The nature of the first galaxies that reionised the universe during the Epoch of Reionisation (EoR) remains unclear. Attempts to directly determine spectral properties of these early galaxies are affected by both limited photometric constraints across the spectrum and by the opacity of the intergalactic medium to the Lyman Continuum (LyC) at high redshift. We approach this by analysing properties of analogous extreme emission line galaxies (EELGs, [OIII]+Hbeta EW $\gt 400$) at $2.5\lt z\lt 4$ from the ZFOURGE survey using the Multi-wavelength Analysis of Galaxy Physical Properties (MAGPHYS) SED fitting code. We compare these to galaxies at $z \gt 5.5$ observed with the James Webb Space Telesope with self-consistent spectral energy distribution fitting methodology. This work focuses on the comparison of their UV slopes (${\unicode{x03B2}}_P$), ionising photon production efficiencies $\xi_{ion}$, star formation rates and dust properties to determine the effectiveness of this analogue selection technique. We report the median ionising photon production efficiencies as log$_{10}(\xi_{ion}/(Hz\ {\rm erg}^{-1}))=$$25.14^{+0.06}_{-0.04}$, $25.16^{+0.06}_{-0.05}$, $25.16^{+0.04}_{-0.05}$, $25.18^{+0.06}_{-0.07}$ for our ZFOURGE control, ZFOURGE EELG, JADES, and CEERS samples, respectively. ZFOURGE EELGs are 0.57 dex lower in stellar mass and have half the dust extinction, compared to their ZFOURGE control counterparts. They also have a similar specific star formation rates and ${\unicode{x03B2}}_P$ to the $z\gt 5.5$ samples. We find that EELGs at low redshift ($2.5\lt z\lt 4$) are analogous to EoR galaxies in their dust attenuation and specific star formation rates. Their extensive photometric coverage and the accessibility of their LyC region opens pathways to infer stellar population properties in the EoR.

The measurement of Hα luminosity for large numbers of galaxies is important to investigate recent star formation history of galaxies. With SED fitting that includes emission line templates, we extract individual galaxy Hα luminosities from broad-band photometry. We compare Hα luminosity function with the result of a narrow-band survey, HiZELS, and find there are more luminous galaxies in Hα than previously reported. As a result, our derived star formation rate density at z ∼ 2.3 turns out to be 2.2 times higher than previous studies. Most of the offset in the results can be explained by missing Hα in the HiZELS photometric aperture and different methods for dust extinction correction.

We present 0.″2–0.″4 resolution ALMA images of the submillimeter dust continuum and the CO, H2O, and H2O+ line emission in a z = 3.63 strongly lensed dusty starburst. We construct the lens model for the system with an MCMC technique. While the average magnification for the dust continuum is about 11, the magnification of the line emission varies from 5 to 22 across the source, resolving the source down to sub-kpc scales. The ISM content reveals that it is a pre-coalescence major merger of two ultra-luminous infrared galaxies, both with a large amount of molecular gas reservoir. The approaching galaxy in the south shows no apparent kinematic structure with a half-light radius of 0.4 kpc, while the preceding one resembles a 1.2 kpc rotating disk, separated by a projected distance of 1.3 kpc. The distribution of dust and gas emission suggests a large amount of cold ISM concentrated in the interacting region.

A large-scale structure has been recently discovered at z = 1.7, around a powerful FRII radio galaxy. Eight Star Forming Galaxies (SFGs) have been discovered within Δ z ≍ 0.0095 and at < 1 Mpc from the FRII, indicating that this is a signpost of a protocluster. Furthermore, a significant X-ray diffuse emission overlapping the Eastern lobe of the FRII has been detected. Protoclusters are the ideal targets to investigate the complex assembly processes leading to the formation of local galaxy clusters. We will exploit new ALMA CO(2-1) observations (PI: R. Gilli) of the entire region around the FRII galaxy to trace the molecular gas content, in order to discover new protocluster members. Coupling these measurements with the multi-wavelength data coverage available for this field, we aim at placing constrains on the physical conditions in which star formation occurs, and ultimately infer the role of the radio jets in triggering it.

We have conducted a multi-wavelength survey of distant (1.3 < z < 2.6) luminous quasars host galaxies using the Keck integral field spectrograph (IFS) OSIRIS and laser guide star adaptive optics (LGS-AO) system, ALMA, HST and VLA. Studying distant quasar host galaxies is essential for understanding the role of active galactic nuclei (AGN) feedback on the interstellar medium (ISM), and its capability of regulating the growth of massive galaxies and their supermassive black holes (SMBH). The combination of LGS-AO and OSIRIS affords the necessary spatial resolution and contrast to disentangle the bright quasar emission from that of its faint host galaxy. We resolve the nebular emission lines, [OIII], [NII],, and [SII] at a sub-kiloparsec resolution to study the distribution, kinematics, and dynamics of the warm-ionized ISM in each quasar host galaxy. The goal of the survey was to search for ionized outflows and relate their spatial extent and energetics to the star-forming properties of the host galaxy. Combining ALMA and OSIRIS, we directly test whether outflows detected with OSIRIS are affecting the molecular ISM. We find that several mechanisms are responsible for driving the outflows within our systems, including radiation pressure in low and high column density environments as well as adiabatic and isothermal shocks driven by the quasar. From line ratio diagnostics, we obtain resolved measurements of the photoionization mechanisms and the gas-phase metallicity. We find that the quasars are responsible for photoionizing the majority of the ISM with metalicities lower than that of gas photoionized by AGN in the low redshift systems. We are now obtaining detailed observations of the circumgalactic medium (CGM) of these systems with the Keck Cosmic Web Imager (KCWI). The gas in the CGM may play an essential role in the evolution of these galaxies.

We compiled a sample of 57 galaxies with spectroscopically confirmed redshifts and SPIRE detections in all three bands at z = 2.5-6.4, and compared their SPIRE colors with SED templates from local and high-z libraries. We find that local calibrations are inconsistent with high-z observations. For high-z libraries, the templates with an evolution from z = 0 to 3 can describe the average colors of the observations at high redshift well. Based on the templates, we defined color cuts to divide the SPIRE color-color diagram into different regions with different mean redshifts. We tested this method and two other color cut methods using a larger sample (783 galaxies) with photometric redshifts. We find that these color cuts can separate the sample into subsamples with different mean redshifts, but the dispersion of redshifts in each subsample is considerably large. Additional information is needed for better sampling.

Quasars are tracers of the cosmological evolution of the Black Hole mass – host galaxy relation, and indicate that the formation of BH anticipated that of the host galaxies. We find that selection effects and statistical biases dominate the interpretation of the observational results; and co-evolution (= constant BH/galaxy mass ratio) is still compatible with observations.

We use the full SED of a well observed dwarf galaxy, I Zw 18, to evaluate what inferences can be made about very high-redshift galaxies from their UV SED's alone.

We summarise the current status of our project to identify and classify ~ 6-10 galaxies thanks to strong gravitational lensing. Building on the detailed work by Richard et al. (2006), we present results from new follow-up observations undertaken with the ACS/HST and the Spitzer space telescope and compare our results with findings from the Hubble Ultra-Deep Field (UDF).

This paper reviews the star formation history of the Universe, from the first stars to the current day, with emphasis on the critical analysis of the techniques that have been used to determine it, especially considering the role of dust. We consider the first population of stars, the Population III stars, were formed at redshifts ranging as high as z ~ 60, the formation of the Globular Clusters, the main epoch of galaxy formation. In the sub-mm galaxies and high-redshift radio galaxies the collapse of massive galaxies was surprisingly rapid, and that the growth of super-massive black holes at their centers provides the energy input to eject the galactic interstellar medium while at the same time precipitating a final burst of star formation and the ejection of their ISM so that the subsequent evolution of these galaxies is passive.

The stellar mass-metallicity relations of star-forming galaxies at intermediate-z (0.4<z<1) and high-z (z≥2) are compared with the local SDSS galaxies. It shows obvious evolutionary effect, i.e., at a given stellar mass, the intermediate-z galaxies show about 0.3 dex lower metallicity, and the high-z galaxies show about 0.56 dex more metal-deficient than the local ones. These distant galaxies will produce these important parts of their metals during the consequent evolutionary process. A close-box model can explain this evolutionary process generally.

We present the results of a comprehensive Spitzer survey of 70 radio galaxies across 1 < z < 5.2. Using IRAC (3.6–8.0μm), IRS (16 μm) and MIPS (24–160 μm) imaging, we decompose the rest-frame optical to infrared spectral energy distributions into stellar, AGN, and dust components and determine the contribution of host galaxy stellar emission at rest-frame 1.6 μm (H-band). We find that the fraction of emitted light at rest-frame 1.6 μm from stars is >80% for over half the high redshift radio galaxies. The other radio galaxies have 1.6 μm stellar fractions spanning the range 20–80%. The resultant stellar luminosities imply stellar masses of 1011−12M⊙, independent of redshift, indicating that radio galaxies are amoungst the most massive galaxies observed over this redshift range. Powerful radio galaxies tend to lie in a similar region of mid-IR color-color space as unobscured AGN, despite the inferred stellar contribution to their shorter-wavelength, mid-IR SEDs. The stellar fraction of the rest-frame 1.6 μm luminosity has no correlation with redshift, radio luminosity, or rest-frame mid-IR (5 μm) luminosity. The bolometric energy output of these sources is dominated by the infrared, and the mid-IR luminosities are found to be similar to that of lower redshift (z < 1) radio galaxies. As expected, these exceptionally high mid-IR luminosities are consistent with an obscured, highly-accreting AGN. A weak, but significant, correlation of stellar mass with radio luminosity is found, consistent with earlier results.

We present GALEV evolutionary synthesis models for Simple Stellar Populations (SSPs = single burst, single metallicity) like star clusters or galaxy pixels and for galaxies of various types on the basis of their respective typical star formation histories, ranging from exponentially declining on a timescale of 1Gyr for the classical elliptical model through constant for Sd galaxies, and also allowing for starbursts of various strengths occurring at various evolutionary stages. Models yield the time evolution of the stellar population in terms of color-magnitude diagrams CMDs ($U$\dots $K$), spectra (90Å…160$\mu$m) including gaseous emission in terms of lines and continuum, luminosities, colors and M/L-ratios in various filter systems (e.g. Johnson $U$\dots $K$, HST, Washington, Strömgren), and Lick indices (http://www.astro.physik.uni-goettingen.de/~galev). For galaxies, the redshift evolution is obtained from the time-evolving spectra assuming a standard cosmology (H$_0=65, \Omega_0=0.3, \Omega_{\Lambda}=0.7$) and consistently accounting for evolutionary and cosmological corrections as well as for the attenuation of light from distant galaxies by intervening HI.

I summarise the ELT requirements derived from the science cases in the area of galaxy formation/evolution and cosmology. This summary is based on the talks, posters and discussion in parallel Session A of this meeting, but also makes use of various publically-available ELT science case documents. Topics covered include studies of black holes, dark matter, properties of galaxies at a range of redshifts (including the first galaxies to form), fundamental constants and cosmology.

We compare the properties of dwarf galaxies in the Local Group with the simulated galaxies formed before reionization in a cosmological simulation of unprecedented spatial and mass resolution including radiative feedback effects. We find that a subset of the Local Group dwarfs, the dwarf Spheroidals, are remarkably similar to the simulated dwarf galaxies in all their properties already before reionization. Simulated and observed dwarf Spheroidal galaxies not only have similar properties but also follow the same scaling relations. Based on this similarity and on the observed ages of their dominant stellar populations we propose the hypothesis that Local Group dwarfs form in two different ways: (i) most dwarf Spheroidals are pristine fossils of the pre-reionization era and (ii) dwarf irregulars are more massive galaxies that formed most of their stars later, after reionization. There is also a group of “polluted fossils” with properties that are intermediate between these two main groups. We predict the existence of many more dwarf Spheroidals, fainter and with lower surface brightness than the observed population.