Related papers: High Redshift Quasars and Star Formation History
Observed magnitudes of many quasars with redshifts exceeding $z=5$ correspond to luminosities $L_{\rm bol} > 10^{14}\,L_\odot$. The standard mechanism of quasar energy release by accretion suggests that masses of superluminous quasars…
Cosmic objects with magnetic fields (quasars, radiogalaxies) are observed at redshifts $z\geq 7$ (Wang et al., 2021, Fan et al., 2023, Yang et al., 2024) and more (for instance, for $z = 10.073\pm 0.002$, Goulding et al., 2023) indicates…
Several arguments suggest that quasars at z > 4 may be in the cores of future giant ellipticals, and forming at the very highest peaks of the primordial density field. A strong bias-driven primordial clustering is then expected in these…
We study the observational signatures of a potential population of low-luminosity quasars at high redshifts in a LambdaCDM cosmology. We derive the evolution of the quasar luminosity function at fainter luminosities and higher redshifts…
Quasars are powerful systems whose spectrum is rich of metal features that allow us to investigate the chemical evolution of galaxies at very high redshift, even close to the reionization epoch. I review the main observational constraints…
The discovery of luminous quasars at redshifts up to 7.5 demonstrates the existence of several billion M_sun supermassive black holes (SMBHs) less than a billion years after the Big Bang. They are accompanied by intense star formation in…
The first stars are believed to have formed a few hundred million years after the big bang in so-called dark matter minihalos with masses ~10^6 M_sun. Their radiation lit up the Universe for the first time, and the supernova explosions that…
Quasars at z>4 provide direct information on the first massive structures to form in the Universe. Recent ground-based optical surveys (e.g., the Sloan Digital Sky Survey) have discovered large numbers of high-redshift quasars, increasing…
We present observations of 11 high redshift quasars ($3.9 \la z \la 5.0$) observed with low spectral resolution in the restframe ultraviolet using FORS 1 at the VLT UT 1. The emission-line fluxes of strong permitted and intercombination…
We outline a method to infer the global history of star formation in galaxies with input only from absorption-line observations of quasars. The application of the method to existing data leads to the conclusion that most stars formed at…
Surveys of redshifted emission lines in the near-infrared will provide unique information on the cosmic star formation history. Near-infrared Halpha surveys will probe the cosmic star formation density and the evolution of the luminosity…
Analysis of the deepest available images of the sky, obtained by the Hubble Space Telescope, reveals a large number of candidate high-redshift galaxies. A catalogue of 1,683 objects is presented, with estimated redshifts ranging from $z=0$…
Star forming galaxies represent a valuable tracer of cosmic history. Recent observational progress with Hubble Space Telescope has led to the discovery and study of the earliest-known galaxies corresponding to a period when the Universe was…
The recent discoveries of luminous quasars at high redshifts imply that black holes more massive than a few billion solar masses have been assembled already when the universe was less than a billion years old. We show that the existence of…
The redshift where the first stars formed is an important and unknown milestone in cosmological structure formation. The evidence linking gamma ray bursts (GRBs) with star formation activity implies that the first GRBs occurred shortly…
It is currently unknown whether the Universe was reionized by quasars or stars at z>5. We point out that quasars can be best distinguished from stellar systems by their X-ray emission. Based on a simple hierarchical CDM model, we predict…
Interstellar dust plays a crucial role in the evolution of the Universe by assisting the formation of molecules, by triggering the formation of the first low-mass stars, and by absorbing stellar ultraviolet-optical light and subsequently…
The formation of the first generations of stars at redshifts z > 15-20 signaled the transition from the simple initial state of the universe to one of increasing complexity. We here review recent progress in understanding the assembly…
When did galaxies start forming stars? What is the role of distant galaxies in galaxy formation models and the epoch of reionization? What are the conditions in typical star-forming galaxies at redshifts >~4? Why is galaxy evolution…
Observations of CO molecules in the millimetrer domain at high redshift (larger than 1), have provided interesting informations about star formation efficiency, and its evolution with redshift. Due to the difficulty of the detections,…