<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "The Physical Properties and Cosmic Environments of Quasars in the First Gyr of the Universe"^^ . "Luminous quasars at redshift z >6, i.e. <1 Gyr after the Big Bang, are formidable probes of\r\nthe early universe, at the edge of the Epoch of Reionization. These sources are predicted\r\nto be found in high–density peaks of the dark matter distribution at that time, surrounded\r\nby overdensities of galaxies. In this thesis, we present a search for and study of the most\r\ndistant quasars, from the properties of their innermost regions, to those of their host galaxies\r\nand of their Mpc–scale environments. We search for the highest redshift quasars in the\r\nPanoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1, PS1), discovering\r\nsix new objects at z >6.5. Using optical/near–infrared spectroscopic data, we perform a homogeneous\r\nanalysis of the properties of 15 quasars at z> 6.5. In short : 1) The majority of z >6.5\r\nshow large blueshifts of the broad CIV 1549 Å emission line, suggesting the presence of strong\r\nwinds/outflows; 2) They already host supermassive black holes (M_BH = 0.3 - 5 x 10^9 M_sun) in their\r\ncenters, which are accreting at a rate comparable to a luminosity–matched sample at z =1-3)\r\nNo evolution of the Fe II/MgII abundance ratio with cosmic time is observed; 4) The sizes of\r\ntheir surrounding ionized bubbles weakly decrease with redshift. We present new millimeter\r\nobservations of the dust continuum and of the [CII] 158 mm emission line (one of the main\r\ncoolant of the intergalactic medium) in the host galaxies of four quasars, providing new accurate\r\nredshifts and [CII]/infrared luminosities. We study the Mpc–scale environment of a z =5.7\r\nquasar, via observations with broad– and narrow–band filters. We recover no overdensities\r\nof galaxies. Among the potential explanations for these findings, are that the ionizing radiation\r\nfrom the quasar prevents galaxy formation, the sources in the fields are dust–obscured,\r\nor quasars do not live in the most massive dark matter halos. Finally, we report sensitive\r\noptical/near–infrared follow–up observations of gas–rich companion galaxies to four quasars\r\nat z >6, firstly detected with the Atacama Large Millimeter Array (ALMA).With the exception\r\nof one source, we detect no emission from the stellar population of these galaxies. Our limits on\r\ntheir stellar masses (< 10^10 M_sun) and unobscured star formation rates ( . "2018" . . . . . . . "Chiara"^^ . "Mazzucchelli"^^ . "Chiara Mazzucchelli"^^ . . . . . . "The Physical Properties and Cosmic Environments of Quasars in the First Gyr of the Universe (PDF)"^^ . . . "thesis_phd_mazzucchelli_v2.pdf"^^ . . . "The Physical Properties and Cosmic Environments of Quasars in the First Gyr of the Universe (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "The Physical Properties and Cosmic Environments of Quasars in the First Gyr of the Universe (Other)"^^ . . . . . . "preview.jpg"^^ . . . "The Physical Properties and Cosmic Environments of Quasars in the First Gyr of the Universe (Other)"^^ . . . . . . "medium.jpg"^^ . . . "The Physical Properties and Cosmic Environments of Quasars in the First Gyr of the Universe (Other)"^^ . . . . . . "small.jpg"^^ . . . "The Physical Properties and Cosmic Environments of Quasars in the First Gyr of the Universe (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #25125 \n\nThe Physical Properties and Cosmic Environments of Quasars in the First Gyr of the Universe\n\n" . "text/html" . . . "520 Astronomie"@de . "520 Astronomy and allied sciences"@en . .