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We present new [O III] 88 ${\rm \mu}$m observations of five bright $z \sim 7$ Lyman-break galaxies spectroscopically confirmed by ALMA through the [C II] 158 ${\rm \mu}$m line, unlike recent [O III] detections where Lyman-${\rm \alpha}$ was used. This nearly doubles the sample of Epoch of Reionisation galaxies with robust ($5 \sigma$) detections of [C II] and [O III]. We perform a multi-wavelength comparison with new deep HST images of the rest-frame UV, whose compact morphology aligns well with [O III] tracing ionised gas. By contrast, we find more spatially extended [C II] emission likely produced in neutral gas, as indicated by a [N II] 205 ${\rm \mu}$m non-detection in one source. We find a positive correlation between the equivalent width of the optical [O III] and H${\rm \beta}$ lines and the [O III]/[C II] ratio, as seen in local metal-poor dwarf galaxies. Cloudy models of a nebula of typical density harbouring a young stellar population with a high ionisation parameter appear to adequately reproduce the far-infrared lines. Surprisingly, however, our models fail to reproduce the strength of [O III] 88 ${\rm \mu}$m, unless we assume an ${\rm \alpha}$/Fe enhancement and a near-solar nebular oxygen abundance. On spatially resolved scales, we find [O III]/[C II] shows a tentative anti-correlation with infrared excess, $L_{\rm IR}/L_{\rm UV}$, also seen on global scales in the local Universe. Finally, we introduce the far-infrared spectral energy distribution fitting code MERCURIUS to show that dust-continuum measurements of one source appear to favour a low dust temperature coupled with a high dust mass. This implies a high stellar metallicity yield and may point towards the need of dust production or grain-growth mechanisms beyond supernovae., Comment: 23 pages, 11 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society

Cool gas (T$\sim$10$^{4}$~K) traced by hydrogen Ly$\alpha$ emission is now routinely detected around $z\sim3$ quasars, but little is known about their molecular gas reservoirs. Here, we present an APEX spectroscopic survey of the CO(6-5), CO(7-6) and [CI](2-1) emission lines for 9 quasars from the QSO MUSEUM survey which have similar UV luminosities, but very diverse Ly$\alpha$ nebulae. These observations ($\langle~\rm rms~\rangle=2.6$~mJy in 300~km~s$^{-1}$) detected three CO(6-5) lines with 3.4$\leq I_{\rm CO(6-5)} \leq$5.1~Jy~km~s$^{-1}$, 620$\leq$FWHM$\leq$707~km~s$^{-1}$, and three [CI](2-1) lines with 2.3$\leq I_{\rm [CI](2-1)} \leq$15.7~Jy~km~s$^{-1}$, 329$\leq$FWHM$\leq$943~km~s$^{-1}$. For the CO and [CI] detected sources, we constrain the molecular gas reservoirs to be $\rm M_{H_{2}} = (0.4-6.9) \times 10^{11} M_{\odot}$, while the non-detections imply $\rm M_{H_{2}} < 1.1\times 10^{11} M_{\odot}$. We compare our observations with the extended Ly$\alpha$ properties to understand the link between the cool and the molecular gas phases. We find large velocity shifts between the bulk of Ly$\alpha$ and the molecular gas systemic redshift in five sources (from $\sim$-400 to $\sim+$1200~km~s$^{-1}$). The sources with the largest shifts have the largest Ly$\alpha$ line widths in the sample, suggesting more turbulent gas conditions and/or large-scale inflows/outflows around these quasars. We also find that the brightest ($I_{\rm[CI](2-1)}=15.7\pm3.7~\rm Jy~km~s^{-1}$) and the widest (FWHM$\sim$900~km~s$^{-1}$) lines are detected for the smallest and dimmest Ly$\alpha$ nebulae. From this, we speculate that host galaxy obscuration can play an important role in reducing the ionizing and Ly$\alpha$ photons able to escape to halo scales, and/or that these systems are hosted by more massive halos., Comment: Accepted on January 3, MNRAS. 25 pages, 17 figures

Context. The Euclid mission is expected to discover thousands of z > 6 galaxies in three deep fields, which together will cover a similar to 50 deg(2) area. However, the limited number of Euclid bands (four) and the low availability of ancillary data could make the identification of z > 6 galaxies challenging., Aims. In this work we assess the degree of contamination by intermediate-redshift galaxies (z = 1-5.8) expected for z > 6 galaxies within the Euclid Deep Survey., Methods. This study is based on similar to 176 000 real galaxies at z = 1-8 in a similar to 0.7 deg(2) area selected from the UltraVISTA ultra-deep survey and similar to 96 000 mock galaxies with 25.3, Results. We demonstrate that identifying z > 6 galaxies with Euclid data alone will be very effective, with a z > 6 recovery of 91% (88%) for bright (faint) galaxies. For the UltraVISTA-like bright sample, the percentage of z = 1-5.8 contaminants amongst apparent z > 6 galaxies as observed with Euclid alone is 18%, which is reduced to 4% (13%) by including ultra-deep Rubin (Spitzer) photometry. Conversely, for the faint mock sample, the contamination fraction with Euclid alone is considerably higher at 39%, and minimised to 7% when including ultra-deep Rubin data. For UltraVISTA-like bright galaxies, we find that Euclid (I-E - Y-E) > 2:8 and (Y-E - J(E)) < 1.4 colour criteria can separate contaminants from true z > 6 galaxies, although these are applicable to only 54% of the contaminants as many have unconstrained (I-E - Y-E) colours. In the best scenario, these cuts reduce the contamination fraction to 1% whilst preserving 81% of the fiducial z > 6 sample. For the faint mock sample, colour cuts are infeasible; we find instead that a 5 sigma detection threshold requirement in at least one of the Euclid near-infrared bands reduces the contamination fraction to 25%.

Links between the properties of radio-loud active galactic nuclei (RLAGNs) and the morphology of their hosts may provide important clues for our understanding of how RLAGNs are triggered. In this work, focusing on passive galaxies, we study the shape of the hosts of RLAGNs selected from the Karl G. Jansky Very Large Array Cosmic Evolution Survey (VLA-COSMOS) 3GHz Large Project, and compare them with previous results based on the first data release (DR1) of the LOFAR Two-Metre Sky Survey (LoTSS). We find that, at redshifts of between 0.6 and 1, high-luminosity ($L_{1.4 GHz}\gtrsim10^{24}\rm W Hz^{-1}$) RLAGNs have a wider range of optical projected axis ratios than their low-redshift counterparts, which are essentially all found in round galaxies with axis ratios of higher than 0.7. We construct control samples and show that although the hosts of high-redshift RLAGNs with the highest luminosities still have a rounder shape compared with the non-RLAGNs, they on average have a smaller axis ratio (more elongated) than the local RLAGNs with similar stellar masses and radio luminosities. This evolution can be interpreted as a byproduct of radio luminosity evolution, namely that galaxies at fixed stellar mass are more radio luminous at high redshifts: artificially increasing the radio luminosities of local galaxies ($z\leq$0.3) by a factor of 2 to 4 can remove the observed evolution of the axis ratio distribution. If this interpretation is correct then the implication is that the link between AGN radio luminosity and host galaxy shape is similar at $z\simeq1$ to in the present-day Universe., Comment: 10 pages, 6 figures. Accepted by A&A

The evolution of galaxies is influenced by many physical processes which may vary depending on their environment. We combine Hubble Space Telescope (HST) and Multi-Unit Spectroscopic Explorer (MUSE) data of galaxies at 0.25, Comment: 32 pages, 29 figures, 5 tables, 7 appendices, language checked and appendix table updated (accepted for publication in A&A)

We include a fully coupled treatment of metal and dust enrichment into the Delphi semi-analytic model of galaxy formation to explain the dust content of 13 Lyman Break Galaxies (LBGs) detected by the Atacama Large millimetre Array (ALMA) REBELS Large Program at $z\simeq 7$. We find that the galaxy dust mass, $M_d$, is regulated by the combination of SNII dust production, astration, shock destruction, and ejection in outflows; grain growth (with a standard timescale $\tau_0= 30$ Myr) plays a negligible role. The model predicts a dust-to-stellar mass ratio of $\sim 0.07-0.1\%$ and a UV-to-total star formation rate relation such that $log (\psi_{\rm UV}) = -0.05 ~[log (\psi)]^{2} + 0.86 ~log(\psi) -0.05$ (implying that 55-80\% of the star formation is obscured) for REBELS galaxies with stellar mass $M_* = 10^{9-10} M_\odot$. This relation reconciles the intrinsic UV luminosity of LBGs with their observed luminosity function at $z=7$. However, 2 out of the 13 systems show dust-to-stellar mass ratios ($\sim 0.94-1.1\%$) that are up to $18\times$ larger than expected from the fiducial relation. Due to the physical coupling between dust and metal enrichment, even decreasing $\tau_0$ to very low values (0.3 Myr) only increases the dust-to-stellar mass ratio by a factor $ \sim 2$. Given that grain growth is not a viable explanation for such high observed ratios of the dust-to-stellar mass, we propose alternative solutions., Comment: Accepted to MNRAS

ALMA observations have revealed the presence of dust in the first generations of galaxies in the Universe. However, the dust temperature Td remains mostly unconstrained due to the few available FIR continuum data at redshift $z$ > 5. This introduces large uncertainties in several properties of high-$z$ galaxies, namely their dust masses, infrared luminosities, and obscured fraction of star formation. Using a new method based on simultaneous [C $\scriptstyle \rm II$] 158-μm line and underlying dust continuum measurements, we derive Td in the continuum and [C $\scriptstyle \rm II$] detected $z$ ≈ 7 galaxies in the ALMA Large Project REBELS sample. We find 39 < Td < 58 K, and dust masses in the narrow range Md = (0.9-3.6) × 107 M⊙. These results allow us to extend for the first time the reported Td($z$) relation into the Epoch of Reionization. We produce a new physical model that explains the increasing Td($z$) trend with the decrease of gas depletion time, tdep = Mg/SFR, induced by the higher cosmological accretion rate at early times; this hypothesis yields Td ∝ (1 + $z$)0.4. The model also explains the observed Td scatter at a fixed redshift. We find that dust is warmer in obscured sources, as a larger obscuration results in more efficient dust heating. For UV-transparent (obscured) galaxies, Td only depends on the gas column density (metallicity), $T_{\rm d} \propto N_{\rm H}^{1/6}$ (Td ∝ Z-1/6). REBELS galaxies are on average relatively transparent, with effective gas column densities around NH ≃ (0.03-1) × 1021 cm-2. We predict that other high-$z$ galaxies (e.g. MACS0416-Y1, A2744-YD4), with estimated Td ≫ 60 K, are significantly obscured, low-metallicity systems. In fact, Td is higher in metal-poor systems due to their smaller dust content, which for fixed LIR results in warmer temperatures.

We analyse FIR dust continuum measurements for 14 galaxies ($z\approx 7$) in the ALMA REBELS LP to derive their physical properties. Our model uses three input data: (a) the UV spectral slope, $\beta$, (b) the observed UV continuum flux at $1500$A, $F_{\rm UV}$, (c) the observed continuum flux at $\approx 158\mu$m, $F_{158}$, and considers Milky Way (MW) and SMC extinction curves, along with different dust geometries. We find that REBELS galaxies have (28-90.5)% of their star formation obscured; the total (UV+IR) star formation rates are in the range $31.5 < {\rm SFR}/ (M_\odot {\rm yr}^{-1}) < 129.5$. The sample-averaged dust mass and temperature are $(1.3\pm 1.1)\times 10^7 M_\odot$ and $52 \pm 11$ K, respectively. In some galaxies dust is abundant (REBELS-14, $M'_d \approx 3.4 \times 10^7 M_\odot$), or hot (REBELS-18, $T'_d \approx 67$ K). The dust distribution is compact ($ 1 M_\odot$. With the SFR predicted by the model and a MW extinction curve, REBELS galaxies detected in [CII] nicely follow the local $L_{\rm CII}-$SFR relation, and are approximately located on the Kennicutt-Schmidt relation. The sample-averaged gas depletion time is of $0.11\, y_P^{-2}$ Gyr, where $y_P$ is the ratio of the gas-to-stellar distribution radius. For some systems a solution simultaneously matching the observed ($\beta, F_{\rm UV}, F_{158}$) values cannot be found. This occurs when the index $I_m = (F_{158}/F_{\rm UV})/(\beta-\beta_{\rm int})$, where $\beta_{\rm int}$ is the intrinsic UV slope, exceeds $I_m^*\approx 1120$ for a MW curve. For these objects we argue that the FIR and UV emitting regions are not co-spatial, questioning the use of the IRX-$\beta$ relation., Comment: 22 pages, 7 figures, accepted by MNRAS. Comments welcome

Recent work has shown that UV-luminous reionization-era galaxies often exhibit strong Lyman-alpha emission despite being situated at redshifts where the IGM is thought to be substantially neutral. It has been argued that this enhanced Ly α transmission reflects the presence of massive galaxies in overdense regions which power large ionized bubbles. An alternative explanation is that massive galaxies shift more of their Ly α profile to large velocities (relative to the systemic redshift) where the IGM damping wing absorption is reduced. Such a mass-dependent trend is seen at lower redshifts, but whether one exists at z ∼ 7 remains unclear owing to the small number of existing systemic redshift measurements in the reionization era. This is now changing with the emergence of [C ii]-based redshifts from ALMA. Here, we report MMT/Binospec Ly α spectroscopy of eight UV-bright (MUV ∼ −22) galaxies at z ≃ 7 selected from the ALMA REBELS survey. We detect Ly α in four of eight galaxies and use the [C ii] systemic redshifts to investigate the Ly α velocity profiles. The Ly α lines are significantly redshifted from systemic (average velocity offset = 223 km s–1) and broad (FWHM ≈ 300–650 km s−1), with two sources showing emission extending to ≈750 km s−1. We find that the broadest Ly α profiles are associated with the largest [C ii] line widths, suggesting a potential link between the Ly α FWHM and the dynamical mass. Since Ly α photons at high velocities transmit efficiently through the z = 7 IGM, our data suggest that velocity profiles play a significant role in boosting the Ly α visibility of the most UV-luminous reionization-era galaxies.

We present specific star-formation rates for 40 UV-bright galaxies at $z\sim7-8$ observed as part of the Reionization Era Bright Emission Line Survey (REBELS) ALMA large program. The sSFRs are derived using improved measures of SFR and stellar masses, made possible by measurements of far-infrared (FIR) continuum emission and [CII]-based spectroscopic redshifts. For each source in the sample, we derive stellar masses from SED fitting and total SFRs from calibrations of the UV and FIR emission. The median sSFR is $18_{-5}^{+7}$ Gyr$^{-1}$, significantly larger than literature measurements lacking constraints in the FIR. The increase in sSFR reflects the larger obscured SFRs we derive from the dust continuum relative to that implied by the UV+optical SED. We suggest that such differences may reflect spatial variations in dust across these luminous galaxies, with the component dominating the FIR distinct from that dominating the UV. We demonstrate that the inferred stellar masses (and hence sSFRs) are strongly-dependent on the assumed star formation history (SFH) in reionization-era galaxies. When large sSFR galaxies are modeled with non-parametric SFHs, the derived stellar masses can increase by an order of magnitude relative to constant star formation models, owing to the presence of a significant old stellar population that is outshined by the recent burst. The [CII] line widths in the largest sSFR systems are often very broad, suggesting dynamical masses that are easily able to accommodate the dominant old stellar population suggested by non-parametric models. Regardless of these systematic uncertainties in the derived parameters, we find that the sSFR increases rapidly toward higher redshifts for massive galaxies ($9.6, 18 pages, 10 figures, submitted to MNRAS

We report the identification of radio (0.144-3 GHz), mid-IR, far-IR, and sub-mm (24-850$\mu$m) emission at the position of one of 41 UV-bright (M$_\mathrm{UV}^{}\lesssim-21.25$) $z\simeq6.6-6.9$ Lyman-break galaxy candidates in the 1.5 deg$^2$ COSMOS field. This source, COS-87259, exhibits a sharp flux discontinuity (factor $>$3) between two narrow/intermediate bands at 9450 and 9700 Angstroms and is undetected in all nine bands blueward of 9600 Angstroms, as expected from a Lyman-alpha break at $z\simeq6.8$. The full multi-wavelength (X-ray through radio) data of COS-87529 can be self-consistently explained by a very massive (M$_{\ast}=10^{10.8}$ M$_{\odot}$) and extremely red (rest-UV slope $\beta=-0.59$) $z\simeq6.8$ galaxy with hyperluminous infrared emission (L$_{\mathrm{IR}}=10^{13.6}$ L$_{\odot}$) powered by both an intense burst of highly-obscured star formation (SFR$\approx$1800 M$_{\odot}$ yr$^{-1}$) and an obscured ($\tau_{\mathrm{9.7\mu m}}=7.7\pm2.5$) radio-loud (L$_{\mathrm{1.4\ GHz}}\approx10^{25.4}$ W Hz$^{-1}$) AGN. The radio emission is compact (1.04$\pm$0.12 arcsec) and exhibits an ultra-steep spectrum between 1.32-3 GHz ($\alpha=-1.57^{+0.22}_{-0.21}$) that flattens at lower frequencies ($\alpha=-0.86^{+0.22}_{-0.16}$ between 0.144-1.32 GHz), consistent with known $z>4$ radio galaxies. We also demonstrate that COS-87259 may reside in a significant (11$\times$) galaxy overdensity at $z\simeq6.6-6.9$, as common for systems hosting radio-loud AGN. Nonetheless, a spectroscopic redshift will ultimately be required to establish the true nature of COS-87259 as we cannot yet completely rule out low-redshift solutions. If confirmed to lie at $z\simeq6.8$, the properties of COS-87259 would be consistent with a picture wherein AGN and highly-obscured star formation activity are fairly common among very massive (M$_{\ast}>10^{10}$ M$_{\odot}$) reionization-era galaxies., Comment: 14 pages, 6 figures. Accepted in MNRAS with minor revisions. This accepted version considers very recent data from LOFAR and MeerKAT which improve our analyses on the radio slope and luminosity

Agradecimentos: We thank the anonymous referee for helpful suggestions that improved the manuscript. XL thanks A. Barth, S. Dodelson, S. Gezari, and A. Palmese for comments; and B. Fields, C. Gammie, K. Gültekin, Z. Haiman, D. Lai, A. Loeb, D. D’Orazio, S. Tremaine, and X.-J. Zhu for discussions; and LCO director Tod Boroson for granting us DDT observation. W.-T. L is supported in part by the Gordon and Betty Moore Foundation’s Data-Driven Discovery Initiative through grant GBMF4561 to Matthew Turk and the government scholarship to study aboard from the ministry of education of Taiwan. YCC and XL acknowledge a Center for Advanced Study Beckman fellowship and support from the University of Illinois campus research board. YCC is supported by the government scholarship to study aboard from the ministry of education of Taiwan and the Illinois Survey Science Fellowship. AMH is supported by the DOE NNSA Stewardship Science Graduate Fellowship under grant number DE-NA0003864. YS acknowledges support from the Alfred P. Sloan Foundation and NSF grant AST-1715579. This work makes use of observations from the LCOGT network. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astroparticle Physics, Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovação, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenössische Technische Hochschule (ETH) Zürich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciències de l’Espai (IEEC/CSIC), the Institut de Física d’Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universität München and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, The Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, Texas A and M University, and the OzDES Membership Consortium. Based in part on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The DES data management system is supported by the National Science Foundation under grant numbers AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-66861, FPA2015-68048, SEV-2016-0588, SEV-2016-0597, and MDM-2015-0509, some of which include ERDF funds from the European Union. IFAE is partially funded by the CERCA program of the Generalitat de Catalunya. Research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Program (FP7/2007-2013) including ERC grant agreements 240672, 291329, and 306478. We acknowledge support from the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020, and the Brazilian Instituto Nacional de Ciênciae Tecnologia (INCT) e-Universe (CNPq grant 465376/2014-2). This manuscript has been authored by Fermi Research Alliance, LLC under contract no. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. We are grateful for the extraordinary contributions of our CTIO colleagues and the DECam Construction, Commissioning and Science Verification teams in achieving the excellent instrument and telescope conditions that have made this work possible. The success of this project also relies critically on the expertise and dedication of the DES Data Management group. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS website is www.sdss.org. SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, the French Participation Group, Harvard-Smithsonian Center for Astrophysics, Instituto de Astrofísica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Max-Planck-Institut für Astrophysik (MPA Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), National Astronomical Observatories of China, New Mexico State University, New York University, University of Notre Dame, Observatário Nacional/MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autónoma de México, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University Abstract: Binary supermassive black holes (BSBHs) are expected to be a generic byproduct from hierarchical galaxy formation. The final coalescence of BSBHs is thought to be the loudest gravitational wave (GW) siren, yet no confirmed BSBH is known in the GW-dominated regime. While periodic quasars have been proposed as BSBH candidates, the physical origin of the periodicity has been largely uncertain. Here, we report discovery of a periodicity (p = 1607 +/- 7 d) at 99.95 per cent significance (with a global p value of similar to 10(-3) accounting for the look elsewhere effect) in the optical light curves of a redshift 1.53 quasar, SDSS J025214.67-002813.7. Combining archival Sloan Digital Sky Survey data with new, sensitive imaging from the Dark Energy Survey, the total similar to 20-yr time baseline spans similar to 4.6 cycles of the observed 4.4-yr (rest frame 1.7-yr) periodicity. The light curves are best fit by a bursty model predicted by hydrodynamic simulations of circumbinary accretion discs. The periodicity is likely caused by accretion rate modulation by a milli-parsec BSBH emitting GWs, dynamically coupled to the circumbinary accretion disc. A bursty hydrodynamic variability model is statistically preferred over a smooth, sinusoidal model expected from relativistic Doppler boost, a kinematic effect proposed for PG1302-102. Furthermore, the frequency dependence of the variability amplitudes disfavours Doppler boost, lending independent support to the circumbinary accretion variability hypothesis. Given our detection rate of one BSBH candidate from circumbinary accretion variability out of 625 quasars, it suggests that future large, sensitive synoptic surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time may be able to detect hundreds to thousands of candidate BSBHs from circumbinary accretion with direct implications for Laser Interferometer Space Antenna. FINANCIADORA DE ESTUDOS E PROJETOS - FINEP FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJ CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ Fechado

Agradecimentos: We would like to thank the MNRAS anonymous referee for his/her very useful and competent report, and Micol Bolzonella for a much appreciated support with HYPERZ. This paper has also gone through internal review by the DES collaboration and we would like to thank our internal referees Karl Glazebrook and Richard McMahon for their comments that greatly improved this manuscript. We are also grateful to the DES final reader Alex Kim who gave us very useful editorial suggestions. Thanks also go to Will Hartley and Manda Banerji for providing comments, to Brian Yanny for instructing us on how to get blending information for each source, to Sophie Reed for her suggestions regarding potential mismatch between DES and VHS data, to Carlotta Gruppioni for the discussions regarding potential AGN contamination, to Benjamin Mawdsley for discussions regarding the toy model simulations predicting spurious low-z objects scattering in the selection box, and to Daniel Goddard for important stylistic plotting suggestions. We also acknowledge discussions with Alvio Renzini, Emanuele Daddi, David Elbaz, and Johan Comparat. Funding for the DES Projects has been provided by the US Department of Energy, the US National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovação, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the DES. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenössische Technische Hochschule (ETH) Zürich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciències de l'Espai (IEEC/CSIC), the Institut de Física d'Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universität München and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, The Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, Texas A&M University, and the OzDES Membership Consortium. Based in part on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The DES data management system is supported by the National Science Foundation under Grant Numbers AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-66861, FPA2015-68048, SEV-2016-0588, SEV-2016-0597, and MDM-2015-0509, some of which include ERDF funds from the European Union. IFAE is partially funded by the CERCA programme of the Generalitat de Catalunya. Research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013) including ERC grant agreements 240672, 291329, and 306478. We acknowledge support from the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020, and the Brazilian Instituto Nacional de Ciência e Tecnologia (INCT) e-Universe (CNPq grant 465376/2014-2). This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the US Department of Energy, Office of Science, Office of High Energy Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. We also ackwoledge the use of the Sciama High Performance Computer (HPC) cluster, which is supported by the ICG, SEPNet, and the University of Portsmouth, for some of our calculations Abstract: Using stellar population models, we predicted that the Dark Energy Survey (DES) - due to its special combination of area (5000 deg(2)) and depth (i = 24.3) - would be in the position to detect massive (greater than or similar to 10(11) M-circle dot) galaxies at z similar to 4. We confront those theoretical calculations with the first similar to 150 deg(2) of DES data reaching nominal depth. From a catalogue containing similar to 5 million sources, similar to 26 000 were found to have observed-frame g - r versus r - i colours within the locus predicted for z similar to 4 massive galaxies. We further removed contamination by stars and artefacts, obtaining 606 galaxies lining up by the model selection box. We obtained their photometric redshifts and physical properties by fitting model templates spanning a wide range of star formation histories, reddening and redshift. Key to constrain the models is the addition, to the optical DES bands g, r, i, z, and Y, of near-IR J, H, K-s data from the Vista Hemisphere Survey. We further applied several quality cuts to the fitting results, including goodness of fit and a unimodal redshift probability distribution. We finally select 233 candidates whose photometric redshift probability distribution function peaks around z similar to 4, have high stellar masses [log (M*/M-circle dot) similar to 11.7 for a Salpeter IMF] and ages around 0.1 Gyr, i.e. formation redshift around 5. These propertiesmatch those of the progenitors of the most massive galaxies in the local Universe. This is an ideal sample for spectroscopic follow-up to select the fraction of galaxies which are truly at high redshift. These initial results and those at the survey completion, which we shall push to higher redshifts, will set unprecedented constraints on galaxy formation, evolution, and the re-ionization epoch CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJ FINANCIADORA DE ESTUDOS E PROJETOS - FINEP Aberto

We present new HST/WFC3 observations and re-analyse VLT data to unveil the continuum, variability and rest-frame UV lines of the multiple UV clumps of the most luminous Ly$\alpha$ emitter at z=6.6, CR7. Our re-reduced, flux calibrated X-SHOOTER spectra of CR7 reveal a HeII emission line in observations obtained along the major axis of Lyman-alpha (Lya) emission with the best seeing conditions. HeII is spatially offset by +0.8'' from the peak of Lya emission, and it is found towards clump B. Our WFC3 grism spectra detects the UV continuum of CR7's clump A, yielding a power law with $\beta=-2.5^{+0.6}_{-0.7}$ and $M_{UV}=-21.87^{+0.25}_{-0.20}$. No significant variability is found for any of the UV clumps on their own, but there is tentative (~2.2$\sigma$) brightening of CR7 in F110W as a whole from 2012 to 2017. HST grism data fail to robustly detect rest-frame UV lines in any of the clumps, implying fluxes, Comment: 22 pages, 12 figures. Accepted for publication in MNRAS. Reduced data used in the paper will be available with the final published paper in MNRAS

Agradecimentos: CFW thanks the Science and Technology Facilities Council (STFC) for the award of a studentship. MB acknowledges support from STFC via an Ernest Rutherford Fellowship. PCH acknowledges support from the STFC via a Consolidated Grant to the Institute of Astronomy, Cambridge. Funding for the DES Projects has been provided by the US Department of Energy, the US National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico and the Ministerio da Ciencia, Tecnologia e Inovacao, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenossische Technische Hochschule (ETH) Zurich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciencies de l'Espai (IEEC/CSIC), the Institut de Fisica d'Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universitat Munchen and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, The Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, Texas A&M University, and the OzDES Membership Consortium. The DES data management system is supported by the National Science Foundation under Grant Number AST-1138766. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-88861, FPA2015-68048, SEV-2012-0234, SEV-2012-0249, and MDM-2015-0509, some of which include ERDF funds from the European Union. IFAE is partially funded by the CERCA program of the Generalitat de Catalunya Abstract: We present the first rest-frame UV population study of 17 heavily reddened, high-luminosity [E(B - V)(QSO) greater than or similar to 0.5||L-bol gt; 10(46) erg s(-1)] broad-line quasars at 1.5 < z < 2.7. We combine the first year of deep, optical, ground-based observations from the Dark Energy Survey (DES) with the near-infrared VISTA Hemisphere Survey and UKIDSS Large Area Survey data, from which the reddened quasars were initially identified. We demonstrate that the significant dust reddening towards the quasar in our sample allows host galaxy emission to be detected at the rest-frame UV wavelengths probed by the DES photometry. By exploiting this reddening effect, we disentangle the quasar emission from that of the host galaxy via spectral energy distribution fitting. We find evidence for a relatively unobscured, star-forming host galaxy in at least 10 quasars, with a further three quasars exhibiting emission consistent with either star formation or scattered light. From the rest-frame UV emission, we derive instantaneous, dust-corrected star formation rates (SFRs) in the range 25 < SFRUV < 365 M-circle dot yr(-1), with an average SFRUV = 130 + 95 M-circle dot yr(-1). We find a broad correlation between SFRUV and the bolometric quasar luminosity. Overall, our results show evidence for coeval star formation and black hole accretion occurring in luminous, reddened quasars at the peak epoch of galaxy formation FINANCIADORA DE ESTUDOS E PROJETOS - FINEP FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJ CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ MINISTÉRIO DA CIÊNCIA, TECNOLOGIA, INOVAÇÕES E COMUNICAÇÕES - MCTIC Aberto

We present the results of ALMA spectroscopic follow-up of a z = 6.766 Lyα emitting galaxy behind the cluster RX J1347.1-1145. We report the detection of [C II] 158 μm line fully consistent with the Lyα redshift and with the peak of the optical emission. Given the magnification of μ = 5.0 ± 0.3, the intrinsic (corrected for lensing) luminosity of the [C II] line is L [C II] = {1.4}-0.3+0.2× {10}7 {L}☉ , roughly ∼5 times fainter than other detections of z ∼ 7 galaxies. The result indicates that low L [C II] in z ∼ 7 galaxies compared to the local counterparts might be caused by their low metallicities and/or feedback. The small velocity offset ({{∆ }}v={20}-40+140 {km} {{{s}}}-1) between the Lyα and [C II] line is unusual, and may be indicative of ionizing photons escaping. These observations are based on the following ALMA data: ADS/JAO.ALMA#2015.1.00091.S. They are also associated with programs Spitzer #90009, 60034, 00083, 50610, 03550, 40593, and HST # GO10492, GO11591, GO12104, and GO13459. Furthermore based on multi-year KECK programs.

We report new deep ALMA observations aimed at investigating the [CII]158um line and continuum emission in three spectroscopically confirmed Lyman Break Galaxies at 6.8, Comment: 15 pages, 9 figures, MNRAS in press, replaced with accepted version

We present the spectroscopic confirmation of the brightest known gravitationally lensed Lyman break galaxy in the Epoch of Reionisation, A1703-zD1, through the detection of [C II] at a redshift of z = 6.8269 +/- 0.0004. This source was selected behind the strong lensing cluster Abell 1703, with an intrinsic L$_{UV}$ ~ L$^*$$_{z=7}$ luminosity and a very blue Spitzer/IRAC [3.6]-[4.5] colour, implying high equivalent width line emission of [O III]+H$\beta$. [C II] is reliably detected at 6.1$\sigma$ co-spatial with the rest-frame UV counterpart, showing similar spatial extent. Correcting for the lensing magnification, the [C II] luminosity in A1703-zD1 is broadly consistent with the local L$_{[CII]}$ - SFR relation. We find a clear velocity gradient of 103 +/- 22 km/s across the source which possibly indicates rotation or an ongoing merger. We furthermore present spectral scans with no detected [C II] above 4.6$\sigma$ in two unlensed Lyman break galaxies in the EGS-CANDELS field at z ~ 6.6 - 6.9. This is the first time that NOEMA has been successfully used to observe [C II] in a 'normal' star-forming galaxy at z > 6, and our results demonstrate its capability to complement ALMA in confirming galaxies in the Epoch of Reionisation., Comment: 9 pages, 15 figures. Accepted for publication in MNRAS