Related papers: Astronomy: Trouble at first light
The evolution of the number density of galaxies in the universe, and thus also the total number of galaxies, is a fundamental question with implications for a host of astrophysical problems including galaxy evolution and cosmology. However…
Star formation remains an unsolved problem in astrophysics. Numerical studies of large-scale structure simulations cannot resolve the whole process and their approach usually assumes that only gas denser than a typical threshold can host…
Most stars - especially young stars - are observed to be in multiple systems. Dynamical evolution is unable to pair stars efficiently, which leads to the conclusion that star-forming cores must usually fragment into \geq 2 stars. However,…
The first 900 million years (Myr) to redshift z~6 (the first seven per cent of the age of the Universe) remains largely unexplored for the formation of galaxies. Large samples of galaxies have been found at z~6, but detections at earlier…
This article summarizes the possible roles of neutrinos in cosmology, from the first three minutes onward. The fact that primordial neutrinos are about as numerous as the photons of the cosmological background radiation means that neutrino…
Our standard model of the Universe predicts the distribution of dark matter to $1\%$ at the scales needed for upcoming experiments, yet our predictions for how the luminous matter -- which has interactions besides gravity -- is distributed…
Although fundamental for astrophysics, the processes that produce massive stars are not well understood. Large distances, high extinction, and short timescales of critical evolutionary phases make observations of these processes…
I describe the current state of our knowledge of the mapping between the initial masses of stars and the compact objects -- particularly neutron stars and black holes -- that they produce. Most of that knowledge is theoretical in nature,…
The emergence of the first black holes during the first billion years of cosmic history marks a key event in cosmology. Their formation is part of the overall process of ending the cosmic dark ages, when the first stars appeared in low-mass…
We find constraints on minimum and maximum mass of ordinary neutron stars imposed by their early evolution (protoneutron star stage). We calculate models of protoneutron stars using a realistic standard equation of state of hot, dense…
The standard theory of cosmic structure formation posits that the present-day rich structure of the Universe developed through gravitational amplification of tiny matter density fluctuations generated in its very early history. Recent…
In the first two years of operation JWST has delivered key new insights into the formation and evolution of galaxies in the early Universe. By combining imaging with spectroscopy, we discovered and characterised the first generation of…
The stellar initial mass function (IMF) describes how many stars form at which mass. Despite recent observational progress, many fundamental properties of the IMF are still unknown. Specifically the question, whether starbursts are biased…
The first stars ended the cosmic Dark Ages and created the first heavy elements necessary for the formation of planets and life. The properties of these stars remain uncertain, and it may be decades before individual Pop III stars are…
Most of the mass density in the Universe---and in the halo of our own galaxy---exists in the form of dark matter. Overall, the contribution of luminous matter (in stars) to the mass density of the Universe is less than 1\%; primordial…
Observations in the optical, in X-rays, and gravitational lensing of galaxies, clusters of galaxies, and large-scale structure are beginning to provide clues to the dark matter problem. I review the impact of these observations on some of…
A remarkable span of frontier astrophysics, from gravitational-wave archaeology to the origin of the elements to interpreting snapshots of the earliest galaxies, depends sensitively on our understanding of massive star formation and…
The study of the formation of massive stars presents complex challenges from both theoretical and observational points of view. The initial phases of evolution, for instance, remain almost hidden except at radio and IR wavelengths. In this…
Using our recently improved understanding of star cluster physics, we are now within reach of answering a number of fundamental questions in contemporary astrophysics. Star cluster physics has immediate bearing on questions ranging from the…
Mass is constantly being recycled in the universe. One of the most powerful recycling paths is via stellar mass-loss. All stars exhibit mass loss with rates ranging from ~10(-14) to 10(-4) M(sun) yr-1, depending on spectral type, luminosity…