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Recent observations reveal a rapid dust build-up in high-redshift galaxies (z > 4), challenging current models of galaxy formation. While our understanding of dust production and destruction in the interstellar medium (ISM) is advancing, probing baryonic processes in the early Universe remains a complex task. We characterize the evolution of 98 z~5 star-forming galaxies observed as part of the ALPINE survey by constraining the physical processes underpinning the gas and dust production, consumption, and destruction in their ISM. We make use of chemical evolution models to simultaneously reproduce the observed dust and gas content. For each galaxy, we estimate initial gas mass, inflows and outflows, and efficiencies of dust growth and destruction. We test the models with the canonical Chabrier and top-heavy initial mass functions (IMFs), with the latter enabling rapid dust production on shorter timescales. Our models successfully reproduce gas and dust content in older galaxies (> 600 Myr) regardless of the IMF, with Type II SNe as the primary dust source and no dust growth in ISM with moderate inflow of primordial gas. In case of intermediate-age galaxies (300 - 600 Myr), we reproduce the gas and dust content through Type II SNe and dust growth in ISM, though we observe an over-prediction of dust mass in older galaxies, potentially indicating an unaccounted dust destruction mechanism and/or an overestimation of the observed dust masses. The number of young galaxies (< 300 Myr) reproduced, increases for models assuming top-heavy IMF but with maximal prescriptions of dust production. Galactic outflows are necessary to reproduce observed gas and dust masses. The Chabrier IMF models reproduce 65% of galaxies, while top-heavy IMF models improve this to 93%, easing tensions with observations. Upcoming JWST data will refine these models by resolving degeneracies in intrinsic galaxy properties., Comment: Accepted for publication in A&A

Galaxy protoclusters are sites of rapid growth, with a high density of massive galaxies driving elevated rates of star formation and accretion onto supermassive black holes. Here, we present new JWST/NIRSpec IFU observations of the J1000+0234 group at $z=4.54$, a dense region of a protocluster hosting a massive, dusty star forming galaxy (DSFG). The new data reveal two extended, high-equivalent-width (EW$_0>1000\r{A}$) [O III] nebulae that appear at both sides of the DSFG along its minor axis (namely O3-N and O3-S). On one hand, the spectrum of O3-N shows a broad and blueshifted component with a full width at half maximum (FWHM) of 1300 km/s, suggesting an outflow origin. On the other hand, O3-S stretches over 8.6 kpc, and has a velocity gradient that spans 800 km/s, but shows no evidence of a broad component. However, both sources seem to be powered by an active galactic nucleus (AGN), so we classified them as extended emission-line regions (EELRs). The strongest evidence comes from the detection of the high-ionization [Ne V] $\lambda 3427$ line toward O3-N, which paired with the lack of hard X-rays implies an obscuring column density above the Compton-thick regime. The [Ne V] line is not detected in O3-S, but we measure a He II $\lambda 4687$/H$\beta$=0.25, which is well above the expectation for star formation. Despite the remarkable alignment of O3-N and O3-S with two radio sources, we do not find evidence of shocks from a radio jet that could be powering the EELRs. We interpret this as O3-S being externally irradiated by the AGN, akin to the famous Hanny's Voorwerp object in the local Universe. In addition, classical line ratio diagnostics (e.g., [O III]/H$\beta$ vs [N II]/H$\alpha$) put the DSFG itself in the AGN region of the diagrams, and therefore suggest it to be the most probable AGN host. These results showcase the ability of JWST to unveil obscured AGN at high redshifts., Comment: 13 pages, 10 figures, and one table. Accepted for publication in A&A on November 12th 2024

The current standard model of cosmology successfully describes a variety of measurements, but the nature of its main ingredients, dark matter and dark energy, remains unknown. Euclid is a medium-class mission in the Cosmic Vision 2015-2025 programme of the European Space Agency (ESA) that will provide high-resolution optical imaging, as well as near-infrared imaging and spectroscopy, over about 14,000 deg^2 of extragalactic sky. In addition to accurate weak lensing and clustering measurements that probe structure formation over half of the age of the Universe, its primary probes for cosmology, these exquisite data will enable a wide range of science. This paper provides a high-level overview of the mission, summarising the survey characteristics, the various data-processing steps, and data products. We also highlight the main science objectives and expected performance., Comment: Accepted for publication in the A&A special issue`Euclid on Sky'

Near- to mid-Infrared observations (from Spitzer and JWST) have revealed a hidden population of galaxies at redshift z=3-6, called optically-dark objects, which are believed to be massive and dusty star-formers. While optically-dark sources are widely recognized as a significant component of the stellar mass function, the history of their stellar mass assembly remains unexplored. However, they are thought to be the progenitors of the more massive early-type galaxies found in present-day groups and clusters. It is thus important to examine the possible connection between dark sources and merging events, in order to understand the environment in which they live. Here, we report our search for close companions in a sample of 19 optically-dark objects identified in the SMACS0723 JWST deep field. They were selected in the NIRCam F444W band and undetected below 2mu. We restrict our analysis to the reddest (i.e. F277W-F444W> 1.3) and brightest (F444W< 26 mag) objects. We have identified an optically-dark source showing a very close companion (<0.5"). The spatially resolved SED fitting procedure indicates that all components lying within 1.5" from the dark source are indeed at z~5.7. Tidal features (leading to a whale shaped morphology) corroborate the hypothesis that the dark source is the most massive (log(M/Msun)>10.3) and dusty (Av~3 at the core) system of an ongoing merger with a mass ratio of ~10. Similar merging systems are identified in the SERRA simulations, allowing us to reconstruct their stellar mass assembly history and predict their molecular gas properties The discovery of mergers within dark galaxies at the end of the Epoch of Reionization underscores the importance of conducting a statistical search for additional candidates in deep NIRCam fields. Such research will aid in understanding the role of merging processes during the obscured phase of stellar mass accumulation., Comment: Accepted for publication in Astronomy & Astrophysics

Stellar bars are common morphological structures in the local Universe; according to optical and NIR surveys, they are present in about two-thirds of disc galaxies. These elongated structures are also believed to play a crucial role in secular evolutionary processes, because they are able to efficiently redistribute gas, stars, and angular momentum within their hosts, although it remains unclear as to whether they enhance or suppress star formation. A useful tool to investigate this ambiguity is the main sequence (MS) relation, which tightly links stellar mass ($M_{\star}$) and star formation rate (SFR). The main goal of this work is to explore star-formation processes in barred galaxies in order to assess the relevance of bars in star-formation quenching and whether or not they affect the typical log-linear trend of the resolved MS. To this purpose, we carried out a spatially resolved analysis on subkiloparsec (subkpc) scales for a sample of six nearby barred galaxies. We collected multi-wavelength photometric data from far-ultraviolet (FUV) to far-infrared (FIR) from the DustPedia database and applied a panchromatic spectral energy distribution (SED) fitting procedure on square apertures of fixed angular size (8" $\times$ 8") using the magphys code. For each galaxy, we obtain the distributions of stellar mass and SFR surface density and relate them in the $\log \Sigma_{\star}$ - $\log \Sigma_{\rm SFR}$ plane, deriving the spatially resolved MS relation. Although significant galaxy-to-galaxy variations are in place, we infer the presence of a common anti-correlation track in correspondence with the bar-hosting region, which shows systematically lower SFRs. This central quiescent signature can be interpreted as the result of a bar-driven depletion of gas reservoirs and a consequent halting of star formation. Our findings appear to support an inside-out quenching scenario., Comment: 15 pages, 6 figures, corrected typos, published in A&A

The main sequence (MS) of star-forming galaxies (SFGs) is the tight relation between the galaxy stellar mass and its star formation rate (SFR) and was observed up to z ~ 6. The MS relation can be used as a reference for understanding the differences among galaxies, characterised by different rates of stellar production (starbursts, SFGs, and passive galaxies), and those inside a galaxy made up of different components (bulge, disk, and halo). To investigate peculiar features found in our sample galaxies, we focus here on their star formation history (SFH). We performed a spectral energy distribution fitting procedure that accounted for the energetic balance between UV and far-IR radiation on a sample of eight nearby face-on spiral galaxies from the DustPedia sample. This approach allowed us to study the spatially resolved MS of the sample and to recover the past SFH. By exploiting the BAGPIPES code, we constrained the SFHs for each galaxy with a delayed exponentially declining model to derive their mass-weighted age (tMW). A central old region (tMW up to~7Gyr, consistent with the presence of a bulge for various systems) is followed by younger regions in which the disks are still forming stars (tMW~4Gyr). At larger distances, tMW increases mildly in general. Strikingly, in two galaxies (NGC4321 and NGC5194), we found a steep increase in tMW that reached levels similar to those of the bulge. These old stellar populations in the very galaxy outskirts are unexpected. We discuss their potential origin by considering the different gas phases of the source with the most prominent quenched ring, NGC4321, and argue for two main possibilities: 1) some environmental effect (e.g. starvation) or 2) the circumgalactic medium of sources outside of high-density clusters might have stopped to supply pristine gas to the galaxy (e.g. if its specific angular moment is too high for being accreted)., Comment: Accepted for publication on Astronomy and Astrophysics

Simulations predict that the galaxy populations inhabiting protoclusters may contribute considerably to the total amount of stellar mass growth of galaxies in the early universe. In this study, we test these predictions observationally, focusing on the Taralay protocluster (formerly PCl J1001+0220) at $z \sim 4.57$ in the COSMOS field. Leveraging data from the Charting Cluster Construction with VUDS and ORELSE (C3VO) survey, we spectroscopically confirmed 44 galaxies within the adopted redshift range of the protocluster ($4.48 < z < 4.64$) and incorporate an additional 18 such galaxies from ancillary spectroscopic surveys. Using a density mapping technique, we estimate the total mass of Taralay to be $\sim 1.7 \times 10^{15}$ M$_\odot$, sufficient to form a massive cluster by the present day. By comparing the star formation rate density (SFRD) within the protocluster (SFRD$_\text{pc}$) to that of the coeval field (SFRD$_\text{field}$), we find that SFRD$_\text{pc}$ surpasses the SFRD$_\text{field}$ by $\Delta$log(SFRD/$M_\odot$ yr$^{-1}$ Mpc$^{-3}$) = $1.08 \pm 0.32$ (or $\sim$ 12$\times$). The observed contribution fraction of protoclusters to the cosmic SFRD adopting Taralay as a proxy for typical protoclusters is $33.5\%^{+8.0\%}_{-4.3\%}$, a value $\sim$2$\sigma$ in excess of the predictions from simulations. Taralay contains three peaks that are $5\sigma$ above the average density at these redshifts. Their SFRD is $\sim$0.5 dex higher than the value derived for the overall protocluster. We show that 68% of all star formation in the protocluster takes place within these peaks, and that the innermost regions of the peaks encase $\sim 50\%$ of the total star formation in the protocluster. This study strongly suggests that protoclusters drive stellar mass growth in the early universe and that this growth may proceed in an inside-out manner., Comment: 26 pages, 14 figures, 10 tables

We present six spectroscopically confirmed massive protostructures, spanning a redshift range of $2.59000$\thinspace cMpc$^3$) of more than $2.5\sigma_{\delta}$ above the field density levels at these redshifts, have a total mass $M_{tot}\ge10^{14.8}M_\odot$ and one or more highly overdense (overdensity$\thinspace>5\sigma_{\delta}$) peaks. One of the most complex protostructures discovered is a massive ($M_{tot}=10^{15.1}M_\odot$) system at $z\sim3.47$ that contains six peaks and 55 spectroscopic members. We also discover protostructures at $z\sim3.30$ and $z\sim3.70$ that appear to at least partially overlap on sky with the protostructure at $z\sim3.47$, suggesting a possible connection. We additionally report on the discovery of three massive protostructures at $z=2.67$, 2.80, and 4.14 and discuss their properties. Finally, we discuss the relationship between star formation rate and environment in the richest of these protostructures, finding an enhancement of star formation activity in the densest regions. The diversity of the protostructures reported here provide an opportunity to study the complex effects of dense environments on galaxy evolution over a large redshift range in the early universe., Comment: 10 pages, 4 figures, 1 table

Context: From redshift 6 to redshift $\approx$ 4 galaxies grow rapidly from low mass galaxies towards the more mature massive galaxies we see at the cosmic noon. Growth via gas accretion and mergers undoubtedly shape this evolution - however, there currently exists much uncertainty over the contribution of each of these processes to the overall evolution of galaxies. Furthermore, previous characterisations of the morphology of galaxies in the molecular gas phase has been limited by the coarse resolution of previous observations. Aims: The goal of this paper is to derive the morpho-kinematic properties of 3 main-sequence systems at $z\sim4.5$, drawn from the ALPINE survey, using brand new high-resolution ALMA data in band 7. The objects were previously characterised as one merger with three components, and and two dispersion-dominated galaxies. Methods: We use intensity and velocity maps, position-velocity diagrams and radial profiles of [CII], in combination with dust continuum maps, to analyse the morphology and kinematics of the 3 systems.} Results: In general, we find that the high-resolution ALMA data reveal more complex morpho-kinematic properties. We identify in one galaxy interaction-induced clumps, showing the profound effect that mergers have on the molecular gas in galaxies, consistent with what is suggested in recent simulations. A galaxy that was previously classified as dispersion dominated turned out to show two bright [CII] emission regions, that could either be merging galaxies or massive star-forming regions within the galaxy itself. The high resolution data for the other dispersion dominated object also revealed clumps of [CII] that were not previously identified. Within the sample, we might also detect star-formation powered outflows (or outflows from Active Galactic Nuclei) which appear to be fuelling diffuse gas regions and enriching the circumgalactic medium., Comment: Submitted to A&A, 13 pages

The Kennicutt-Schmidt (KS) relation between the gas and the star formation rate (SFR) surface density ($\Sigma_{\rm gas}$-$\Sigma_{\rm SFR}$) is essential to understand star formation processes in galaxies. So far, it has been measured up to z~2.5 in main-sequence galaxies. In this letter, we aim to put constraints at z~4.5 using a sample of four massive main-sequence galaxies observed by ALMA at high resolution. We obtained ~0.3"-resolution [CII] and continuum maps of our objects, which we then converted into gas and obscured SFR surface density maps. In addition, we produced unobscured SFR surface density maps by convolving Hubble ancillary data in the rest-frame UV. We then derived the average $\Sigma_{\rm SFR}$ in various $\Sigma_{\rm gas}$ bins, and estimated the uncertainties using a Monte Carlo sampling. Our galaxy sample follows the KS relation measured in main-sequence galaxies at lower redshift and is slightly lower than predictions from simulations. Our data points probe the high end both in terms of $\Sigma_{\rm gas}$ and $\Sigma_{\rm gas}$, and gas depletion timescales (285-843 Myr) remain similar to z~2 objects. However, three of our objects are clearly morphologically disturbed, and we could have expected shorter gas depletion timescales (~100 Myr) similar to merger-driven starbursts at lower redshifts. This suggests that the mechanisms triggering starbursts at high redshift may be different than in the low- and intermediate-z Universe., Comment: 9 pages, 7 figures, 2 tables, accepted by A&A (letter)

Motivated by spectroscopic confirmation of three overdense regions in the COSMOS field at $z\sim3.35$, we analyze the uniquely deep multi-wavelength photometry and extensive spectroscopy available in the field to identify any further related structure. We construct a three dimensional density map using the Voronoi tesselation Monte Carlo method and find additional regions of significant overdensity. Here we present and examine a set of six overdense structures at $3.205\sigma$ overdensity separated by up to 70 cMpc, suggestive of a proto-supercluster similar to the Hyperion system at $z\sim2.45$. Upcoming photometric surveys with JWST such as COSMOS-Web, and further spectroscopic follow-up will enable more extensive analysis of the evolutionary effects that such an environment may have on its component galaxies at these early times., Comment: Accepted for publication in MNRAS. 7 pages, 3 figures, 3 tables

The physical processes which make a galaxy a Lyman Alpha Emitter have been extensively studied for the past 25 years. However, the correlations between physical and morphological properties of galaxies and the strength of the Ly$\alpha$ emission line are still highly debated. Therefore, we investigate the correlations between the rest-frame Ly$\alpha$ equivalent width and stellar mass, star formation rate, dust reddening, metallicity, age, half-light semi-major axis, S\'ersic index and projected axis ratio in a sample of 1578 galaxies in the redshift range $2 \leq z \leq 7.9$ from the GOODS-S, UDS and COSMOS fields. From the large sample of Ly$\alpha$ emitters (LAEs) in the dataset we find that LAEs are typically common main sequence star forming galaxies which show stellar mass $ \leq 10^9 \text{M}_{\odot}$, star formation rate $ \leq 10^{0.5} \text{M}_{\odot}/\text{yr}$, $E(B-V) \leq 0.2$ and half-light semi-major axis $\leq 1 \text{kpc}$. Building on these findings we develop a new method based on Random Forest (i.e. a Machine Learning classifier) in order to select galaxies which have the highest probability of being Ly$\alpha$ emitters. When applied to a population in the redshift range $z \in [2.5, 4.5]$, our classifier holds a $(80 \pm 2)\%$ accuracy and $(73 \pm 4)\%$ precision. At higher redshifts ($z \in [4.5, 6]$), we obtain a $73\%$ accuracy and a $80\%$ precision. These results highlight it is possible to overcome the current limitations in assembling large samples of LAEs by making informed predictions that can be used for planning future large scale spectroscopic surveys., Comment: Accepted for publication in the 4. Extragalactic astronomy section of Astronomy & Astrophysics, 13 pages, 13 figures

We report on the first experiment dedicated to the study of nuclear reactions on dopants in a cryogenic capsule at the National Ignition Facility (NIF). This was accomplished using bromine doping in the inner layers of the CH ablator of a capsule identical to that used in the NIF shot N140520. The capsule was doped with 3$\times$10$^{16}$ bromine atoms. The doped capsule shot, N170730, resulted in a DT yield that was 2.6 times lower than the undoped equivalent. The Radiochemical Analysis of Gaseous Samples (RAGS) system was used to collect and detect $^{79}$Kr atoms resulting from energetic deuteron and proton ion reactions on $^{79}$Br. RAGS was also used to detect $^{13}$N produced dominantly by knock-on deuteron reactions on the $^{12}$C in the ablator. High-energy reaction-in-flight neutrons were detected via the $^{209}$Bi(n,4n)$^{206}$Bi reaction, using bismuth activation foils located 50 cm outside of the target capsule. The robustness of the RAGS signals suggest that the use of nuclear reactions on dopants as diagnostics is quite feasible.

Optical rest-frame spectroscopic diagnostics are usually employed to distinguish between star formation and AGN-powered emission. However, this method is biased against dusty sources, hampering a complete census of the AGN population across cosmic epochs. To mitigate this effect, it is crucial to observe at longer wavelengths in the rest-frame near-infrared (near-IR), which is less affected by dust attenuation and can thus provide a better description of the intrinsic properties of galaxies. AGN diagnostics in this regime have not been fully exploited so far, due to the scarcity of near-IR observations of both AGNs and star-forming galaxies, especially at redshifts higher than 0.5. Using Cloudy photoionization models, we identify new AGN - star formation diagnostics based on the ratio of bright near-infrared emission lines, namely [SIII] 9530 Angstrom, [CI] 9850 Angstrom, [PII] 1.188 $\mu m$, [FeII] $1.257 \mu m$, and [FeII] $1.64 \mu m$ to Paschen lines (either Pa$\gamma$ or Pa$\beta$), providing simple, analytical classification criteria. We apply these diagnostics to a sample of 64 star-forming galaxies and AGNs at 0 < z < 1, and 65 sources at 1 < z < 3 recently observed with JWST-NIRSpec in CEERS. We find that the classification inferred from the near-infrared is broadly consistent with the optical one based on the BPT and the [SII]/H$\alpha$ ratio. However, in the near-infrared, we find $\sim 60 \%$ more AGNs than in the optical (13 instead of 8), with 5 sources classified as 'hidden' AGNs, showing a larger AGN contribution at longer wavelengths, possibly due to the presence of optically thick dust. The diagnostics we present provide a promising tool to find and characterize AGNs from z=0 to z=3 with low and medium-resolution near-IR spectrographs in future surveys., Comment: Paper accepted for publication in A&A on 05/09/2023. Three public Github repositories include: (1) a table with emission line measurements for the paper sample : https://github.com/Anthony96/Line_measurements_nearIR , Cloudy emission line predictions for star-forming galaxies and AGN models : https://github.com/Anthony96/star-forming_models , https://github.com/Anthony96/AGN_models

The Common Core State Standards in Mathematics (CCSS-M) were released in 2010 with a goal to improve critical thinking skills and prepare all students to thrive in college, careers, and as informed citizens. The Next Generation Science Standards (NGSS) followed in 2013. Using districtwide surveys of students in grades 6-8, conducted annually from 2011 through 2018; annual data on student achievement; surveys of teachers in the 2014-15 and 2017-18 school years; and interviews of teacher-leaders, school principals, and district officials, this study examines the results of district efforts to implement the CCSS-M and NGSS standards in Chicago. Findings include: (1) Math and science instruction improved in Chicago during the years of standards reform. In math, the largest improvements in instructional experiences and test gains occurred among students with the lowest tested skills; (2) Professional learning--defined broadly to include teacher collaboration, coaching, and workshops--was the most support that was most strongly associated with instructional change; (3) Collaboration around instructional improvement required dedicated time, multiple people with expertise, buy-in, trust, and administrator support; (4) Instructional resources provided by the district were helpful for implementing strong practices when they were instruction-ready, while other resources showed a null or negative relationship with practices; and (5) Instructional practices were significantly related to student achievement gains in both math and science. [This report was written with Jeanne Century, Debbie Leslie, Lisa Sall, and Nick Tallant.]

GDS J033218.92-275302.7 (here GS-14) is a $z\sim5.5$ galaxy detected in [CII] as part of the ALPINE survey with unusual UV spectral features that have been interpreted as signatures of either a double stellar population or of an active galactic nucleus (AGN). We exploited the multi-wavelength coverage of GS-14 to investigate the properties and the origin of its emission. We performed UV-to-NIR SED-fitting, with single/double stellar population and/or AGN component. We analyzed the VIMOS spectrum, which shows highly-ionized emission lines (Ovi, Nv, and Niv). The line properties have been compared with those observed in galaxies and AGN, and with the predictions from radiation transfer models for star-forming galaxies, AGN, and shocks. The SED-fitting provides a total stellar mass of $M_*=(4 \pm 1) \times 10^{10} M_\odot$, an age of the main stellar population of $\sim670 Myr$ and a recent short (8 Myr) burst of star formation (SF) of $\sim 90 M_\odot yr^{-1}$. The Nv line has a characteristic P-Cygni profile, which suggests a $\sim 3 Myr$ old population of stars with a mass of $\sim 5 \times10^{7} M_\odot$. The Nv profile also shows evidence for an additional component of nebular emission. The comparison of the line ratios with theoretical models allows us to associate the emission with SF or AGN, but the strong radiation field required to ionize the Ovi is more commonly related to AGN activity. We found evidence for an old and already evolved stellar population at $z\sim 5.5$ and show that the galaxy is experiencing a second short burst of SF. In addition, GS-14 carries signatures of obscured AGN activity. The AGN could be responsible for the short depletion time of this galaxy, thus making GS-14 one of the two ALPINE sources with hints of an active nucleus and an interesting target for future follow-ups., Comment: Accepted in A&A, 10 pages, 4 figures

A wealth of extragalactic populations completely missed at UV-optical wavelengths has been identified in the last decade, combining the deepest HST and Spitzer observations. These dark sources are thought to be very dusty and star-forming systems at 3

The circumgalactic medium (CGM) is the location where the interplay between large-scale outflows and accretion onto galaxies occurs. Metals in different ionization states flowing between the circumgalactic and intergalactic mediums are affected by large galactic outflows and low-ionization state inflowing gas. Observational studies on their spatial distribution and their relation with galaxy properties may provide important constraints on models of galaxy formation and evolution. To provide new insights into the spatial distribution of the circumgalactic of star-forming galaxies, we select a sample of 238 close pairs at $1.5 < z <4.5$ ($\langle z\rangle\sim$2.6) from the VIMOS Ultra Deep Survey. We then generate composite spectra by co-adding spectra of $background$ galaxies that provide different sight-lines across the CGM to examine the spatial distribution of the gas located around these galaxies and investigate possible correlations between the strength of the low- and high-ionization absorption features with different galaxy properties. We detect C II, Si II, Si IV and C IV) up to separations $\langle b \rangle=$ 172 kpc and 146 kpc. Our $W_{0}$ radial profiles suggest a potential redshift evolution for the CGM gas content producing these absorptions. We find a correlation between C II and C IV with star formation rate, stellar mass and trends with galaxy size estimated by the effective radius and azimuthal angle. Galaxies with high star formation rate show stronger C IV absorptions compared with star-forming galaxies with low SFR and low stellar mass. These results could be explained by stronger outflows, softer radiation fields unable to ionize high-ionization state lines or by the galactic fountain scenario where metal-rich gas ejected from previous star-formation episodes fall back to the galaxy., Comment: Accepted for publication in A&A

A multiwavelength study of galaxies is important to understand their formation and evolution. Only in the recent past, thanks to the Atacama Large (Sub) Millimeter Array (ALMA), were we able to study the far-infrared (IR) properties of galaxies at high redshifts. In this article, we summarize recent research highlights and their significance to our understanding of early galaxy evolution from the ALPINE survey, a large program with ALMA to observe the dust continuum and 158um C+ emission of normal star-forming galaxies at z = 4-6. Combined with ancillary data at UV through near-IR wavelengths, ALPINE provides the currently largest multiwavelength sample of post-reionization galaxies and has advanced our understanding of (i) the demographics of C+ emission; (ii) the relation of star formation and C+ emission; (iii) the gas content; (iv) outflows and enrichment of the intergalactic medium; and (v) the kinematics, emergence of disks, and merger rates in galaxies at z > 4. ALPINE builds the basis for more detailed measurements with the next generation of telescopes, and places itself as an important post-reionization baseline sample to allow a continuous study of galaxies over 13 billion years of cosmic time., Comment: 29 pages, 6 figures; Invited article for the special issue "Recent Advances in Infrared Galaxies and AGN", edited by Anna Sajina and Asantha R. Cooray, in Universe

We present the average [CII] $158\,\rm{\mu m}$ emission line sizes of UV-bright star-forming galaxies at $z\sim7$. Our results are derived from a stacking analysis of [CII] $158\,\rm{\mu m}$ emission lines and dust continua observed by ALMA, taking advantage of the large program Reionization Era Bright Emission Line Survey (REBELS). We find that the average [CII] emission at $z\sim7$ has an effective radius $r_e$ of $2.2\pm0.2\,\rm{kpc}$. It is $\gtrsim2\times$ larger than the dust continuum and the rest-frame UV emission, in agreement with recently reported measurements for $z\lesssim6$ galaxies. Additionally, we compared the average [CII] size with $4

The luminosity functions at z < 4 - 5 suggest that most galaxies have a relatively low stellar mass (logM_star = 10) and a low dust attenuation (A_FUV = 1.0). The physical properties of these objects are quite homogeneous. We used an approach where we combined their rest-frame far-infrared and submillimeter emissions and utilized the universe and the redshift as a spectrograph to increase the amount of information in a collective way. From a subsample of 27 ALMA-detected galaxies at z > 4.5, we built an infrared spectral energy distribution composite template. It was used to fit, with CIGALE, the 105 galaxies (detections and upper limits) in the sample from the FUV to the FIR. The derived physical parameters provide information to decipher the nature of the dust cycle and of the stellar populations in these galaxies. The derived IR composite template is consistent with the galaxies in the studied sample. A delayed star formation history with tau_main = 500 Myrs is slightly favored by the statistical analysis as compared to a delayed with a final burst or a continuous star formation history. The position of the sample in the star formation rate (SFR)- M_star diagram is consistent with previous papers. The redshift evolution of the log M_star versus A_FUV relation is in agreement with evolution in the redshift of this relation. This evolution is necessary to explain the cosmic evolution of the average dust attenuation of galaxies. Evolution is also observed in the L_dust/ L_FUV (IRX) versus UV slope beta_FUV diagram: younger galaxies have bluer beta_FUV. We modeled the shift of galaxies in the IRX versus the beta_FUV diagram with the mass-weighted age as a free parameter, and we provide an equation to make predictions., Comment: 40 pages, 13 figures

The [CII] 158$~\mu$m emission line represents so far one of the most profitable tools for the investigation of the high-redshift galaxies in the early Universe. Being one of the brightest cooling lines in the rest-frame far-infrared regime of star-forming galaxies, it has been successfully exploited as a tracer of star-formation rate (SFR) in local sources. The picture is more complex at higher redshifts, where its usability in this context is still under investigation. Recent results from the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) survey suggest that there is no (or weak) evolution of the L$\mathrm{_{[CII]}}$-SFR relation up to $z\sim6$ but their reliability is hampered by the presence of a large population of [CII] non-detected galaxies. In this work, we characterize the population of [CII] non-detections in ALPINE. By stacking their ALMA spectra, we obtain a signal detected at $\sim5.1\sigma$, resulting in a [CII] luminosity of $\mathrm{log(L_\mathrm{[CII]}}/\mathrm{L_{\odot}})$ $\sim7.8$. When combining this value with those from the [CII] detections, we find a $\mathrm{L_{[CII]}}$-SFR relation with a slope $b=1.14\pm0.11$, in agreement within the uncertainties both with the linear relation found in the local Universe, and with the previous findings from ALPINE at $z\sim5$. This suggests that the [CII] line can be considered a good tracer of star formation up to the distant Universe. Finally, we show that the galaxies of our sample that most deviate from the observed L$_\mathrm{[CII]}$-SFR relation could suffer from a less precise redshift estimation, perhaps artificially reducing their [CII] luminosity. In this respect, we claim that there is no evidence in favour of a deficit of [CII] content in high-z galaxies, in contrast with earlier studies., Comment: Accepted for publication in A&A. 10 pages, 5 figures

We present $10$ main-sequence ALPINE galaxies (log($M/M_{\odot}$) = 9.2-11.1 and ${\rm SFR}=23-190\,{\rm M_{\odot}\,yr^{-1}}$) at $z\sim4.5$ with optical [OII] measurements from Keck/MOSFIRE spectroscopy and Subaru/MOIRCS narrow-band imaging. This is the largest such multi-wavelength sample at these redshifts, combining various measurements in the ultra-violet, optical, and far-infrared including [CII]$_{158{\rm \mu m}}$ line emission and dust continuum from ALMA and H$\alpha$ emission from Spitzer photometry. For the first time, this unique sample allows us to analyze the relation between [OII] and total star-formation rate (SFR) and the interstellar medium (ISM) properties via [OII]/[CII] and [OII]/\halpha luminosity ratios at $z\sim4.5$. The [OII]$-$SFR relation at $z\sim4.5$ cannot be described using standard local descriptions, but is consistent with a metal-dependent relation assuming metallicities around $50\%$ solar. To explain the measured dust-corrected luminosity ratios of $L[OII]/L[CII] \sim 0.98^{+0.21}_{-0.22}$ and $L[OII]/LHa \sim -0.22^{+0.13}_{-0.15}$ for our sample, ionization parameters $\log(U)< -2$ and electron densities $\log(\rm n_e / {\rm [cm^{-3}]}) \sim 2.5-3$ are required. The former is consistent with galaxies at $z\sim2-3$, however lower than at $z>6$. The latter may be slightly higher than expected given the galaxies' specific SFR. The analysis of this pilot sample suggests that typical log($ M/M_{\odot})$ > 9 galaxies at $z\sim4.5$ to have broadly similar ISM properties as their descendants at $z\sim2$ and suggest a strong evolution of ISM properties since the Epoch of Reionization at $z>6$., Comment: 14 pages, 8 figures, Accepted for publication to MNRAS

We use a sample of 706 galaxies, selected as [OII]$\lambda$3727 ([OII]) emitters in the Survey for High-$z$ Absorption Red and Dead Sources (SHARDS) on the CANDELS/GOODS-N field, to study the differential attenuation of the nebular emission with respect to the stellar continuum. The sample includes only galaxies with a counterpart in the infrared and $\mathrm{log}_{10}(M_{*}/\mathrm{M}_{\odot})$ $>$ 9, over the redshift interval 0.3 $\lesssim$ $z$ $\lesssim$ 1.5. Our methodology consists in the comparison of the star formation rates inferred from [OII] and H$\alpha$ emission lines with a robust quantification of the total star-forming activity (${SFR}_{\mathrm{TOT}}$) that is independently estimated based on both infrared and ultraviolet (UV) luminosities. We obtain $f$$=$$E(B-V)_{\mathrm{stellar}}$/$E(B-V)_{\mathrm{nebular}}$ $=$ 0.69$^{0.71}_{0.69}$ and 0.55$^{0.56}_{0.53}$ for [OII] and H$\alpha$, respectively. Our resulting $f$-factors display a significant positive correlation with the UV attenuation and shallower or not-significant trends with the stellar mass, the $SFR_{\mathrm{TOT}}$, the distance to the main sequence, and the redshift. Finally, our results favour an average nebular attenuation curve similar in shape to the typical dust curve of local starbursts., Comment: 23 pages, 10 figures, 3 tables; accepted for publication in MNRAS

Galaxy mergers are thought to be one of the main mechanisms of the mass assembly of galaxies. Recently, many works have suggested a possible increase in the fraction of major mergers in the early Universe, reviving the debate on which processes (e.g., cold accretion, star formation, mergers) most contribute to the mass build-up of galaxies through cosmic time. To estimate the importance of major mergers in this context, we make use of the new data collected by the ALMA Large Program to INvestigate [CII] at Early times (ALPINE), which observed the [CII] 158 $\mu$m emission line from a sample of 75 main-sequence star-forming galaxies at 4.4 < z < 5.9. We used, for the first time, the morpho-kinematic information provided by the [CII] emission to obtain the fraction of major mergers ($f_{MM}$) at z~5. By adopting different prescriptions for the merger timescales ($T_{MM}$), we converted this fraction into the merger rate per galaxy ($R_{MM}$) and per volume ($\Gamma_{MM}$). We then combined our results with those at lower redshifts from the literature, computing the cosmic evolution of the merger fraction. This is described by a rapid increase from z~0 to higher redshifts, a peak at z~3, and a slow decrease towards earlier epochs. Depending on the timescale prescription used, this fraction translates into a merger rate ranging between ~0.1 and ~4.0 Gyr$^{-1}$ at z~5. Finally, we compare the specific star formation and star-formation rate density with the analogous quantities from major mergers. Our new ALPINE data reveal the presence of a significant merging activity in the early Universe. However, whether this population of mergers can provide a relevant contribution to the galaxy mass assembly at these redshifts and through the cosmic epochs is strongly dependent on the assumption of the merger timescale., Comment: Accepted for publication in section 4. Extragalactic astronomy of Astronomy and Astrophysics

The dust content of normal galaxies and the dust mass density (DMD) at high-z (z>4) are unconstrained given the source confusion and the sensitivity limitations of previous observations. The ALMA Large Program to INvestigate [CII] at Early Times (ALPINE), which targeted 118 UV-selected star-forming galaxies at 4.4

While the kinematics of galaxies up to z~3 have been characterized in detail, only a handful of galaxies at high redshift (z>4) have been examined in such a way. The Atacama Large Millimeter/submillimeter Array (ALMA) Large Program to INvestigate [CII] at Early times (ALPINE) survey observed a statistically significant sample of 118 star-forming main sequence galaxies at z=4.4-5.9 in [CII]158um emission, increasing the number of such observations by nearly 10x. A preliminary qualitative classification of these sources revealed a diversity of kinematic types (i.e., rotators, mergers, and dispersion-dominated systems). In this work, we supplement the initial classification by applying quantitative analyses to the ALPINE data: a tilted ring model (TRM) fitting code (3DBarolo), a morphological classification (Gini-M20), and a set of disk identification criteria. Of the 75 [CII]-detected ALPINE galaxies, 29 are detected at sufficient significance and spatial resolution to allow for TRM fitting and the derivation of morphological and kinematic parameters. These 29 sources constitute a high-mass subset of the ALPINE sample (M_*>10^9.5Msol). We robustly classify 14 of these sources (six rotators, five mergers, and three dispersion-dominated systems); the remaining sources showing complex behaviour. By exploring the G-M20 of z>4 rest-frame FIR and [CII] data for the first time, we find that our 1"~6kpc resolution data alone are insufficient to separate galaxy types. We compare the rotation curves and dynamical mass profiles of the six ALPINE rotators to the two previously detected z~4-6 unlensed main sequence rotators, finding high rotational velocities (~50-250km/s) and a diversity of rotation curve shapes., Comment: 25 pages, 15 figures. Accepted for publication in MNRAS

VANDELS is an ESO Public Spectroscopic Survey designed to build a sample of high signal to noise, medium resolution spectra of galaxies at redshift between 1 and 6.5. Here we present the final Public Data Release of the VANDELS Survey, comprising 2087 redshift measurements. We give a detailed description of sample selection, observations and data reduction procedures. The final catalogue reaches a target selection completeness of 40% at iAB = 25. The high Signal to Noise ratio of the spectra (above 7 in 80% of the spectra) and the dispersion of 2.5{\AA} allowed us to measure redshifts with high precision, the redshift measurement success rate reaching almost 100%. Together with the redshift catalogue and the reduced spectra, we also provide optical mid-IR photometry and physical parameters derived through SED fitting. The observed galaxy sample comprises both passive and star forming galaxies covering a stellar mass range 8.3< Log(M*/Msolar)<11.7. All catalogues and spectra are accessible through the survey database (http://vandels.inaf.it) where all information can be queried interactively, and via the ESO Archive (https://www.eso.org/qi/)., Comment: 16 pages, 13 figures, accepted for publication in Astronomy & Astrophysics

Utilizing spectroscopic observations taken for the VIMOS Ultra-Deep Survey (VUDS), new observations from Keck/DEIMOS, and publicly available observations of large samples of star-forming galaxies, we report here on the relationship between the star formation rate (SFR) and the local environment ($\delta_{gal}$) of galaxies in the early universe ($2

We study the co-evolution between the black hole accretion rate (BHAR) and the star formation rate (SFR) in different galaxy life phases: main sequence star-forming galaxies, quiescent and starburst galaxies at different cosmic epochs. We take advantage of the X-ray data from the Chandra COSMOS-Legacy survey and of the extensive multiwavelength ancillary observations in the COSMOS field presented in the COSMOS2015 catalog. We perform an X-ray stacking analysis and combine it with detected sources, in a broad redshift interval ($0.1

Star formation rate (SFR) measurements at z>4 have relied mostly on rest-frame far-ultraviolet (FUV) observations. The corrections for dust attenuation based on IRX-$\beta$ relation are highly uncertain and are still debated in the literature. Hence, rest-frame far-infrared (FIR) observations are necessary to constrain the dust-obscured component of the SFR. In this paper, we exploit the rest-frame FIR continuum observations collected by the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) to directly constrain the obscured SFR in galaxies at 4.4

The Lyman-$\alpha$ (Ly$\alpha$) emission line has been ubiquitously used to confirm and study high redshift galaxies. We report on the line morphology as seen in the 2D spectra from the VIMOS Ultra Deep Survey in a sample of 914 Ly$\alpha$ emitters from a parent sample of 4192 star-forming galaxies at $2

We present Atacama Large Millimeter/sub-millimeter Array (ALMA) observations towards 27 low-redshift ($0.02< z<0.2$) star-forming galaxies taken from the Valpara\'iso ALMA/APEX Line Emission Survey (VALES). We perform stacking analyses of the $^{12}$CO($1-0$), $^{13}$CO($1-0$) and C$^{18}$O($1-0$) emission lines to explore the $L'$ ($^{12}$CO($1-0$))/$L'$($^{13}$CO($1-0$))) (hereafter $L'$($^{12}$CO)/$L'$($^{13}$CO)) and $L'$($^{13}$CO($1-0$))/$L'$(C$^{18}$O($1-0$)) (hereafter $L'$($^{13}$CO)/$L'$(C$^{18}$O) line luminosity ratio dependence as a function of different global galaxy parameters related to the star formation activity. The sample has far-IR luminosities $10^{10.1-11.9}$L$_{\odot}$ and stellar masses of $10^{9.8-10.9}$M$_{\odot}$ corresponding to typical star-forming and starburst galaxies at these redshifts. On average we find a $L'$($^{12}$CO)/$L'$($^{13}$CO) line luminosity ratio value of 16.1$\pm$2.5. Galaxies with evidences of possible merging activity tend to show higher $L'$($^{12}$CO)/$L'$($^{13}$CO) ratios by a factor of two, while variations of this order are also found in galaxy samples with higher star formation rates or star formation efficiencies. We also find an average $L'$($^{13}$CO)/$L'$(C$^{18}$O) line luminosity ratio of 2.5$\pm$0.6, which is in good agreement with those previously reported for starburst galaxies. We find that galaxy samples with high $L_{\text{IR}}$, SFR and SFE show low $L'$($^{13}$CO)/$L'$(C$^{18}$O) line luminosity ratios with high $L'$($^{12}$CO)/$L'$($^{13}$CO) line luminosity ratios, suggesting that these trends are produced by selective enrichment of massive stars in young starbursts., Comment: 16 pages, 10 figures to be published in MNRAS

We present the detailed characterisation of a sample of 56 sources serendipitously detected in ALMA band 7, as part of the ALMA Large Program to INvestigate CII at Early Times (ALPINE) in COSMOS and ECDFS. These sources have been used to derive the total infrared luminosity function (LF) and to estimate the cosmic star formation rate density (SFRD) up to z=6. We have looked for counterparts in all the available multi-wavelength and photometric redshift catalogues, and in deeper near- and mid-IR source lists and maps, to identify optically dark sources with no matches in the public catalogues. Our ALMA blind survey allows us to push further the study of the nature and evolution of dusty galaxies at high-z, identifying luminous and massive sources to redshifts and faint luminosities never probed before by any far-infrared surveys. The ALPINE data are the first ones to sample the faint-end of the infrared LF, showing little evolution from z=2.5 to z=6, and a flat slope up to the highest redshifts. The SFRD obtained by integrating the luminosity function remains almost constant between z=2 and 6, and significantly higher than the optical/UV derivations, showing an important contribution of dusty galaxies and obscured star formation up to high-z. About 14 per cent of the ALPINE serendipitous continuum sources are optically+near-IR dark (six show a counterpart only in the mid-IR and no HST or near-IR identification, while two are detected as [CII] emitters at z=5). The six HST and near-IR dark galaxies with mid-IR counterpart contribute for about 17 per cent of the total SFRD at z=5 and dominate the high-mass end of the stellar mass function at z>3., Comment: 26 pages, 18 figures. Accepted for publication in A&A

We present the first [CII] 158 $\mu$m luminosity function (LF) at $z\sim 5$ from a sample of serendipitous lines detected in the ALMA Large Program to INvestigate [CII] at Early times (ALPINE). A search performed over 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 8 out of 14 detections as [CII] lines at $z\sim 5$, and two as CO transitions at lower redshifts. The remaining 4 lines have an elusive identification in the available catalogs and we considered them as [CII] candidates. We used the 8 confirmed [CII] and the 4 [CII] candidates to build one of the first [CII] LFs at $z\sim 5$. 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" sub-sample) according to their redshift separation and built two separate LFs. Our estimates suggest that there could be an evolution of the [CII] LF between $z \sim 5$ and $z \sim 0$. By converting the [CII] luminosity to star formation rate we evaluated the cosmic star formation rate density (SFRD) at $z\sim 5$. The clustered sample results in a SFRD $\sim 10$ 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 $\sim 1.6$ higher compared to current estimates from UV surveys but compatible within the errors. Because of the large uncertainties, observations of larger samples are necessary to better constrain the SFRD at $z\sim 5$. This study represents one of the first efforts aimed at characterizing the demography of [CII] emitters at $z\sim 5$ using a mm-selection of galaxies., Comment: 19 pages, 12 figures; submitted to Astronomy & Astrophysics

We present the [CII]158$\mu$m line luminosity functions (LFs) at $z\sim4-6$ using the ALMA observations of 118 sources, which are selected to have UV luminosity $M_{1500A}<-20.2$ and optical spectroscopic redshifts in COSMOS and ECDF-S. Of the 118 targets, 75 have significant [CII] detections and 43 are upper limits. This is by far the largest sample of [CII] detections which allows us to set constraints to the volume density of [CII] emitters at $z\sim4-6$. But because this is a UV-selected sample, we are missing [CII]-bright but UV-faint sources making our constraints strict lower limits. Our derived LFs are statistically consistent with the $z\sim0$ [CII] LF at $10^{8.25} - 10^{9.75}L_\odot$. We compare our results with the upper limits of the [CII] LF derived from serendipitous sources in the ALPINE maps (Loiacono et al. 2020). We also infer the [CII] LFs based on published far-IR and CO LFs at $z\sim4-6$. Combining our robust lower limits with these additional estimates, we set further constraints to the true number density of [CII] emitters at $z\sim 4 - 6$. These additional LF estimates are largely above our LF at $L_{[CII]}>10^9L_{\odot}$, suggesting that UV-faint but [CII]-bright sources likely make a significant contributions to the [CII] emitter volume density. When we include all the LF estimates, we find that available model predictions underestimate the number densities of [CII] emitters at $z\sim4-6$. Finally, we set a constraint on the molecular gas mass density at $z\sim4-6$, with $\rho_{mol} \sim (2-7)\times10^7M_\odot$\,Mpc$^{-3}$. This is broadly consistent with previous studies., Comment: 17 pages, 9 Figures, Update to match with the published version. Accepted for the publication in ApJ

We present ALMA observations of a merging system at z ~ 4.57, observed as a part of the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) survey. Combining ALMA [CII] 158 micron and far-infrared continuum data with multi-wavelength ancillary data we find that the system is composed of two massive (Mstar >~ 10^10 Msun) star-forming galaxies experiencing a major merger (stellar mass ratio r_mass ~ 0.9) at close spatial (~13 kpc; projected) and velocity (delta_v < 300 km/s) separations, and two additional faint narrow [CII]-emitting satellites. The overall system belongs to a larger-scale protocluster environment and is coincident to one of its overdensity peaks. ALMA reveals also the presence of [CII] emission arising from a circumgalactic gas structure, extending up to a diameter-scale of ~30 kpc. Our morpho-spectral decomposition analysis shows that about 50% of the total flux resides between the individual galaxy components, in a metal-enriched gaseous envelope characterized by a disturbed morphology and complex kinematics. Similarly to observations of shock-excited [CII] emitted from tidal tails in local groups, our results can be interpreted as a possible signature of interstellar gas stripped by strong gravitational interactions, with a possible contribution from material ejected by galactic outflows and emission triggered by star formation in small faint satellites. Our findings suggest that mergers could be an efficient mechanism of gas mixing in the circumgalactic medium around high-z galaxies, and thus play a key role in the galaxy baryon cycle at early epochs., Comment: 12 pages, 7 figures. Accepted for publication in A&A

The molecular gas content of normal galaxies at z>4 is poorly constrained, because the commonly used molecular gas tracers become hard to detect. We use the [CII]158um luminosity, recently proposed as a molecular gas tracer, to estimate the molecular gas content in a large sample of main-sequence star-forming galaxies at z=4.4-5.9, with a median stellar mass of 10^9.7 Msun, drawn from the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) survey. The agreement between molecular gas masses derived from [CII] luminosity, dynamical mass, and rest-frame 850um luminosity, extrapolated from the rest-frame 158um continuum, supports [CII] as a reliable tracer of molecular gas in our sample. We find a continuous decline of the molecular gas depletion timescale from z=0 to z=5.9, which reaches a mean value of (4.6+/-0.8)x10^8 yr at z~5.5, only a factor of 2-3 shorter than in present-day galaxies. This suggests a mild enhancement of star formation efficiency toward high redshifts, unless the molecular gas fraction significantly increases. Our estimates show that the rise in molecular gas fraction as reported previously, flattens off above z~3.7 to achieve a mean value of 63%+/-3 over z=4.4-5.9. This redshift evolution of the gas fraction is in line with the one of the specific star formation rate. We use multi-epoch abundance matching to follow the gas fraction evolution over cosmic time of progenitors of z=0 Milky Way-like galaxies in 10^13 Msun halos and of more massive z=0 galaxies in 10^14 Msun halos. Interestingly, the former progenitors show a monotonic decrease of the gas fraction with cosmic time, while the latter show a constant gas fraction from z=5.9 to z~2 and a decrease at z<2. We discuss three possible effects, namely outflows, halt of gas supplying, and over-efficient star formation, which may jointly contribute to the gas fraction plateau of the latter massive galaxies., Comment: 16 pages, 9 figures, 2 tables. Submitted to Astronomy & Astrophysics

We present dust attenuation properties of spectroscopically confirmed star forming galaxies on the main sequence at a redshift of ~4.4-5.8. Our analyses are based on the far infrared continuum observations of 118 galaxies at rest-frame 158{\mu}m obtained with the Atacama Large Millimeter Array (ALMA) Large Program to INvestigate [CII] at Early times (ALPINE). We study the connection between the ultraviolet (UV) spectral slope ($\beta$), stellar mass (M_*), and infrared excess (IRX=L_IR/L_UV). Twenty-three galaxies are individually detected in the continuum at >3.5 sigma significance. We perform a stacking analysis using both detections and nondetections to study the average dust attenuation properties at z~4.4-5.8. The individual detections and stacks show that the IRX-$\beta$ relation at z~5 is consistent with a steeper dust attenuation curve than typically found at lower redshifts (z<4). The attenuation curve is similar to or even steeper than that of the extinction curve of the Small Magellanic Cloud (SMC). This systematic change of the IRX-$\beta$ relation as a function of redshift suggests an evolution of dust attenuation properties at z>4. Similarly, we find that our galaxies have lower IRX values, up to 1dex on average, at a fixed mass compared to previously studied IRX-M_* relations at z<4, albeit with significant scatter. This implies a lower obscured fraction of star formation than at lower redshifts. Our results suggest that dust properties of UV-selected star forming galaxies at z>4 are characterised by (i) a steeper attenuation curve than at z<4, and (ii) a rapidly decreasing dust obscured fraction of star formation as a function of redshift. Nevertheless, even among this UV-selected sample, massive galaxies (log M_*/$M_\odot$>10) at z~5-6 already exhibit an obscured fraction of star formation of ~45%, indicating a rapid build-up of dust during the epoch of reionization., Comment: 12 pages, 6 figures. accepted for publication in Astronomy & Astrophysics. Minor revisions

In the second work of this series, we analyse the connection between the availability of gas and the position of a region with respect to the spatially resolved main sequence (MS) relation. Following the procedure presented in Paper I we obtain 500pc scales estimates of stellar mass and star formation rate surface densities ($\Sigma_{\star}$ and $\Sigma_{\rm{SFR}}$). Our sample consists of five face-on, grand design spiral galaxies located on the MS. Thanks to HI 21cm and $^{12}$CO(2-1) maps, we connect the gas surface densities and gas fractions to the observed star formation properties of each region. We find that the spatially resolved MS ($\sigma=0.23$ dex) is the combination of two relations: the Kennicutt-Schmidt law ($\sigma=0.19$ dex) and the molecular gas MS (MGMS, $\sigma=0.22$ dex); $\Sigma_{\star}$, $\Sigma_{\rm{SFR}}$ and the surface density of the molecular gas, $\Sigma_{\rm{H_2}}$, define a 3D relation as proposed by \citet{2019ApJ...884L..33L}. We find that $\Sigma_{\rm{H_2}}$ steadily increases along the MS relation, varies little towards higher $\Sigma_{\rm{SFR}}$ at fixed stellar surface densities (not enough to sustain the change in SFR), and it is almost constant perpendicular to the relation. The surface density of neutral gas ($\Sigma_{\rm{HI}}$) is constant along the MS, and increases in its upper envelop. $\Sigma_{\rm{SFR}}$ can be expressed as a function of $\Sigma_{\star}$ and $\Sigma_{\rm{HI}}$, following the Equation: $\log\Sigma_{\rm{SFR}}$ = 0.97$\log\Sigma_{\star}$ + 1.99$\log\Sigma_{\rm{HI}}$ - 11.11. Finally, we show that f$_{\rm{gas}}$ increases significantly towards the starburst region in the $\log\Sigma_{\star}$ - $\log\Sigma_{\rm{SFR}}$ plane, accompanied by a slight increase in SFE., Comment: Accepted for publications on MNRAS

We present the physical extent of [CII] 158um line-emitting gas from 46 star-forming galaxies at z=4-6 from the ALMA Large Program to INvestigate CII at Early Times (ALPINE). Using exponential profile fits, we measure the effective radius of the [CII] line (r_e,[CII]) for individual galaxies and compare them with the rest-frame ultra-violet (UV) continuum (r_e,UV) from Hubble Space Telescope images. The effective radius r_e,[CII] exceeds r_e,UV by factors of ~2-3 and the ratio of r_e,[CII]/r_e,UV increases as a function of M_star. We do not find strong evidence that [CII] line, the rest-frame UV, and FIR continuum are always displaced over ~ 1-kpc scale from each other. We identify 30% of isolated ALPINE sources as having an extended [CII] component over 10-kpc scales detected at 4.1$\sigma$-10.9$\sigma$ beyond the size of rest-frame UV and far-infrared (FIR) continuum. One object has tentative rotating features up to ~10-kpc, where the 3D model fit shows the rotating [CII]-gas disk spread over 4 times larger than the rest-frame UV-emitting region. Galaxies with the extended [CII] line structure have high star-formation rate (SFR), stellar mass (M_star), low Lya equivalent-width, and more blue-shifted (red-shifted) rest-frame UV metal absorption (Lya line), as compared to galaxies without such extended [CII] structures. Although we cannot rule out the possibility that a selection bias towards luminous objects may be responsible for such trends, the star-formation driven outflow also explains all these trends. Deeper observations are essential to test whether the extended [CII] line structures are ubiquitous to high-z star-forming galaxies., Comment: 21 pages, 11 figures, ApJ in press

We present the detection of CO(5-4) with S/N> 7 - 13 and a lower CO transition with S/N > 3 (CO(4-3) for 4 galaxies, and CO(3-2) for one) with ALMA in band 3 and 4 in five main sequence star-forming galaxies with stellar masses 3-6x10^10 M/M_sun at 3 < z < 3.5. We find a good correlation between the total far-infrared luminosity LFIR and the luminosity of the CO(5-4) transition L'CO(5-4), where L'CO(5-4) increases with SFR, indicating that CO(5-4) is a good tracer of the obscured SFR in these galaxies. The two galaxies that lie closer to the star-forming main sequence have CO SLED slopes that are comparable to other star-forming populations, such as local SMGs and BzK star-forming galaxies; the three objects with higher specific star formation rates (sSFR) have far steeper CO SLEDs, which possibly indicates a more concentrated episode of star formation. By exploiting the CO SLED slopes to extrapolate the luminosity of the CO(1-0) transition, and using a classical conversion factor for main sequence galaxies of alpha_CO = 3.8 M_sun(K km s^-1 pc^-2)^-1, we find that these galaxies are very gas rich, with molecular gas fractions between 60 and 80%, and quite long depletion times, between 0.2 and 1 Gyr. Finally, we obtain dynamical masses that are comparable with the sum of stellar and gas mass (at least for four out of five galaxies), allowing us to put a first constraint on the alpha_CO parameter for main sequence galaxies at an unprecedented redshift., Comment: 17 pages, 8 figures; accepted for publication in The Astrophysical Journal

The [CII] 158 micron line is one of the strongest IR emission lines, which has been shown to trace the star-formation rate (SFR) of galaxies in the nearby Universe and up to $z \sim 2$. Whether this is also the case at higher redshift and in the early Universe remains debated. The ALPINE survey, which targeted 118 star-forming galaxies at $4.4 < z< 5.9$, provides a new opportunity to examine this question with the first statistical dataset. Using the ALPINE data and earlier measurements from the literature we examine the relation between the [CII] luminosity and the SFR over the entire redshift range from $z \sim 4-8$. ALPINE galaxies, which are both detected in [CII] and dust continuum, show a good agreement with the local L([CII])-SFR relation. Galaxies undetected in the continuum with ALMA are found to be over-luminous in [CII], when the UV SFR is used. After accounting for dust-obscured star formation, by an amount SFR(IR)$\approx$SFR(UV) on average, which results from two different stacking methods and SED fitting, the ALPINE galaxies show an L([CII])-SFR relation comparable to the local one. When [CII] non-detections are taken into account, the slope may be marginally steeper at high-z, although this is still somewhat uncertain. When compared in a homogeneous manner, the $z>6 $ [CII] measurements (detections and upper limits) do not behave very differently from the $z \sim 4-6$ data. We find a weak dependence of L([CII])/SFR on the Lyman-alpha equivalent width. Finally, we find that the ratio L([CII])/LIR $\sim (1-3) \times 10^{-3}$ for the ALPINE sources, comparable to that of "normal" galaxies at lower redshift. Our analysis, which includes the largest sample ($\sim 150$ galaxies) of [CII] measurements at $z>4$ available so far, suggests no or little evolution of the L([CII])-SFR relation over the last 13 Gyr of cosmic time., Comment: 11 pages, 7 figures. Accepted for publication in Astronomy & Astrophysics. Minor revisions, see e.g. Table A.1

The ALPINE-ALMA large program targets the [CII] 158 $\mu$m line and the far-infrared continuum in 118 spectroscopically confirmed star-forming galaxies between z=4.4 and z=5.9. It represents the first large [CII] statistical sample built in this redshift range. We present details of the data processing and the construction of the catalogs. We detected 23 of our targets in the continuum. To derive accurate infrared luminosities and obscured star formation rates, we measured the conversion factor from the ALMA 158 $\mu$m rest-frame dust continuum luminosity to the total infrared luminosity (L$_{\rm IR}$) after constraining the dust spectral energy distribution by stacking a photometric sample similar to ALPINE in ancillary single-dish far-infrared data. We found that our continuum detections have a median L$_{\rm IR}$ of 4.4$\times 10^{11}$ L$_\odot$. We also detected 57 additional continuum sources in our ALMA pointings. They are at lower redshift than the ALPINE targets, with a mean photometric redshift of 2.5$\pm$0.2. We measured the 850 $\mu$m number counts between 0.35 and 3.5 mJy, improving the current interferometric constraints in this flux density range. We found a slope break in the number counts around 3 mJy with a shallower slope below this value. More than 40 % of the cosmic infrared background is emitted by sources brighter than 0.35 mJy. Finally, we detected the [CII] line in 75 of our targets. Their median [CII] luminosity is 4.8$\times$10$^8$ L$_\odot$ and their median full width at half maximum is 252 km/s. After measuring the mean obscured SFR in various [CII] luminosity bins by stacking ALPINE continuum data, we find a good agreement between our data and the local and predicted SFR-L$_{\rm [CII]}$ relations of De Looze et al. (2014) and Lagache et al. (2018)., Comment: 44 pages, 29 figures, 14 tables, accepted by A&A, ALPINE products released at https://cesam.lam.fr/a2c2s/, luminosities in table B2 corrected

The Lya line in the UV and the [CII] line in the FIR are widely used tools to identify galaxies and to obtain insights into ISM properties in the early Universe. By combining data obtained with ALMA in band 7 at ~ 320 GHz as part of the ALMA Large Program to INvestigate [CII] at Early Times (ALPINE) with spectroscopic data from DEIMOS at Keck, VIMOS and FORS2 at the VLT, we assembled a unique sample of 53 main-sequence star-forming galaxies at 4.4 < z < 6 in which we detect both the Lya line and the [CII]. We used [CII], observed with ALMA, as a tracer of the systemic velocity of the galaxies, and we find that 90% of the selected objects have Lya-[CII] velocity offsets in the range 0 < Dv_Lya-[CII] < 400 km/s, in line with the few measurements available so far in the early Universe, and significantly smaller than those observed at lower z. We observe ISM-[CII] offsets in the range -500 < Dv_ISM-[CII] < 0 km/s, in line with values at all redshifts. We find significant anticorrelations between Dv_Lya-[CII] and the Lya rest-frame equivalent width EW0(Lya) (or equivalently, the Lya escape fraction f_esc(Lya)). According to available models for the radiative transfer of Lya photons, the escape of Lya photons would be favored in galaxies with high outflow velocities, in agreement with our observations. The uniform shell model would also predict that the Lya escape in galaxies with slow outflows (0 < v_out < 300 km/s) is mainly determined by the neutral hydrogen column density (NHI), while the alternative model by Steidel+10 would favor a combination of NHI and covering fraction as driver of the Lya escape. We suggest that the observed increase in Lya escape that is observed between z~2 and z~6 is not due to a higher incidence of fast outflows at high redshift, but rather to a decrease in average NHI along the line of sight, or alternatively, a decrease in HI covering fraction. [abridged], Comment: 22 pages, 6 figures, accepted for publication in A&A. This version replaces the previous one