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Abstract

This thesis is dedicated to the characterization of the physical and chemical properties in high-mass star-forming regions. I use interferometric observations at 1 and 3 mm wavelengths with the NOrthern Extended Millimeter Array (NOEMA) and Atacama Large Millimeter/submillimeter Array (ALMA) of a sample of high-mass star-forming regions at different evolutionary stages ranging from infrared dark clouds, high-mass protostellar objects, hot molecular cores, to ultra-compact HII regions. At angular resolutions <1 arcsec, the physical and chemical properties of individual fragmented cores can be studied on scales <0.1 pc using both continuum and molecular line emission. Molecule properties, for example, the column density and rotation temperature, are derived using the eXtended CASA Line Analysis Software Suite (XCLASS) of species such as SO, OCS, SiO, H2 CO, CH3CN, and CH3OH. I determine for a statistical sample of cores radial temperature and density profiles (T ∼ r^-q and n ∼ r^-p , respectively), masses M, and molecular column densities N. Chemical timescales τchem are estimated using the physical-chemical model MUlti Stage CLoud codE (MUSCLE). There is a high degree of fragmentation in the regions and the spatial morphology of the continuum emission is diverse, where in some regions there is a single isolated core, while in other regions, for example, filamentary structures that have many embedded cores are found. The molecular content of individual cores have local chemical variations and with MUSCLE this chemical differentiation can be explained by the cores being at slightly different evolutionary stages. By combining the results of the in total 31 high-mass star-forming regions that were observed with either NOEMA or ALMA at high angular resolution and that were analyzed within this thesis, evolutionary trends of the physical core properties are found. The temperature profile q steepens from q ≈ 0.1 to q ≈ 0.7 and the density profile p1 on clump scales (0.1 - 1 pc) flattens from p1 ≈ 2.2 to p1 ≈ 1.2 with time as the cores evolve. No evolutionary trend is found for the density profile p2 on core scales (<0.1 pc), with p2 ≈ 2, indicating that all of the analyzed cores are collapsing to form (high-mass) stars. These results provide invaluable observational constraints to test theoretical formation models of high-mass stars.