Related papers: Molecules in a gravitational collapse
The contraction processes of metal-free molecular clouds of starlike mass (or cloud cores) are investigated. We calculate radiative transfer of the H_2 lines and examine quasi-static contraction with radiative cooling. Comparing two…
We have studied the chemistry of nitrogen--bearing species during the initial stages of protostellar collapse, with a view to explaining the observed longevity of N2H+ and NH3 and the high levels of deuteration of these species. We followed…
We find that at redshifts z > 10, HD line cooling allows strongly-shocked primordial gas to cool to the temperature of the cosmic microwave background (CMB). This temperature is the minimum value attainable via radiative cooling. Provided…
We have included the chemical rate network responsible for the formation of molecular Hydrogen in the N-body hydrodynamic code, Hydra, in order to study the formation of the first cosmological at redshifts between 10 and 50. We have tested…
We discuss recent models of chemical evolution in the developing and collapsing protostellar envelopes associated with low-mass star formation. In particular, the effects of depletion of gas-phase molecules onto grain surfaces is…
We present some important conclusions from recent calculations pertaining to the collapse of rotating molecular cloud cores with axial symmetry, corresponding to evolution of young stellar objects through classes 0 and begin of class I.…
Galaxy formation depends on a complex interplay between gravitational collapse, gas accretion, merging, and feedback processes. Yet, after many decades of investigation, these concepts are poorly understood. This paper presents the argument…
On galactic scales, the surface density of star formation appears to be well correlated with the surface density of molecular gas. This has lead many authors to suggest that there exists a causal relationship between the chemical state of…
The chemistry of the early Universe is a fascinating field of study. Even in the absence of any elements heavier than lithium, a surprising degree of chemical complexity proves to be possible, giving the topic considerable interest in its…
We investigate the early formation of bound objects with masses comparable to the cosmological Jeans mass (10^5 solar masses). We follow the growth of isolated spherically symmetric density peaks starting from the linear perturbative…
A broad fundamental understanding of the mechanisms underlying the phenomenology of supercooled liquids has remained elusive, despite decades of intense exploration. When supercooled beneath its characteristic melting temperature, a liquid…
We report new calculations of the cooling rate of primordial gas by the HD molecule, taking into account its ro-vibrational structure. The HD cooling function is calculated including radiative and collisional transitions for J\le8…
Within the precise cosmological framework provided by the Lambda-Cold Dark Matter model and standard Big Bang nucleosynthesis, the chemical evolution of the pregalactic gas can now be followed with accuracy limited only by the uncertainties…
The preheating of intergalactic medium(IGM) by structure collapsing and ultraviolet background(UVB) are investigated in cosmological hydrodynamical simulations. When gravitational collapsing is the sole heating mechanism, we find that (1)…
The formation of molecular clouds out of HI gas is the first step toward star formation. Its metallicity dependence plays a key role to determine star formation through the cosmic history. Previous theoretical studies with detailed chemical…
The detection of $\rm z>6$ quasars reveals the existence of supermassive black holes of a few $\rm 10^9~M_{\odot}$. One of the potential pathways to explain their formation in the infant universe is the so-called direct collapse model which…
We present hydrostatic equilibrium models of spherical, self-gravitating clouds of helium and molecular hydrogen, focusing on the cold, high-density regime where solid- or liquid-hydrogen can form. The resulting structures have masses from…
Thermal and chemical evolution of primordial gas clouds irradiated with far-ultraviolet (FUV; < 13.6 eV) radiation is investigated. In clouds irradiated by intense FUV radiation, sufficient hydrogen molecules to be important for cooling are…
We discuss a possible delay experienced by protogalaxies with low column density of gas in forming stars over large scales. After the hydrogen has recombined, as the external ionizing UV flux decreases and the metal abundance $Z$ increases,…
Different from Milky-Way-like galaxies, discs of gas-rich galaxies are clumpy. It is believed that the clumps form because of gravitational instability. However, a necessary condition for gravitational instability to develop is that the…