Instruments like HARMONI on the ELT will likely be able to observe the first spatially resolved spectra of the very earliest (z~10) galaxies. Contained within these spectra will be details of the very first and as of yet unobserved stars, i.e. Population III stars. Detecting the emission from Pop. III stars would provide significant insight into star formation, galaxy formation and evolution...
We will review Euclid satellite, in particular details of the planned wide and deep surveys. The wealth of expected data is enormous and it will constitute a fantastic database for observations on large telescopes.
Within standard $\Lambda$CDM cosmology, Population III (Pop III) star formation in minihalos of mass $M_\mathrm{halo}> 5\times10^5$ M$_\odot$ provides the first stellar sources of Lyman$\alpha$ (Ly$\alpha$) photons. The Experiment to Detect the Global Epoch of Reionization Signature (EDGES) has measured a strong absorption signal of the redshifted 21 cm radiation from neutral hydrogen at...
Unveiling the active early galaxy assembly with emission-lines and ELTs
Passive galaxies in the early Universe: results and challenges
We search the five CANDELS fields for passively evolving a.k.a. ``red and dead'' massive galaxies in the first 2 Gyr after the Big Bang. By means of top-hat star-formation histories, to model an early and abrupt quenching of the activity, we fit the observed photometric data using a demanding probabilistic approach to single out only very reliable passive candidates. Using libraries of models...
In the Lambda CDM scenario, the smallest dark matter haloes are the first to collapse, and therefore we expect dwarf galaxies to be the sites of the earliest star formation activity in the Universe. Resolved stellar population studies of nearby dwarf galaxies are extremely valuable for probing the early Universe, since they allow us to reconstruct the dwarfs' star formation histories with...
While traditionally associated with AGN, the properties of the rest-frame UV CIII] and CIV emission lines are still uncertain as large, unbiased samples of sources are scarce. Recently, CIII] and CIV emission lines have been observed in galaxies in the early Universe ($z>5$) and have been proposed as the prime way of measuring their redshift and studying their stellar populations. I will...
The early growth of the first supermassive black holes
Results from numerical simulations including non-equilibrium chemistry, stellar evolution, metal spreading and raditive transfer will be discussed in order to shed light on the primordial cosmological epochs. Simulation results will be compared against observational data and employed to study the formation of the first galaxies, investigate their impact on high-z dumped Lyalpha gas and GRB...
The identification of young massive star clusters (YMCs) at cosmological distance
is becoming a real fact. The occurrence of such systems is believed to increase at
high redshift, eventually enclosing a significant fraction of the star formation activity
of the Universe, in an epoch when also globular clusters (GC) formed. The potential role
of such stellar systems play during reionization,...
Strong gravitational lensing by galaxy clusters can magnify the light
of background sources by factors of tens or more, pushing the current
observational limits towards the faint and distant Universe.
Thanks to coordinated programs using deep HST imaging (from large
programmes such as CLASH, Hubble Frontier Fields and RELICS) and
spectroscopy from MUSE in cluster fields, we can now...
The detection and characterization of early reionized regions will be a key topic for future Extremely Large Telescopes. In this talk I will present the first confirmation of a reionized overdensity at z~7 in the BDF field, based on a combination of deep HST and VLT multi-band imaging and VLT-FORS2 spectroscopy. The BDF field hosts a factor of ~3-4 overdensity of faint LBGs and three confirmed...
Reionisation was a process that lasted for most of the early history of the Universe and up to a redshift of 6. We propose to follow that history from redshift 15 to redshift 6. For that we should need a set of narrow band filters, spanning Ly_alpha from z~6 to z~14.
We will perform imaging through those narrow band filters searching for Ly_alpha emitters at different redshifts. We are aware...
We report the discovery of 10-kpc scale [CII] 158um halos surrounding star-forming galaxies in the early Universe. We choose deep ALMA data of 18 galaxies each with a star-formation rate of ~ 10-70 Msun with no signature of AGN whose [CII] lines are individually detected at z=5.153-7.142, and conduct stacking of the [CII] lines and dust-continuum in the uv-visibility plane. The radial profiles...
In our current understanding of the reionization era, the sources responsible for the transition of the universe from a neutral Hydrogen state to an ionized state are likely faint, low mass, star-forming galaxies. One way to study this type of population is to determine the Luminosity Function (LF) of galaxies selected from their Ly-a emission. However, the current studies and their...
The enterprise of finding, confirming and characterising z>7 galaxies in the era of Cosmic Reionisation has developed rapidly in recent years, due to the combined power of HST, Spitzer and ground based-telescopes. An important development has been the discovery and study of luminous 7<z<9 galaxies with a red [3.6]-[4.5] micron colour whose prominent Lyman-alpha emission might indicate they lie...
Distant luminous Lyman-alpha emitters are excellent targets for detailed observations of galaxies in the epoch of reionisation . Spatially resolved observations of these galaxies allow us to simultaneously probe the emission from young stars, partially ionised clouds in the interstellar medium and to constrain the properties of surrounding hydrogen gas in the circumgalactic medium. Hence,...
Determining the period when the first galaxies emerged from a dark intergalactic medium represents a fundamental milestone in assembling a coherent picture of cosmic history. But the so-called ‘Cosmic Dawn’ period is not accessible yet directly by current ground-based and space telescopes. But it can be constrained following two different methods : simulations of the first population of...
I will present an overview of recent results on analogs of the sources of cosmic reionization and very low (or zero) metallicity galaxies, whose detection and understanding are among the major goals with the next generation of facilities.
For example, I will discuss new insight on the far-UV SED and HeII emission from low metallicity galaxies, which is of importance for modeling and...
In this talk I shall use stellar population models to showcase analysis that could be performed with the E-ELT.
Dwarfs are the most common galaxies and play a significant role in galaxy evolution. However, they are objects still poorly understood. Although most of these systems present an old stellar population, disagreements remain about the period of their dominant star-formation activity.
Our objective is to investigate the dwarf galaxy population in building and acquiring samples of star-forming...
Astronomical observatories with large aperture telescopes, greater or equal to 20 meters in diameter, the so-called extremely large telescopes (ELTs), will provide high-quality data for applying spectral synthesis codes in order to accurately derive the star formation history (SFH) and Chemical Enrichment History (CEH) of galaxies. Therefore, extragalactic astronomy is on the verge of...
We present a detailed analysis of synthetic optical and UV emission lines of simulated galaxies out to the epoch of re-ionisation. The theoretical strong emission lines are derived from self-consistently coupling "new-generation" spectral models accounting for nebular emission from both young stars and AGN to new sets of high-resolved cosmological hydrodynamic zoom-in simulations of young...
Galaxy formation and evolution is critically regulated by
the flow of gas into and out of galaxies. While theoretical
models and cosmological simulations have extensively investigated
these phenomena and provided detailed predictions,
observations still lag behind due to observational difficulties
in detecting signatures of these processes, especially at
early cosmological epochs, when these...
I will present initial results from the VANDELS survey (DR2) quantifying the relationship between stellar mass and stellar metallicity for a sample of ~ 700 star-forming galaxies at 2.5 < z < 5.0. Stellar metallicities were determined for a set of high signal-to-noise ratio composite rest-UV spectra in bins of redshift and stellar mass (spanning the range 8.5 < log(M/Mo) < 10.2). We find...
The interstellar medium (ISM) of galaxies is composed of multiple components (molecular, neutral, ionized gas, and dust grains), which are related to each other through star formation — some are fuel for star formation (molecular gas) and some are the products of it (ionized gas, dust). Studying these different components simultaneously is crucial to fully understand the physics of star...
To obtain a reliable census of the star formation rate density of the universe, it is indispensable to measure the fraction of obscured star formation up to the epoch of reionization. One method to find distant starbursts - the so-called sub millimeter galaxies (SMGs) - is via strong lensing. I am presenting results from our on-going efforts via several (sub)mm facilities to reveal and...
GAs Stripping Phenomena in galaxies (GASP) is a program aimed at studying gas removal processes in nearby galaxies in different environments, using observations at different wavelengths (X, UV, optical, sub-mm, radio). The core of the program is an integral-field spectroscopic survey with MUSE at the VLT, that allows to study the spatially resolved properties of galaxies.
I will present some...
Dust production is a very important issue in galaxy evolution. Unfortunately, we are still unable to determine its formation mechanism. I will present the investigation of dust production in nine galaxies at redshift z > 6, for which dust emission has been detected. In recent years, more accurate measurements were made using the most powerful instruments, eg ALMA, which contributed to better...
The advent of the E-ELT telescope in the next decade, combined with the new generation instruments, will provide astronomers with the possibility to reach a spatial resolution higher than ever before (16 times the actual HST resolution), combined with a collecting area larger than 20 times the largest actual telescopes. This new facility will then offer the possibility to study the stellar...
Galaxy formation and evolution are driven by the (re)cycling of baryons in and out of galaxies. Active galactic nuclei and star formation can generate galaxy-scale outflows and fountains, which in part feed the extended interstellar and circum-galactic medium (ISM and CGM) reservoirs, and in part escape the galaxy halo hence enriching the intergalactic medium (IGM). In turn, cosmic inflows...
Quasars are known to be variable objects, which change their brightness in a wide range of time scales – from several hours to several years. In gravitational lens systems, we have an opportunity to observe the quasars intrinsic brightness variations repeated in all macroimages and shifted in time. One of the importance applications in astrophysics of measuring these time shifts is the study...
ALPINE is an ALMA large program designed to study gas and dust properties of a representative sample of more than one hundred main sequence star-forming galaxies with spectroscopic redshifts between 4 < z < 6, with SFR > ~10 M_Sun/yr and stellar mass ~9 < log(Mstar) < ~11.
I will present some results of the survey, focusing on:
- properties of the observed interstellar-medium (including...
Future JWST or any giant telescope imaging, intended to investigate the high-z Universe, are "contaminated" by a number of extended galaxies. They are either massive and/or low-z galaxies. Similarly, synoptic surveys like Euclid or LSST will commonly find such objects. We started their analysis with the study of the six most massive (>5x10^10 M_Sun) galaxies at z < 1 in the Hubble Ultra Deep...
Galaxy evolution science with ELTs in (and after) the era of JWST” (Mark Dickinson)
Studying single stars at cosmological distances is possible if the distant star is located near the caustic of a gravitational lens. This was proven possible recently with the observation of a star at redshift 1.49, Icarus, in Kelly et al. (2018) that was being lensed by the combination of a powerful lens (the galaxy clustr MACS1149) and a microlens inside the cluster. This type of alignments...
