arXiv subjects

A. Cimatti

Publications and source records attributed to A. Cimatti.

At least 289 records · Page 16Linked to original sources

arXiv2021

Euclid: Forecasts for $k$-cut $3 \times 2$ Point Statistics

Modelling uncertainties at small scales, i.e. high $k$ in the power spectrum $P(k)$, due to baryonic feedback, nonlinear structure growth and the fact that galaxies are biased tracers poses a significant obstacle to fully leverage the constraining power of the {\it Euclid} wide-field survey. $k$-cut cosmic shear has recently been proposed as a method to optimally remove sensitivity to these scales while preserving usable information. In this paper we generalise the $k$-cut cosmic shear formalism to $3 \times 2$ point statistics and estimate the loss of information for different $k$-cuts in a $3 \times 2$ point analysis of the {\it Euclid} data. Extending the Fisher matrix analysis of~\citet{blanchard2019euclid}, we assess the degradation in constraining power for different $k$-cuts. We work in the idealised case and assume the galaxy bias is linear, the covariance is Gaussian, while neglecting uncertainties due to photo-z errors and baryonic feedback. We find that taking a $k$-cut at $2.6 \ h \ {\rm Mpc} ^{-1}$ yields a dark energy Figure of Merit (FOM) of 1018. This is comparable to taking a weak lensing cut at $\ell = 5000$ and a galaxy clustering and galaxy-galaxy lensing cut at $\ell = 3000$ in a traditional $3 \times 2$ point analysis. We also find that the fraction of the observed galaxies used in the photometric clustering part of the analysis is one of the main drivers of the FOM. Removing $50 \% \ (90 \%)$ of the clustering galaxies decreases the FOM by $19 \% \ (62 \%)$. Given that the FOM depends so heavily on the fraction of galaxies used in the clustering analysis, extensive efforts should be made to handle the real-world systematics present when extending the analysis beyond the luminous red galaxy (LRG) sample.

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arXiv2021

HST grism spectroscopy of z~3 massive quiescent galaxies: Approaching the metamorphosis

Tracing the emergence of the massive quiescent galaxy (QG) population requires the build-up of reliable quenched samples. We present Hubble Space Telescope WFC3/G141 grism spectra of 10 quiescent galaxy candidates selected at $2.5<z<3.5$ in the COSMOS field. Spectroscopic confirmation for the whole sample is obtained within 1-3 orbits based on the presence of strong spectral breaks and Balmer absorption lines. Combining their spectra with optical to near-IR photometry, star-forming solutions are formally rejected for the entire sample. Broad spectral indices are consistent with the presence of young A-type stars, which implies that the last major episode of star formation has taken place no earlier than $\sim$300-800 Myr prior to observation. Marginalising over three different slopes of the dust attenuation curve, we obtain short mass-weighted ages and an average peak star formation rate of SFR$\sim10^3$ M$_{\odot}$ yr$^{-1}$ at $z_{formation}\sim3.5$. Despite mid- and far-IR data are too shallow to determine the obscured SFR on a galaxy-by-galaxy basis, the mean stack emission from 3GHz data constrains the level of residual obscured SFR to be globally below 50 M$_{\odot}$ yr$^{-1}$, hence three times below the scatter of the coeval main sequence. Alternatively, the very same radio detection suggests a widespread radio-mode feedback by active galactic nuclei (AGN) four times stronger than in z$\sim$1.8 massive QGs. This is accompanied by a 30% fraction of X-ray luminous AGN with a black hole accretion rate per unit SFR enhanced by a factor of $\sim30$ with respect to similarly massive QGs at lower redshift. The average compact, high Sérsic index morphologies of our galaxies, coupled with their young mass-weighted ages, suggest that the mechanisms responsible for the development of a spheroidal component might be concomitant with (or preceding) those causing their quenching.

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arXiv2021

The ALPINE-ALMA [CII] survey: Dust mass budget in the early Universe

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<z<5.9, provides a new opportunity to tackle this issue for the first time with a statistically robust dataset. We have exploited the rest-frame far-infrared (FIR) fluxes of the 23 continuum individually detected galaxies and stacks of continuum images to measure the dust content of the 118 UV-selected ALPINE galaxies. We have focused on the dust scaling relations and, by comparing them with predictions from chemical evolution models, we have probed the evolutionary stage of UV-selected galaxies at high-z. By using the observed correlation between the UV-luminosity and the dust mass, we have estimated the DMD of UV-selected galaxies at z~5, weighting the galaxies by means of the UV-luminosity function (UVLF). The derived DMD has been compared with the value we have estimated from the 10 ALPINE far-IR continuum blindly detected galaxies at the redshift of the ALPINE targets. The comparison of the observed dust scaling relations with chemical evolution models suggests that ALPINE galaxies are not likely progenitors of disc galaxies, but of intermediate and low mass proto-spheroids, resulting in present-day bulges of spiral or elliptical galaxies. Interestingly, this conclusion is in line with the independent morphological analysis, that shows that the majority (~70\%) of the dust-continuum detected galaxies have a disturbed morphology. The DMD obtained at z~5 from UV-selected sources is ~30% of the value obtained from blind far-IR selected sources, showing that the UV-selection misses the most dust-rich, UV-obscured galaxies.

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arXiv2021

Euclid: constraining dark energy coupled to electromagnetism using astrophysical and laboratory data

In physically realistic scalar-field based dynamical dark energy models (including, e.g., quintessence) one naturally expects the scalar field to couple to the rest of the model's degrees of freedom. In particular, a coupling to the electromagnetic sector leads to a time (redshift) dependence of the fine-structure constant and a violation of the Weak Equivalence Principle. Here we extend the previous Euclid forecast constraints on dark energy models to this enlarged (but physically more realistic) parameter space, and forecast how well Euclid, together with high-resolution spectroscopic data and local experiments, can constrain these models. Our analysis combines simulated Euclid data products with astrophysical measurements of the fine-structure constant, $α$, and local experimental constraints, and includes both parametric and non-parametric methods. For the astrophysical measurements of $α$ we consider both the currently available data and a simulated dataset representative of Extremely Large Telescope measurements and expected to be available in the 2030s. Our parametric analysis shows that in the latter case the inclusion of astrophysical and local data improves the Euclid dark energy figure of merit by between $8\%$ and $26\%$, depending on the correct fiducial model, with the improvements being larger in the null case where the fiducial coupling to the electromagnetic sector is vanishing. These improvements would be smaller with the current astrophysical data. Moreover, we illustrate how a genetic algorithms based reconstruction provides a null test for the presence of the coupling. Our results highlight the importance of complementing surveys like Euclid with external data products, in order to accurately test the wider parameter spaces of physically motivated paradigms.

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arXiv2021

The NIRVANDELS Survey: a robust detection of $α$-enhancement in star-forming galaxies at $z\simeq3.4$

We present results from the NIRVANDELS survey investigating the gas-phase metallicity ($\mathrm{Z}_{\mathrm{gas}}$, tracing O/H) and stellar metallicity ($Z_{\star}$, tracing Fe/H) of 33 star-forming galaxies at redshifts $2.95 < z < 3.80$. Based on a combined analysis of deep optical and near-IR spectra, tracing the rest-frame far ultraviolet and rest-frame optical respectively, we present the first simultaneous determination of the stellar and gas-phase mass-metallicity relationships (MZRs) at $z\simeq3.4$. In both cases, we find that metallicity increases with increasing stellar mass ($M_{\star}$), and that the power-law slope at $M_{\star} \lesssim 10^{10} \mathrm{M}_{\odot}$ of both MZRs scales as $Z \propto M_{\star}^{0.3}$. Comparing the stellar and gas-phase MZRs, we present direct evidence for super-solar O/Fe ratios (i.e., $α$-enhancement) at $z>3$, finding $\mathrm{(O/Fe)}\simeq (2.54 \pm 0.38) \times \mathrm{(O/Fe)}_{\odot}$, with no clear dependence on $M_{\star}$.

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arXiv2021

Euclid: Estimation of the impact of correlated readout noise for flux measurements with the Euclid NISP instrument

The Euclid satellite, to be launched by ESA in 2022, will be a major instrument for cosmology for the next decades. \Euclid\ is composed of two instruments: the Visible (VIS) instrument and the Near Infrared Spectromete and Photometer (NISP). In this work we estimate the implications of correlated readout noise in the NISP detectors for the final in-flight flux measurements. Considering the multiple accumulated (MACC) readout mode, for which the UTR (Up The Ramp) exposure frames are averaged in groups, we derive an analytical expression for the noise covariance matrix between groups in the presence of correlated noise. We also characterize the correlated readout noise properties in the NISP engineering grade detectors using long dark integrations. For this purpose, we assume a $(1/f)^{\, α}$-like noise model and fit the model parameters to the data, obtaining typical values of $σ= 19.7^{+1.1}_{-0.8}$ e$^{-} \rm{Hz}^{-0.5}$, $f_{\rm{knee}} = (5.2^{+1.8}_{-1.3}) \times 10^{-3} \, \rm{Hz}$ and $α= 1.24 ^{+0.26}_{-0.21}$. Furthermore, via realistic simulations and using a maximum likelihood flux estimator we derive the bias between the input flux and the recovered one. We find that using our analytical expression for the covariance matrix of the correlated readout noise we diminish this bias by up to a factor of four with respect to the white noise approximation for the covariance matrix. Finally, we conclude that the final bias on the in-flight NISP flux measurements should still be negligible even in the white noise approximation, which is taken as a baseline for the Euclid\on-board processing

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arXiv2021

Euclid preparation: XII. Optimizing the photometric sample of the Euclid survey for galaxy clustering and galaxy-galaxy lensing analyses

The accuracy of photometric redshifts (photo-zs) particularly affects the results of the analyses of galaxy clustering with photometrically-selected galaxies (GCph) and weak lensing. In the next decade, space missions like Euclid will collect photometric measurements for millions of galaxies. These data should be complemented with upcoming ground-based observations to derive precise and accurate photo-zs. In this paper, we explore how the tomographic redshift binning and depth of ground-based observations will affect the cosmological constraints expected from Euclid. We focus on GCph and extend the study to include galaxy-galaxy lensing (GGL). We add a layer of complexity to the analysis by simulating several realistic photo-z distributions based on the Euclid Consortium Flagship simulation and using a machine learning photo-z algorithm. We use the Fisher matrix formalism and these galaxy samples to study the cosmological constraining power as a function of redshift binning, survey depth, and photo-z accuracy. We find that bins with equal width in redshift provide a higher Figure of Merit (FoM) than equipopulated bins and that increasing the number of redshift bins from 10 to 13 improves the FoM by 35% and 15% for GCph and its combination with GGL, respectively. For GCph, an increase of the survey depth provides a higher FoM. But the addition of faint galaxies beyond the limit of the spectroscopic training data decreases the FoM due to the spurious photo-zs. When combining both probes, the number density of the sample, which is set by the survey depth, is the main factor driving the variations in the FoM. We conclude that there is more information that can be extracted beyond the nominal 10 tomographic redshift bins of Euclid and that we should be cautious when adding faint galaxies into our sample, since they can degrade the cosmological constraints.

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arXiv2021

The less and the more IGM transmitted galaxies from z~2.7 to z~6 from VANDELS and VUDS

Aim. Our aim is to analyse the variance of the Inter-Galactic Medium transmission (IGM) by studying this parameter in the rest-frame UV spectra of a large sample of high redshift galaxies. Method. We make use of the VIMOS Ultra Deep Survey and the VANDELS public survey to have an insight into the far UV spectrum of $2.7<z<6$ galaxies. Using the SPARTAN fitting software, we estimate the IGM towards individual galaxies and then divide them in two sub-samples characterized by a transmission above or below the theoretical prescription. We create average spectra of combined VUDS and VANDELS data for each set of galaxies in seven redshift bins. Results. The resulting spectra clearly exhibit the variance of the IGM transmission that can be seen directly from high redshift galaxy observations. Computing the optical depth based on the IGM transmission, we find an excellent agreement with QSOs results. In addition, our measurements seem to suggest that there is a large dispersion of redshift where complete Gunn-Peterson Trough happens, depending on the line of sight.

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arXiv2021

Euclid: Effect of sample covariance on the number counts of galaxy clusters

Aims. We investigate the contribution of shot-noise and sample variance to the uncertainty of cosmological parameter constraints inferred from cluster number counts in the context of the Euclid survey. Methods. By analysing 1000 Euclid-like light-cones, produced with the PINOCCHIO approximate method, we validate the analytical model of Hu & Kravtsov 2003 for the covariance matrix, which takes into account both sources of statistical error. Then, we use such covariance to define the likelihood function that better extracts cosmological information from cluster number counts at the level of precision that will be reached by the future Euclid photometric catalogs of galaxy clusters. We also study the impact of the cosmology dependence of the covariance matrix on the parameter constraints. Results. The analytical covariance matrix reproduces the variance measured from simulations within the 10 per cent level; such difference has no sizeable effect on the error of cosmological parameter constraints at this level of statistics. Also, we find that the Gaussian likelihood with cosmology-dependent covariance is the only model that provides an unbiased inference of cosmological parameters without underestimating the errors.

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arXiv2021

The VANDELS ESO public spectroscopic survey: final Data Release of 2087 spectra and spectroscopic measurements

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 2.5Å 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/).

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arXiv2021

Euclid preparation: XI. Mean redshift determination from galaxy redshift probabilities for cosmic shear tomography

The analysis of weak gravitational lensing in wide-field imaging surveys is considered to be a major cosmological probe of dark energy. Our capacity to constrain the dark energy equation of state relies on the accurate knowledge of the galaxy mean redshift $\langle z \rangle$. We investigate the possibility of measuring $\langle z \rangle$ with an accuracy better than $0.002\,(1+z)$, in ten tomographic bins spanning the redshift interval $0.2 99.8\%$. The zPDF approach could also be successful if we debias the zPDF using a spectroscopic training sample. This approach requires deep imaging data, but is weakly sensitive to spectroscopic redshift failures in the training sample. We improve the debiasing method and confirm our finding by applying it to real-world weak-lensing data sets (COSMOS and KiDS+VIKING-450).

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arXiv2020

Euclid preparation: VII. Forecast validation for Euclid cosmological probes

The Euclid space telescope will measure the shapes and redshifts of galaxies to reconstruct the expansion history of the Universe and the growth of cosmic structures. Estimation of the expected performance of the experiment, in terms of predicted constraints on cosmological parameters, has so far relied on different methodologies and numerical implementations, developed for different observational probes and for their combination. In this paper we present validated forecasts, that combine both theoretical and observational expertise for different cosmological probes. This is presented to provide the community with reliable numerical codes and methods for Euclid cosmological forecasts. We describe in detail the methodology adopted for Fisher matrix forecasts, applied to galaxy clustering, weak lensing and their combination. We estimate the required accuracy for Euclid forecasts and outline a methodology for their development. We then compare and improve different numerical implementations, reaching uncertainties on the errors of cosmological parameters that are less than the required precision in all cases. Furthermore, we provide details on the validated implementations that can be used by the reader to validate their own codes if required. We present new cosmological forecasts for Euclid. We find that results depend on the specific cosmological model and remaining freedom in each setup, i.e. flat or non-flat spatial cosmologies, or different cuts at nonlinear scales. The validated numerical implementations can now be reliably used for any setup. We present results for an optimistic and a pessimistic choice of such settings. We demonstrate that the impact of cross-correlations is particularly relevant for models beyond a cosmological constant and may allow us to increase the dark energy Figure of Merit by at least a factor of three.

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arXiv2020

Euclid preparation: X. The Euclid photometric-redshift challenge

Forthcoming large photometric surveys for cosmology require precise and accurate photometric redshift (photo-z) measurements for the success of their main science objectives. However, to date, no method has been able to produce photo-$z$s at the required accuracy using only the broad-band photometry that those surveys will provide. An assessment of the strengths and weaknesses of current methods is a crucial step in the eventual development of an approach to meet this challenge. We report on the performance of 13 photometric redshift code single value redshift estimates and redshift probability distributions (PDZs) on a common set of data, focusing particularly on the 0.2--2.6 redshift range that the Euclid mission will probe. We design a challenge using emulated Euclid data drawn from three photometric surveys of the COSMOS field. The data are divided into two samples: one calibration sample for which photometry and redshifts are provided to the participants; and the validation sample, containing only the photometry, to ensure a blinded test of the methods. Participants were invited to provide a redshift single value estimate and a PDZ for each source in the validation sample, along with a rejection flag that indicates sources they consider unfit for use in cosmological analyses. The performance of each method is assessed through a set of informative metrics, using cross-matched spectroscopic and highly-accurate photometric redshifts as the ground truth. We show that the rejection criteria set by participants are efficient in removing strong outliers, sources for which the photo-z deviates by more than 0.15(1+z) from the spectroscopic-redshift (spec-z). We also show that, while all methods are able to provide reliable single value estimates, several machine-learning methods do not manage to produce useful PDZs. [abridged]

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arXiv2020

The VANDELS survey: the relation between UV continuum slope and stellar metallicity in star-forming galaxies at z~3

The estimate of stellar metallicities (Z*) of high-z galaxies are of paramount importance in order to understand the complexity of dust effects and the reciprocal interrelations among stellar mass, dust attenuation, stellar age, and metallicity. Benefiting from uniquely deep FUV spectra of >500 star-forming galaxies at redshifts 2<z<5 extracted from the VANDELS survey and stacked in bins of stellar mass (M*) and UV continuum slope (beta), we estimate their stellar metallicities Z* from stellar photospheric absorption features at 1501 and 1719 Angstrom, which are calibrated with Starburst99 models and are largely unaffected by stellar age, dust, IMF, nebular continuum or interstellar absorption. Comparing them to photometric based spectral slopes in the range 1250-1750 Angstrom, we find that the stellar metallicity increases by ~0.5 dex from beta ~ -2 to beta ~ -1 (1 < A(1600) < 3.2), and a dependence with beta holds at fixed UV absolute luminosity M(UV) and stellar mass up to 10^(9.65) Msun. As a result, the metallicity is a fundamental ingredient for properly rescaling dust corrections based on M(UV) and M*. Using the same absorption features, we analyze the mass-metallicity relation (MZR) and find it is consistent with the previous VANDELS estimation based on a global fit of the FUV spectra. Similarly, we do not find a significant evolution between z=2 and z=3.5. Finally, the slopes of our MZR and Z*-beta relation are in agreement with the predictions of well-studied semi-analytic models of galaxy formation (SAM), while some tensions with observations remain as to the absolute metallicity normalization. The relation between UV slope and stellar metallicity is fundamental for the exploitation of large volume surveys with next-generation telescopes and for the physical characterization of galaxies in the first billion years of our Universe.

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arXiv2020

The ALPINE-ALMA [C II] Survey: [C II]158micron Emission Line Luminosity Functions at $z \sim 4-6$

We present the [CII]158$μ$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 $ρ_{mol} \sim (2-7)\times10^7M_\odot$\,Mpc$^{-3}$. This is broadly consistent with previous studies.

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arXiv2020

Euclid: impact of nonlinear prescriptions on cosmological parameter estimation from weak lensing cosmic shear

Upcoming surveys will map the growth of large-scale structure with unprecented precision, improving our understanding of the dark sector of the Universe. Unfortunately, much of the cosmological information is encoded by the small scales, where the clustering of dark matter and the effects of astrophysical feedback processes are not fully understood. This can bias the estimates of cosmological parameters, which we study here for a joint analysis of mock Euclid cosmic shear and Planck cosmic microwave background data. We use different implementations for the modelling of the signal on small scales and find that they result in significantly different predictions. Moreover, the different nonlinear corrections lead to biased parameter estimates, especially when the analysis is extended into the highly nonlinear regime, with both the Hubble constant, $H_0$, and the clustering amplitude, $σ_8$, affected the most. Improvements in the modelling of nonlinear scales will therefore be needed if we are to resolve the current tension with more and better data. For a given prescription for the nonlinear power spectrum, using different corrections for baryon physics does not significantly impact the precision of Euclid, but neglecting these correction does lead to large biases in the cosmological parameters. In order to extract precise and unbiased constraints on cosmological parameters from Euclid cosmic shear data, it is therefore essential to improve the accuracy of the recipes that account for nonlinear structure formation, as well as the modelling of the impact of astrophysical processes that redistribute the baryons.

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arXiv2020

The ALPINE-ALMA [CII] survey: Dust attenuation properties and obscured star formation at z~4.4-5.8

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 158μm 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 ($β$), 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-$β$ 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-$β$ 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.

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arXiv2020

The ALPINE-ALMA [CII] Survey: The nature, luminosity function and star formation history of dusty galaxies up to z~6

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.

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