Related papers: The Dark Universe: The First Molecules
In the Big Bang scenario, the early Universe is characterized by the {\it particle era}, i.e. a Universe made of particles. This period connects both scales of fundamental physics: infinitesimally small and infinitely large. So, particle…
In popular cold dark matter cosmological scenarios, stars may have first appeared in significant numbers around a redshift of 10 or so, as the gas within protogalactic halos with virial temperatures in excess of 20,000 K (corresponding to…
We discuss the heat history of the early Universe and its further evolution in the framework of modern cosmological models of general relativity (GR) and alternative theories of gravity. Of great importance are the new puzzling forms of…
We study particle decay as the origin of dark radiation. After elaborating general properties and useful parametrisations we provide model-independent and easy-to-use constraints from nucleosynthesis, the cosmic microwave background and…
We study the formation of first molecules, negative Hydrogen ions and molecular ions in model of the Universe with cosmological constant and cold dark matter. The cosmological recombination is described in the framework of modified model of…
Evidence has continued to accumulate over the last few decades as to the existence and nature of dark matter. Depending on the particle candidate, the dark matter can exhibit one of several cosmologically defined models: hot dark matter,…
The standard model for the formation of structure assumes that there existed small fluctuations in the early universe that grew due to gravitational instability. The origins of these fluctuations are as yet unclear. In this work we propose…
A new mechanism describing the formation of protogalaxies is proposed, which is based on the second- order phase transition in the inflation stage and the domain wall formation upon the end of inflation. The presence of closed domain walls…
Primordial chemistry began in the recombination epoch when the adiabatic expansion caused the temperature of the radiation to fall below 4000 K. The chemistry of the early Universe involves the elements hydrogen, its isotope deuterium,…
We explore some basic observational consequences of assuming that the dark matter in the Milky Way consists mainly of molecular clouds, and that cosmic rays can penetrate these clouds. In a favoured model of the clouds, this penetration…
The evolution of the Universe between inflation and the onset of big bang nucleosynthesis is difficult to probe and largely unconstrained. This ignorance profoundly limits our understanding of dark matter: we cannot calculate its thermal…
The Cosmic Dark Ages represent the period in the early evolution of the Universe, starting immediately after the decoupling of CMB photons from matter, and ending with the formation of the first stars and galaxies. The HI signal from the…
Dark matter(DM) is the only possible candidate which would be apart from the thermal equilibrium before Big Bang nucleosynthesis(BBN) in accordance with current DM searches. In this work, we report a generic scenario that primordial…
Mirror matter is a stable self-collisional dark matter candidate. If parity is a conserved unbroken symmetry of nature, there could exist a parallel hidden (mirror) sector of the Universe composed of particles with the same masses and…
We discuss the possibility of forming primordial black holes during a first-order phase transition in the early Universe. As is well known, such a phase transition proceeds through the formation of true-vacuum bubbles in a Universe that is…
About 40 years ago, the neutrino was ruled out as the dark matter particle based on several arguments. Here I use the well-established concept of quantum uncertainties of position and momentum to describe the decoupling of neutrinos from…
In this article we extend the study performed in our previous article on the collapse of primordial objects. We here analyze the behavior of the physical parameters for clouds ranging from $10^7M_\odot$ to $10^{15}M_\odot$. We studied the…
In the early Universe, dark energy may have a non-negligible contribution. If this dark energy corresponds to an early cosmological constant, it leads to a late-time huge dark energy density which is much larger than what is expected for…
Regarding long life particles produced during preheating after inflation as dark matter, we find that its back reaction on the field $\phi$ could lock $\phi$ in a false vacuum up to today. This false vacuum can drive the accelerated…
Recent observations of hydrogen absorption that occurred when the first stars turned on may give insights into the nature of dark matter.