ; Béthermin, Matthieu ; Canning, R E ; et al ( October 2021 , Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We present APEX-LABOCA 870-μm observations of the fields surrounding the nine brightest high-redshift unlensed objects discovered in the South Pole Telescope’s (SPT) 2500 deg2 survey. Initially seen as point sources by SPT’s 1-arcmin beam, the 19-arcsec resolution of our new data enables us to deblend these objects and search for submillimetre (submm) sources in the surrounding fields. We find a total of 98 sources above a threshold of 3.7σ in the observed area of 1300 arcmin2, where the bright central cores resolve into multiple components. After applying a radial cut to our LABOCA sources to achieve uniform sensitivity and angular sizemore »across each of the nine fields, we compute the cumulative and differential number counts and compare them to estimates of the background, finding a significant overdensity of $\delta \, {\approx }\,$10 at $S_{870}= 14$ mJy. The large overdensities of bright submm sources surrounding these fields suggest that they could be candidate protoclusters undergoing massive star formation events. Photometric and spectroscopic redshifts of the unlensed central objects range from $z= $3 to 7, implying a volume density of star-forming protoclusters of approximately 0.1 Gpc−3. If the surrounding submm sources in these fields are at the same redshifts as the central objects, then the total star formation rates of these candidate protoclusters reach 10 000 M⊙ yr−1, making them much more active at these redshifts than seen so far in either simulations or observations.« less
3. First Data Release of the COSMOS LyA Mapping and Tomography Observations: 3D LyA Forest Tomography at 2.05

   https://doi.org/https://doi.org/10.3847/1538-4365/aace58  

   Lee, KG ; Krolewski, A ; White, M ; Schlegel, D ; Nugent, P ; Hennawi, J ( October 2018 , Astrophysical journal. Supplement series)

   Faint star-forming galaxies at z∼2–3 can be used as alternative background sources to probe the Lyα 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 Lyα Mapping And Tomography Observations (CLAMATO) Survey, which was conducted with the LRIS spectrograph on the Keck I telescope. Over an observational footprint of 0.157 deg2 within the COSMOS field, we used 240 galaxies and quasars at 2.17<z<3.00, with a mean comoving transverse separation of 2.37 h-1 Mpc, as background sources probing the foreground Lyαmore »forest absorption at 2.05<z<2.55. The Lyα forest data was then used to create a Wiener- filtered tomographic reconstruction over a comoving volume of 3.15 ́ 105 h-3 Mpc3 with an effective smoothing scale of 2.5 h-1 Mpc. In addition to traditional figures, this map is also presented as a virtual-reality visualization and manipulable interactive figure. We see large overdensities and underdensities that visually agree with the distribution of coeval galaxies from spectroscopic redshift surveys in the same field, including overdensities associated with several recently discovered galaxy protoclusters in the volume. Quantitatively, the map signal-to- noise is S Nwiener » 3.4 over a 3 h−1Mpc top-hat kernel based on the variances estimated from the Wiener filter. This data release includes the redshift catalog, reduced spectra, extracted Lyα forest pixel data, and reconstructed tomographic map of the absorption. These can be downloaded from Zenodo« less
4. The ALPINE–ALMA [C II] survey: Luminosity function of serendipitous [C II] line emitters at z ∼ 5

   https://doi.org/10.1051/0004-6361/202038607  

   Loiacono, Federica ; Decarli, Roberto ; Gruppioni, Carlotta ; Talia, Margherita ; Cimatti, Andrea ; Zamorani, Gianni ; Pozzi, Francesca ; Yan, Lin ; Lemaux, Brian C. ; Riechers, Dominik A. ; et al ( February 2021 , Astronomy & Astrophysics)

   We present the first [C II] 158 μ m luminosity function (LF) at z  ∼ 5 from a sample of serendipitous lines detected in the ALMA Large Program to INvestigate [C II] at Early times (ALPINE). A study of the 118 ALPINE pointings revealed several serendipitous lines. Based on their fidelity, we selected 14 lines for the final catalog. According to the redshift of their counterparts, we identified eight out of 14 detections as [C II] lines at z  ∼ 5, along with two as CO transitions at lower redshifts. The remaining four lines have an elusive identification in the available catalogsmore »and we considered them as [C II] candidates. We used the eight confirmed [C II] and the four [C II] candidates to build one of the first [C II] LFs at z  ∼ 5. We found that 11 out of these 12 sources have a redshift very similar to that of the ALPINE target in the same pointing, suggesting the presence of overdensities around the targets. Therefore, we split the sample in two (a “clustered” and “field” subsample) according to their redshift separation and built two separate LFs. Our estimates suggest that there could be an evolution of the [C II] LF between z  ∼ 5 and z  ∼ 0. By converting the [C II] luminosity to the star-formation rate, we evaluated the cosmic star-formation rate density (SFRD) at z  ∼ 5. The clustered sample results in a SFRD ∼10 times higher than previous measurements from UV–selected galaxies. On the other hand, from the field sample (likely representing the average galaxy population), we derived a SFRD ∼1.6 higher compared to current estimates from UV surveys but compatible within the errors. Because of the large uncertainties, observations of larger samples will be necessary to better constrain the SFRD at z  ∼ 5. This study represents one of the first efforts aimed at characterizing the demography of [C II] emitters at z  ∼ 5 using a mm selection of galaxies.« less
5. The MeerKAT Galaxy Cluster Legacy Survey: I. Survey Overview and Highlights

   https://doi.org/10.1051/0004-6361/202141488  

   Knowles, K. ; Cotton, W. D. ; Rudnick, L. ; Camilo, F. ; Goedhart, S. ; Deane, R. ; Ramatsoku, M. ; Bietenholz, M. F. ; Brüggen, M. ; Button, C. ; et al ( January 2022 , Astronomy & Astrophysics)

   MeerKAT’s large number (64) of 13.5 m diameter antennas, spanning 8 km with a densely packed 1 km core, create a powerful instrument for wide-area surveys, with high sensitivity over a wide range of angular scales. The MeerKAT Galaxy Cluster Legacy Survey (MGCLS) is a programme of long-track MeerKAT L -band (900−1670 MHz) observations of 115 galaxy clusters, observed for ∼6−10 h each in full polarisation. The first legacy product data release (DR1), made available with this paper, includes the MeerKAT visibilities, basic image cubes at ∼8″ resolution, and enhanced spectral and polarisation image cubes at ∼8″ and 15″ resolutions.more »Typical sensitivities for the full-resolution MGCLS image products range from ∼3−5 μJy beam −1 . The basic cubes are full-field and span 2° × 2°. The enhanced products consist of the inner 1.2° × 1.2° field of view, corrected for the primary beam. The survey is fully sensitive to structures up to ∼10′ scales, and the wide bandwidth allows spectral and Faraday rotation mapping. Relatively narrow frequency channels (209 kHz) are also used to provide H  I mapping in windows of 0 <  z  < 0.09 and 0.19 <  z  < 0.48. In this paper, we provide an overview of the survey and the DR1 products, including caveats for usage. We present some initial results from the survey, both for their intrinsic scientific value and to highlight the capabilities for further exploration with these data. These include a primary-beam-corrected compact source catalogue of ∼626 000 sources for the full survey and an optical and infrared cross-matched catalogue for compact sources in the primary-beam-corrected areas of Abell 209 and Abell S295. We examine dust unbiased star-formation rates as a function of cluster-centric radius in Abell 209, extending out to 3.5 R 200 . We find no dependence of the star-formation rate on distance from the cluster centre, and we observe a small excess of the radio-to-100 μm flux ratio towards the centre of Abell 209 that may reflect a ram pressure enhancement in the denser environment. We detect diffuse cluster radio emission in 62 of the surveyed systems and present a catalogue of the 99 diffuse cluster emission structures, of which 56 are new. These include mini-halos, halos, relics, and other diffuse structures for which no suitable characterisation currently exists. We highlight some of the radio galaxies that challenge current paradigms, such as trident-shaped structures, jets that remain well collimated far beyond their bending radius, and filamentary features linked to radio galaxies that likely illuminate magnetic flux tubes in the intracluster medium. We also present early results from the H  I analysis of four clusters, which show a wide variety of H  I mass distributions that reflect both sensitivity and intrinsic cluster effects, and the serendipitous discovery of a group in the foreground of Abell 3365.« less