Related papers: Early formed astrophysical objects and cosmologica…
In these lectures I review observations of star-forming molecular clouds in our Galaxy and nearby galaxies to develop a physical intuition for understanding star formation in the local and high-redshift Universe. A lot of this material is…
Any realistic theory of galaxy formation must be set in the context of a model for the formation of structure in the universe. We describe a powerful approach -- semi-analytic modelling -- that combines a set of simple rules describing the…
Observations of intensely bright star-forming galaxies both close by and in the distant Universe at first glance seem to emphasize their similarity. But look a little closer, and differences emerge.
The most massive galaxies in the present-day Universe are found to lie in the centres of rich clusters. They have old, coeval stellar populations suggesting that the bulk of their stars must have formed at early epochs in spectacular…
Recent spacecraft observations exploring solar system properties impact standard paradigms of the formation of stars, planets and comets. We stress the unexpected cloud of microscopic dust resulting from the DEEP IMPACT mission, and the…
The history of the transition from a neutral intergalactic medium (IGM) to one that is almost fully ionized can reveal the character of cosmological ionizing sources and set important constraints on the stellar birthrate at high redshifts.…
Quantum fluctuations of a complex, baryonic charged scalar field caused by inflation can generate large domains, which convert later into antimatter regions. As a result the Universe can become globally matter-dominated, with minor…
(Abridged) Fundamental tensions between observations and dark-matter based cosmological models have emerged. This updated review has two purposes: to explore new tensions that have arisen in recent years, compounding the unresolved tensions…
In typical astrophysical environments, the abundance of heavy elements ranges from 0.001 to 2 times the solar concentration. Lower abundances have been seen in select stars in the Milky Way's halo and in two quasar absorption systems at…
The present work is connected with the investigation of the origin and properties of compact astrophysical objects endowed with strangeness, with the objective of finding out their relevance in the formation and evolution of the universe.…
The astronomical dark matter is an essential component of the Universe and yet its nature is still unresolved. It could be made of neutral and massive elementary particles which are their own antimatter partners. These dark matter species…
The initial conditions of our Universe can be summarized on a single sheet of paper. Yet the Universe is full of complex structures today, such as stars, galaxies and groups of galaxies. In this review I describe the standard theoretical…
A specific class of flat Emergent Universe (EU) is considered and its viability is tested in view of the recent observations. Model parameters are constrained from Stern data for Hubble Parameter and Redshift ($H(z)$ vs. $z$) and from a…
There is accumulating observational evidence suggesting that damped Ly$\alpha$ absorption systems systems are the progenitors of present-day spiral galaxies. We use the observed properties of these systems to place constraints on the…
James Webb Space Telescope's (JWST) observations since its launch have shown us that there could be very massive and very large galaxies, as well as massive quasars very early in the history of the universe, conflicting expectations of the…
The comparison of cosmic abundances of the light elements with the density of baryonic stars and gas in the universe today provides a critical test of big bang theory and a powerful probe of the nature of dark matter. A new technique allows…
Topological defects are common in many everyday systems. In general, they appear if a symmetry is broken at a rapid phase transition. In this article, I explain why it is believed that they should have also been formed in the early universe…
The presence of massive galaxies at high $z$ as recently observed by JWST appears to contradict the current $\Lambda$CDM cosmology. Here we aim to alleviate this tension by incorporating uncertainties from three sources in counting…
In this work, we outline a new general relativistic cosmology. In this cosmology, the universe originates in the infinite past from sparsely distributed neutral matter and ends in the infinite future as a hot, relativistic plasma. The…
The nature of dark matter remains a central problem in cosmology. A compelling possibility is that dark matter is macroscopic, consisting of composite objects formed in the early Universe. We introduce the QCD-AQN framework, a…