<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Statistical properties of dark matter mini-haloes and\r\nthe criterion for HD formation in the early universe"^^ . "The aim of this work is to explore how dark matter structures and astronomical objects\r\n(the first generation of stars) formed in the high-redshift universe. We investigate\r\nproperties of dark matter mini-haloes and clarify the process of primordial star formation\r\nthat takes place in different dark matter mini-haloes. The specific questions that\r\nwe aim to answer in this work include how dark matter mini-haloes found at z >= 15\r\ndiffer from their more massive lower-redshift counterparts and what determines the\r\namount of HD that forms in primordial gas at the initial stage of protostellar collapse.\r\nWe ran a high-resolution N-body simulation that has the highest mass resolution ever\r\nachieved for a representative cosmological volume at these high redshifts, and made\r\nprecision measurements of various physical properties that characterise dark matter\r\nhaloes. As expected from the differences in the slope of the dark matter density\r\npower spectrum, the dependence of formation time on dark matter halo mass is very\r\nweak in the case of the haloes that we study here. Despite this difference, dark matter\r\nstructures at high redshift share many properties with their much more massive\r\ncounterparts that form at later times. We ran a separate set of cosmological hydrodynamical\r\nsimulations to study gas starting to collapse in dark matter haloes. We found\r\nthat in some of our simulated mini-haloes, HD cooling became important during the\r\ninitial collapse, and investigated in detail why this occurred. We compared HD-rich\r\nand HD-poor mini-haloes in our simulations and found that the amount of HD that\r\nforms is linked to the speed of the gravitational collapse. If the collapse is rapid,\r\ndynamical heating prevents the gas from cooling to temperatures low enough for HD\r\ncooling to become important, but if the collapse is slow, HD cooling can come to\r\ndominate, resulting in a minimum gas temperature which is lower by a factor of two.\r\nWe investigated what properties of the mini-haloes were responsible for determining\r\nthe collapse time, and showed that, contrary to previous suggestions, the mass of the\r\nmini-halo and the rotational energy of the gas appear to have little in\r\nuence on the\r\nspeed of the collapse. We therefore suspect that the main factor determining whether\r\nthe collapse is slow or rapid, and hence whether HD cooling becomes important or\r\nnot, is the degree of turbulence in the gas."^^ . "2015" . . . . . . . "Mei"^^ . "Sasaki"^^ . "Mei Sasaki"^^ . . . . . . "Statistical properties of dark matter mini-haloes and\r\nthe criterion for HD formation in the early universe (PDF)"^^ . . . "thesis_0812_final2.pdf"^^ . . . "Statistical properties of dark matter mini-haloes and\r\nthe criterion for HD formation in the early universe (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Statistical properties of dark matter mini-haloes and\r\nthe criterion for HD formation in the early universe (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Statistical properties of dark matter mini-haloes and\r\nthe criterion for HD formation in the early universe (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Statistical properties of dark matter mini-haloes and\r\nthe criterion for HD formation in the early universe (Other)"^^ . . . . . . "small.jpg"^^ . . . "Statistical properties of dark matter mini-haloes and\r\nthe criterion for HD formation in the early universe (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #18293 \n\nStatistical properties of dark matter mini-haloes and \nthe criterion for HD formation in the early universe\n\n" . "text/html" . . . "520 Astronomie"@de . "520 Astronomy and allied sciences"@en . .