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We use deep, spatially resolved spectroscopy from the Large Early Galaxy Astrophysics Census Survey to study radial variations in the stellar population of 17 spectroscopically selected post-starburst (PSB) galaxies. We use spectral fitting to measure two Lick indices, H δA and Fe 4383 , and find that, on average, PSB galaxies have radially decreasing H δA and increasing Fe 4383  profiles. In contrast, a control sample of quiescent, non-PSB galaxies in the same mass range shows outwardly increasing H δA and decreasing Fe 4383 . The observed gradients are weak (≈−0.2 Å/ R e), mainly due to seeing convolution. A two-SSP (simple stellar population) model suggests that intrinsic gradients are as strong as observed in local PSB galaxies (≈−0.8 Å/ R e). We interpret these results in terms of inside-out growth (for the bulk of the quiescent population) versus star formation occurring last in the centre (for PSB galaxies). At z ≈ 0.8, central starbursts are often the result of gas-rich mergers, as evidenced by the high fraction of PSB galaxies with disturbed morphologies and tidal features (40 per cent). Our results provide additional evidence for multiple paths to quiescence: a standard path, associated with inside-out disc formation and with gradually decreasing star formation activity, without fundamental structural transformation, and a fast path, associated with centrally concentrated starbursts, leaving an inverse age gradient and smaller half-light radius. [ABSTRACT FROM AUTHOR]

Distant luminous Lyman-α emitters are excellent targets for detailed observations of galaxies in the epoch of reionisation. Spatially resolved observations of these galaxies allow us to simultaneously probe the emission from young stars, partially ionised gas in the interstellar medium and to constrain the properties of the surrounding hydrogen in the circumgalactic medium. We review recent results from (spectroscopic) follow-up studies of the rest-frame UV, Lyman-α and [CII] emission in luminous galaxies observed ∼500 Myr after the Big Bang with ALMA, HST/WFC3 and VLT/X-SHOOTER. These galaxies likely reside in early ionised bubbles and are complex systems, consisting of multiple well separated and resolved components where traces of metals are already present. [ABSTRACT FROM AUTHOR]

We leverage new ultra-deep, high resolution, multi-frequency radio imaging at 6 and 3 GHz with the unique datasets available in the GOODS-S/HUDF region in order to assess the AGN fraction in a faint radio-selected sample. For AGN identification, we adopt a multi-wavelength approach, combining X-ray and (mid-)infrared (IR) selections with radio identification such as X-ray to radio excess, flat radio spectral slopes, and the radio-IR correlation. We identify AGN in 43% of our radio sample, yielding an AGN source density of ∼ 1 arcmin−2. This AGN fraction is likely underestimated, as 1) our shallower 3 GHz data is biased against flat radio spectrum sources and 2) all of our selections may be biased against the most heavily obscured AGN. The James Webb Space Telescope's Mid-Infrared Instrument (MIRI) will address the latter issue and we briefly outline our Cycle 1 Guaranteed Time Observation (GTO) program to search for heavily obscured AGN. [ABSTRACT FROM AUTHOR]

Several scenarios have been proposed to describe the physical connection between galaxies and their central active galactic nuclei (AGN). This connection could act on a range of spatial scales and vary across cosmic time. In these proceedings, we consider black hole and galaxy growth and whether that growth is affected by AGN feedback both based on statistical approaches – which reveal general population trends – and based on an individual case study – which gives us a more detailed insight on the physical processes at play. For the statistical approach, we showcase a low-redshift (0.04 < z < 0.2) SDSS sample with AGN classification based on a combination of emission-line diagnostic diagrams, and for which we account for sample selection by using a V/Vmax approach. The trends on the star formation rate - stellar mass (SFR – M*) plane suggest that the most likely connection is a common gas reservoir for star formation and AGN, and that they both decline as the gas reservoir is consumed. The trends established at low-redshift could act as a local benchmark against which to compare higher redshift studies. As a complementary approach, we use a detailed case study of a nearby AGN host with integral field spectroscopy from the VLT/MUSE instrument in order to spatially resolve the interplay between AGN feedback and the host galaxy. We find that the galaxy substructure likely plays a role by collimating and/or obscuring the outflows and radiation from the central engine. Ongoing and future work with 3D spectroscopy will enable us to learn more about galaxy and black hole coevolution. Lastly, we briefly discuss lessons learnt from both approaches. [ABSTRACT FROM AUTHOR]

Starburst galaxies at z ∼ 2 – 4 are among the most intensely star-forming galaxies in the universe. The way they accrete their gas to form stars at such high rates is still a controversial issue. ALMA has detected the CH+ (J = 1-0) line in emission and/or absorption in all the gravitationally lensed starburst galaxies targeted so far at z ∼ 3. Its unique spectroscopic and chemical properties enable CH+ to highlight the sites of most intense dissipation of mechanical energy. The absorption lines reveal highly turbulent, massive reservoirs of low-density molecular gas. The broad emission lines, arising in myriad UV-irradiated molecular shocks, reveal powerful galactic winds. The CH+ lines therefore probe the fate of prodigious energy releases, due to infall and/or outflows, and primarily stored in turbulence before being radiated by cool molecular gas. The turbulent reservoirs act as mass and energy buffers over the duration of the starburst phase. [ABSTRACT FROM AUTHOR]

Galaxies and nuclei in dense environment at high redshift provide a good laboratory to investigate accelerated, most extreme evolution of galaxies. The SSA22 proto-cluster at z = 3.1 is known to have a three-dimensional 50 (comoving) Mpc-scale filamentary structure, traced by Lyα emitters, which makes the field a suitable target in this regard. To identify dust-obscured star-formation, a contiguous 20 arcmin2 region at the node of the cosmic structure was observed in ALMA band 6. In total 57 ALMA sources have been identified above 5σ, which makes the field one of the richest field in ALMA-identified (sub)millimeter galaxies. The follow-up spectroscopy confirmed about 20 sources as exact proto-cluster members so far. Together with high X-ray AGN fraction, our results suggest that the vigorous star formation activity and the growth of super massive black holes occurred simultaneously in the densest regions at z ∼ 3. [ABSTRACT FROM AUTHOR]

How galaxies reionized the universe remains an open question, but we can gain insights from the low-redshift Green Pea galaxies, one of the only known populations of Lyman continuum (LyC) emitters. Using VLA H i 21 cm observations and HST UV spectra of Green Peas, we investigate how neutral gas content and geometry influence LyC and Lyα escape. Our results suggest that LyC Emitters may have high ratios of star formation rate to H i mass. Low gas covering fractions are common among the population, but not all sightlines are optically thin. Based on the observed relationship between high ionization parameters, low metallicities, and narrow Lyα profiles, we propose that weak stellar feedback at low metallicities results in a gas geometry of dense clumps within a low-density medium, which facilitates Lyα and LyC escape. We address the implications of these results for identifying LyC emitters at high redshift with JWST and ALMA. [ABSTRACT FROM AUTHOR]

The completion of the Atacama Large Millimeter/submillimeter Array (ALMA) has led to the ability to make observations with unprecedented resolution at sub-millimeter wavelengths, allowing novel probes of the ISM and kinematics of high-redshift galaxies. Because they are magnified by foreground galaxies or clusters, gravitationally lensed galaxies allow the highest possible spatial resolution to be obtained, and/or a sharp reduction in the observing time required to detect faint objects or spectral lines. These benefits have made lensed galaxies useful benchmark systems for ALMA, enabling a wide variety of science cases. Here I focus in particular on spatially-resolved observations of massive galactic outflows in the very distant z > 4 universe, summarizing plausible tracers of the cold molecular phase of these outflows. The prospects of joint JWST and ALMA observations will be revolutionary, including the chance to take a full census of galactic outflows in multiple gas phases at matched spatial resolution. [ABSTRACT FROM AUTHOR]

I present an overview of the JWST Advanced Deep Extragalactic Survey (JADES), a joint program of the JWST/NIRCam and NIRSpec Guaranteed Time Observations (GTO) teams involving 950 hours of observation. We will target two well-studied fields with excellent supporting data (e.g., from HST-CANDELS): GOODS-North and South, including the Ultra Deep Field. The science goal of JADES is to chart galaxy evolution at z > 2, and potentially out to z > 10, using the rest-frame optical and near-IR though observations from ≍ 1–5μm. Multi-colour NIRCam imaging with 9 filters will enable photometric redshifts and the application of the Lyman break technique out to unprecedented distances. NIRSpec spectroscopy (with spectral resolving powers of R = 100, 1000 & 2700) will measure secure spectroscopic redshifts of the photometrically-selected population, as well as stellar continuum slopes in the UV rest-frame, and hence study the role of dust, stellar population age, and other effects. Measuring emission lines can constrain the dust extinction, star formation rates, metallicity, chemical abundances, ionization and excitation mechanism in high redshift galaxies. Coupling NIRCam and NIRSpec observations will determine stellar populations (age, star formation histories, abundances) of galaxies and provide the information to correct their broad-band spectral energy distribution for likely line contamination. Potentially we can search for signatures of Population III stars such as HeII. We can address the contribution of star-forming galaxies at z > 7 to reionization by determining the faint end slope of the luminosity function and investigating the escape fraction of ionizing photons by comparing the UV stellar continuum with the Balmer-line fluxes. [ABSTRACT FROM AUTHOR]

Understanding the ionizing spectrum of low-metallicity galaxies is of great importance for modeling and interpreting emission line observations of early/distant galaxies. Although a wide suite of stellar evolution, atmosphere, population synthesis, and photoionization models, taking many physical processes into account now exist, all models face a common problem: the inability to explain the presence of nebular Heii emission, which is observed in many low metallicity galaxies, both in UV and optical spectra. Several possible explanations have been proposed in the literature, including Wolf-Rayet (WR) stars, binaries, very massive stars, X-ray sources, or shocks. However, none has so far been able to explain the major observations. We briefly discuss the He ii problem, available empirical data, and observed trends combining X-ray, optical and other studies. We present a simple and consistent physical model showing that X-ray binaries could explain the long-standing nebular Heii problem. Our model, described in Schaerer et al. (2019), successfully explains the observed trends and strength of nebular He ii emission in large samples of low metallicity galaxies and in individual galaxies, which have been studied in detail and with multi-wavelength observations. Our results have in particular important implications for the interpretation of galaxy spectra in the early Universe, which will be obtained with upcoming and future facilities. [ABSTRACT FROM AUTHOR]

Current observations suggest an accelerated evolution of the cosmic star formation rate density for 8 < z < 10, indicating that galaxy assembly experienced an extremely intense phase during the first ∼600Myr years of cosmic time. We performed a systematic search of ultrabright star-forming galaxies at z ∼ 8 over the COSMOS/UltraVISTA survey, identifying 16 candidate Lyman-break galaxies. The still large uncertainties on the associated volume density do not yet allow us to ascertain whether a different star-formation efficiency (SFE) existed at early cosmic epochs. Leveraging the deepest Spitzer/IRAC data available from the GREATS program over the CANDELS/GOODS fields, we also constructed stacked SEDs of sub- L* LBGs at z ∼ 8. We find extreme nebular line emission (EW0 (Hα) ∼ 1000Å), high specific star-formation rates (∼10/Gyr) and indication of an inverse Balmer break. These results point toward very young ages (<100 Myr), and, combined with measurements at lower redshifts, that the SFE evolved only marginally during the first ∼1.5Gyr of cosmic history. [ABSTRACT FROM AUTHOR]

The advent of the Atacama Large Millimeter/submillimeter Array (ALMA) has enabled a new era for studies of the formation and assembly of distant galaxies. Cosmological deep field surveys with ALMA and other interferometers have flourished in the last few years covering wide ranges of galaxy properties and redshift, and allowing us to gain critical insights into the physical mechanisms behind the galaxy growth. Here, we present a brief review of recent studies that aim to characterize the interstellar medium properties of galaxies at high redshift (z > 1), focusing on blank-field ALMA surveys of dust continuum and molecular line emission. In particular, we show recent results from the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS) large program. [ABSTRACT FROM AUTHOR]

ISM comprises multiple components, including molecular, neutral, and ionized gas, and dust, which are related to each other mainly through star formation – some are fuel for star formation (molecular gas) while some are the products of it (ionized gas, dust). To fully understand the physics of star formation and its evolution throughout cosmic time, it is crucial to measure and observe different ISM components of galaxies out to high redshifts. I will review the current status of near-IR studies of galaxies during the peak of star formation activity (z ∼ 1 – 3). Using rest-frame optical emission lines, we measure dust, star formation, and gaseous properties of galaxies. JWST will advance such studies by probing lower luminosities and higher redshifts, owing to its significantly higher sensitivity. Incorporating ALMA observations of cold dust and molecular gas at z > 1 will give us a nearly complete picture of the ISM in high-redshift galaxies over a large dynamic range in mass. [ABSTRACT FROM AUTHOR]

Mapping the molecular gas content of the universe is key to our understanding of the build-up of galaxies over cosmic time. Spectral line scans in deep fields, such as the Hubble Ultra Deep Field (HUDF), provide a unique view on the cold gas content out to high redshift. By conducting 'spectroscopy-of-everything', these flux-limited observations are sensitive to the molecular gas in galaxies without preselection, revealing the cold gas content of galaxies that would not be selected in traditional studies. In order to capitalize on the molecular gas observations, knowledge about the physical conditions of the galaxies detected in molecular gas, such as their interstellar medium conditions, is key. Fortunately, deep surveys with integral-field spectrographs are providing an unprecedented view of the galaxy population, providing redshifts and measurements of restframe UV/optical lines for thousands of galaxies. We present the results from the synergy between the ALMA Spectroscopic Survey of the HUDF (ASPECS), with deep integral field spectroscopy from the MUSE HUDF survey and multi-wavelength data. We discuss the nature of the galaxies detected in molecular gas without preselection and their physical properties, such as star formation rate and metallicity. We show how the combination of ALMA and MUSE integral field spectroscopy can constrain the physical properties in galaxies located around the main sequence during the peak of galaxy formation. [ABSTRACT FROM AUTHOR]

Observations of star-forming galaxies in the distant Universe have confirmed the importance of massive stars in shaping galaxy emission and evolution. Distant stellar populations are unresolved, and the limited data available must be interpreted in the context of stellar population models. Understanding these populations, and their evolution with age and heavy element content is key to interpreting processes such as supernovae, cosmic reionization and the chemical enrichment of the Universe. With the upcoming launch of JWST and observations of galaxies within a billion years of the Big Bang, the uncertainties in modelling massive stars - particularly their interactions with binary companions - are becoming increasingly important to our interpretation of the high redshift Universe. In turn, observations of distant stellar populations provide ever stronger tests against which to gauge the success of, and flaws in, current massive star models. Here we briefly review the current status binary stellar population synthesis. [ABSTRACT FROM AUTHOR]

Spatially resolved studies of galaxies in the high-redshift Universe have traditionally been reliant on data at rest-frame optical and UV wavelengths, which can be biased towards the least dust-obscured galaxies. For several years now, we have been able to resolve and probe the morphology of longer-wavelength emission from distant galaxies with ALMA, and a number of recent ALMA studies were presented at the IAU Symposium No. 352. These included our study of the resolved multi-wavelength emission of galaxies at z ∼ 2. As part of the SHiZELS collaboration, we are mapping the Hα emission line (from SINFONI/VLT), UV continuum (from HST), and the far-infrared (from ALMA) emission from a small sample of Hα-selected galaxies. In this proceedings paper, we showcase the high quality of our data, and the spectacular structures displayed by one of our most dusty sources. We also provide an overview of some highly complementary simulation-based work, using galaxies drawn from the FIRE-2 zoom-in cosmological hydrodynamical simulations. Using sophisticated radiative transfer techniques, we have derived predictions for the spatially-resolved emission of a sample of star-forming galaxies, from rest-frame far-ultraviolet to the far-infrared. For both observed and simulated galaxies, emission maps show striking differences with wavelength, with the same galaxy appearing clumpy and extended in the far-ultraviolet yet compact at far-infrared wavelengths. [ABSTRACT FROM AUTHOR]

Submillimeter galaxies at z > 3 building up their central cores through compact starbursts with an effective radius of 1–2 kpc. Our ALMA high-resolution observations reveal off-center gas clumps in a submillimeter galaxy at z = 4.3, COSMOS-AzTEC-1, as well as a rotation-dominated disk. Exploiting the kinematic properties and the spatial distribution of gas mass surface density, we find that the starburst disk is gravitationally unstable. This result is consistent with a scenario where in-situ clumps are formed through disk instability. On the other hand, we find evidence for an ex-situ clump that does not corotate with the starburst disk. The accretion of such a non-corotating clump could stimulate violent disk instability, driving gas inflows into the central regions of the galaxy. Our results suggest that compact cores are formed through an extreme starburst due to a gravitational instability, triggered by non-corotating clumps. [ABSTRACT FROM AUTHOR]

Galaxies are complicated physical systems which obey complex scaling relationships; as a result, properties measured from broadband photometry are often highly correlated, degenerate, or both. Therefore, the accuracy of basic properties like stellar masses and star formation rates (SFRs) depend on the accuracy of many second-order galaxy properties, including star formation histories (SFHs), stellar metallicities, dust properties, and many others. Here, we re-assess measurements of galaxy stellar masses and SFRs using a 14-parameter physical model built in the Prospector Bayesian inference framework. We find that galaxies are ∼0.2 dex more massive and have ∼0.2 dex lower star formation rates than classic measurements. These measurements lower the observed cosmic star formation rate density and increase the observed buildup of stellar mass, finally bringing these two metrics into agreement at the factor-of-two level at 0.5 < z < 2.5. [ABSTRACT FROM AUTHOR]

The ALMA-ALPINE [CII] survey (A2C2S) aims at characterizing the properties of normal star-forming galaxies (SFGs) observed in the [CII]-158μm line in the period of rapid mass assembly at redshifts 4 < z < 6. Here we present the survey and the selection of 118 galaxies observed with ALMA, selected from large samples of galaxies with spectroscopic redshifts derived from UV-rest frame. The observed properties derived from the ALMA data are presented and discussed in terms of the overall detection rate in [CII] and far-IR continuum. The sample is representative of the SFG population at these redshifts. The overall detection rate is 61% down to a flux limit of 0.07 mJy. From a visual inspection of the [CII] data cubes together with the large wealth of ancillary data we find a surprisingly wide range of galaxy types, including 32.4% mergers, 25.7% extended and dispersion dominated, 13.5% rotating discs, and 16.2% compact, the remaining being too faint to be classified. ALPINE sets a reference sample for the gas distribution in normal star-forming galaxies at a key epoch in galaxy assembly, ideally suited for studies with future facilities like JWST and ELTs. [ABSTRACT FROM AUTHOR]

Characterising primeval galaxies entails the challenging goal of observing galaxies with modest star formation rates (SFR < 100 Mȯyr−1) and approaching the beginning of the reionisation epoch (z > 6). To date a large number of primeval galaxies have been identified thanks to deep near-infrared surveys. However, to further our understanding on the formation and evolution of such primeval objects, we must investigate their nature and physical properties through multi-band spectroscopic observations. Information on dust content, metallicity, interactions with the surrounding environment, and outflows can be obtained with ALMA observations of far-infrared (FIR) lines such as the [Cii] at 158 μm and [Oiii] at 88 μm. Here, we, thus, discuss the recent results unveiled by ALMA observations and present new [Cii] observations of BDF-3299, a star-forming galaxy at z = 7.1 showing a spatial and spectral offset between the rest-frame UV and the FIR lines emission. [ABSTRACT FROM AUTHOR]

Cosmological hydrodynamical simulations have become an important theoretical tool for understanding the formation and evolution of the first galaxies during cosmic dawn, between redshifts 5 and 15. I will introduce the FirstLight database of about 300 zoom-in simulations with a resolution of 10 parsecs. This database agrees well with observed UV luminosity functions and stellar mass functions. I will discuss the origin and evolution of the star-forming main sequence of galaxies and the main drivers of the star formation histories at these early epochs. I will show simulated SEDs from UV to IR, including stellar and nebular emission. The rest-frame UV spectra show steep slopes and a high production efficiency of Lyman continuum photons. These properties are consistent with young stellar populations with low metallicities. Simulated recombination lines allow us to link the physical conditions of the gas around these stellar populations with observables, like equivalent widths in OIII or Hα or BPT diagrams at high-z. These simulations are making predictions that will be tested for the first time in future deep fields with the James Webb Space Telescope (JWST). I will finally discuss preliminary results involving JWST mock fields and predictions for ALMA observations by post-processing FirstLight snapshots with Powderday radiative transfer code. [ABSTRACT FROM AUTHOR]

We present a suite of high-resolution cosmological zoom-in simulations of galaxies at z⩾ 5using the state-of-the-art models for the multi-phase ISM, star formation, and stellar feedback from the FIRE project. We present a series of key results from these simulations, including the stellar mass–halo mass relation, the ultraviolet luminosity functions, dust attenuation and dust temperatures, the ubiquitous formation of bound star clusters, morphology and clumpiness, and the escape fractions of ionizing photons from high-redshift galaxies. We discuss how different simulations in the literature agree and disagree and what observations are most useful for testing the models in the era of ALMA and JWST. [ABSTRACT FROM AUTHOR]

Luminous quasars are powered by accretion onto supermassive black holes. Such luminous quasars have been discovered up to the highest redshifts, z > 7. Here we discuss recent observations of the host galaxies of luminous quasars at z ≳ 6. We do not find a correlation between ongoing black hole growth and star-formation rate in the high redshift quasars, possibly indicating that black holes and their hosts do not co-evolve. We further show that even with high spatial resolution observations of the gas kinematics, dynamical mass estimates remain highly uncertain and should be used with caution. [ABSTRACT FROM AUTHOR]

Understanding properties of galaxies in the epoch of reionization (EoR) is a frontier in the modern astronomy. With the advent of ALMA, it has become possible to detect far-infrared fine structure lines (e.g. [CII] 158 μm and [OIII] 88 μm) and dust continuum emission in star-forming galaxies in the EoR. Among these lines, our team is focusing on [OIII] 88 μm observations in high-z galaxies. After the first detection of [OIII] in the epoch of reionization (EoR) in 2016 from our team at z = 7.21, there are now more than ten [OIII] detections at z > 6 up to z = 9.11. Interestingly, high-z galaxies typically have very high [OIII]-to-[CII] luminosity ratio ranging from 3 to 12 or higher, demonstrating [OIII] is a powerful tracer at high-z. The high luminosity ratios may imply that high-z galaxies have low gas-phase metallicity and/or high ionization states. [ABSTRACT FROM AUTHOR]

The JWST Advanced Deep Extragalactic Survey (JADES) is a joint program of the JWST NIRCam and NIRSpec Guaranteed Time Observation (GTO) teams involving over 800 hours of observation. This paper describes the imaging portion of the program which covers nearly 200 square arc minutes divided between two well-studied fields with excellent supporting data (e.g. from Chandra, ALMA, and HST-CANDELS): GOODS North and South, including the Ultra Deep Field. NIRCam imaging will enable the study of galaxy evolution to z ∼ 10 and higher using multi-color imaging with 9 filters covering 0.9 to 5 microns. Such data will provide photometric redshifts and a wealth of data for constructing luminosity and mass functions. A key component of the program is rapid turn around of imaging into NIRSpec target lists. Preparing for this program has benefited from the development of a mock catalog and simulated imaging to test these processes. [ABSTRACT FROM AUTHOR]

Thanks to the remarkable ALMA capabilities and the unique configuration of the Cosmic Snake galaxy behind a massive galaxy cluster, we could resolve molecular clouds down to 30 pc linear physical scales in a typical Milky Way progenitor at z = 1.036, through CO(4–3) observations performed at the ∼ 0.2″ angular resolution. We identified 17 individual giant molecular clouds. These high-redshift molecular clouds are clearly different from their local analogues, with 10–100 times higher masses, densities, and internal turbulence. They are offset from the Larson scaling relations. We argue that the molecular cloud physical properties are dependent on the ambient interstellar conditions particular to the host galaxy. We find these high-redshift clouds in virial equilibrium, and derive, for the first time, the CO-to-H2 conversion factor from the kinematics of independent molecular clouds at z = 1. The measured large clouds gas masses demonstrate the existence of parent gas clouds with masses high enough to allow the in-situ formation of similarly massive stellar clumps seen in the Cosmic Snake galaxy in comparable numbers. Our results support the formation of molecular clouds by fragmentation of turbulent galactic gas disks, which then become the stellar clumps observed in distant galaxies. [ABSTRACT FROM AUTHOR]

The spatial distribution of the dust and stars contains crucial information about the evolutionary pathways of galaxies. We present results of our study combing high-resolution ALMA and HST observations of z ∼ 2 bright sub-millimeter galaxies (SMGs). We have developed a two-dimensional extinction and age correction technique to obtain accurate stellar mass distributions from HST/CANDELS. For the first time, we can directly compare the spatial distribution of assembled stellar mass and ongoing star formation on kpc scales for distant SMGs, shedding light on their highly debated formation mechanisms. We find that the dust distribution is more compact than the stellar component, regardless if the SMG lies on the main sequence or at the starburst regime. Taking the dust emission as a proxy for dust-obscured star formation, our results imply that high-redshift SMGs are experiencing centrally enhanced star formation. These findings suggests that major galaxy interactions are not necessarily the main formation channel for SMGs with secular disk formation remaining a viable option as suggested by state-of-the-art cosmological simulations. The sizes and stellar densities of our z ∼ 2 SMGs agree well with the most compact early-type galaxies in the local Universe, strongly supporting the idea that the latter systems are indeed the descendants of massive SMGs at z ∼ 2. [ABSTRACT FROM AUTHOR]

We present new constraints on the cosmic cold molecular gas evolution out to redshift 6 based on systematic mining of the public ALMA archive in the COSMOS field (A3 COSMOS). Our A3 COSMOS dataset contains ∼ 700 galaxies (0.3 ≲ z ≲ 6) with high-confidence ALMA detection and multi-wavelength SEDs. Combining with ∼ 1,200 CO-observed galaxies at 0 ≲ z ≲ 4 (75% at z < 0.1) in the literature, we parameterize galaxies' molecular gas depletion time and gas fraction each as a function of stellar mass, offset from the star-forming main-sequence and cosmic age. We propose a new functional form which provides a better fit and implies a "downsizing" effect and "mass-quenching". By adopting galaxy stellar mass functions and applying our gas fraction function, we obtain a cosmic cold molecular gas density evolution in agreement with recent CO blind field surveys as well as semi-analytic modeling. These together provide us a coherent picture of galaxy cold molecular gas, SFR and stellar mass evolution. [ABSTRACT FROM AUTHOR]

The opportunities offered by JWST and the ELT for the detection and study of forming/just formed globular clusters at high redshifts are illustrated, also alluding at the unique insight we may get on the very early stages of galaxy formation. [ABSTRACT FROM AUTHOR]

While the high-redshift component of the CANDELS survey was designed with the z ∼ 6–8 era in mind, these data do probe the far-UV of galaxies at even higher redshift. A few studies have ventured this far out, and have published conflicting results - some continue to find significant star-formation, while others conclude there is a steep decline in this quantity. Here I report on a new search for z = 9–10 galaxies, making significant use of the Spitzer/IRAC data in the CANDELS fields. We have discovered a larger number of galaxies in this epoch than previous works, implying the UV luminosity function, and thus the SFR density, may not evolve as steeply as previously thought. This implies that star-formation begins early in the universe. I will also report on a new study searching for the earliest quenched galaxies at 3 < z < 5, which are not predicted by models, yet may exist if galaxies form very early, and thus can approach their quenching phase quicker. [ABSTRACT FROM AUTHOR]

Theoretical work suggests that AGNs play an important role in quenching star formation in massive galaxies. In addition to molecular outflows observed in the local universe, emission from very high-J CO rotational transitions have been a key piece of evidence for AGN directly affecting the molecular gas reservoirs that fuel star formation. However, very few observations exist of CO rotational lines past the peak of the CO spectral line energy distribution (SLED) for galaxies in the early universe. Here we present new ALMA observations of high-J CO rotational lines (from CO(5–4) to CO(16–15)) in six z > 2 IR-bright systems, including several sources not known to contain a strong AGN for comparison. We detect significant amounts of high-excitation CO emission that suggests the presence of energy sources beyond UV-heating. [ABSTRACT FROM AUTHOR]

We have entered an era where the gas mass estimates of distant galaxies do not rely on a single tracer but rather on an inventory of different and independent methods, much like the case for the determination of the star formation rate (SFR) of the galaxies. This is crucial as the traditional Mgas tracers, i.e. low-J CO transition lines and dust continuum emission are becoming highly uncertain as we move to higher redshifts due to metallicity and CMB effects. Here, we present a homogeneous and statistically significant investigation of the use of atomic carbon as an alternative Mgas tracer (Valentino et al.2018) and provide evidence of optically thick far-IR emission in high−z starbursts that point towards higher dust temperatures and lower dust and gas mass estimates than previously inferred (Cortzen et al.2019, submitted). Finally, we present direct observations of the effect of the CMB on the far-IR SEDs of high-z SBs, manifested by unphyscally large (β = 2.5–3.5) apparent spectral indexes in R-J tail (Jin et al. 2019, submitted). [ABSTRACT FROM AUTHOR]

Resolved observations of star-forming galaxies at cosmic noon with the Hubble Space Telescope and large ground-based facilities provide a view on the spatial distribution of stars, gas and dust, and probe gaseous motions revealing the central gravitational potential and local feedback processes at play. In this paper, we review recent insights gained from such observations, with an emphasis on results obtained through optical/near-infrared imaging and imaging spectroscopy. Their context and implications are documented more fully in a forthcoming review article by Förster Schreiber & Wuyts (in prep). [ABSTRACT FROM AUTHOR]

Using an ultra-deep, untargeted survey with the MUSE integral field spectrograph on the ESO Very Large Telescope, we obtain spectroscopic redshifts to a depth never explored before: galaxies with observed magnitudes m > 30–32. Specifically, we detect objects via Lyman-α emission at 2.9 < z < 6.7 without individual continuum counterparts in areas covered by the deepest optical/near-infrared imaging taken by the Hubble Space Telescope, the Hubble Ultra Deep Field. In total, we find more than 100 such objects in 9 square arcminutes at these redshifts, also including a number of sources that are visible only in the HST band that contains Lyman-α. Detailed HST and IRAC stacking analyses confirm the Lyman-α emission as well as the 1216 Å breaks, faint UV continua (MUV ∼ −15), and optical emission lines: these objects are the faintest spectroscopically-confirmed galaxies at high-z. The blue UV continuum slopes and measurements/limits on the equivalent widths of Lyman-α, which in some cases exceeds 300 Å, are consistent with ages < 10 Myr, metallicities < 5% solar, and stellar masses < 107–8 solar masses. The nature of these types of objects is intriguing as they could be the faint star-forming sources of Reionization and could represent the initial (strong) phase of stellar mass growth in galaxies. [ABSTRACT FROM AUTHOR]

The observed properties of the Lyman-α (Ly α) emission line are a powerful probe of neutral gas in and around galaxies. We present spatially resolved Ly α spectroscopy with VLT/MUSE targeting VR7, a UV-luminous galaxy at z  = 6.532 with moderate Ly α equivalent width (EW0 ≈ 38 Å). These data are combined with deep resolved [CII]158μm spectroscopy obtained with ALMA and UV imaging from HST and we also detect UV continuum with MUSE. Ly α emission is clearly detected with S/N ≈ 40 and FWHM of 374 km s−1. Ly α and [C  ii ] are similarly extended beyond the UV, with effective radius reff = 2.1 ± 0.2 kpc for a single exponential model or r |$_{\rm eff, Ly\alpha , halo} = 3.45^{+1.08}_{-0.87}$| kpc when measured jointly with the UV continuum. The Ly α profile is broader and redshifted with respect to the [C  ii ] line (by 213 km s−1), but there are spatial variations that are qualitatively similar in both lines and coincide with resolved UV components. This suggests that the emission originates from two components with plausibly different H  i column densities. We place VR7 in the context of other galaxies at similar and lower redshift. The Ly α halo scale length is similar at different redshifts and velocity shifts with respect to the systemic are typically smaller. Overall, we find little indications of a more neutral vicinity at higher redshift. This means that the local (∼10 kpc) neutral gas conditions that determine the observed Ly α properties in VR7 resemble the conditions in post-reionization galaxies. [ABSTRACT FROM AUTHOR]