On Filaments within Molecular Clouds and their Connection to Star
  Formation
  In recent years, there were studies on the omnipresence and structures of
filaments in star-forming regions, and the role of their fragmentation in the
process of star formation. However, only a few studies analysed the evolution
of filaments and their distribution with the Galactic disk where filaments form
self-consistently as part of large-scale molecular cloud evolution. In this
thesis, I perform dust radiative transfer calculations to study the effect of
inclination on dust observations of filaments to evaluate whether the
variations enable the identification of more filaments within dust surveys. I
address the early evolution of pc-scale filaments that form within individual
clouds and focus on how and when the filaments fragment, and how the
fragmentation relates to typically used observables. For evaluating the
equilibrium state of filaments and the nature of their fragmentation I examine
three simulated molecular clouds formed in kpc-scale numerical simulations
modelling a self-gravitating, magnetised, stratified, supernova-driven ISM. The
first fragments appear when the line masses of the simulated filaments lie well
below the critical line mass of Ostrikers isolated hydrostatic equilibrium
solution. This indicate that, although the turbulence of the entire clouds is
mostly driven by gravitational contraction, fragmentation does not occur do to
gravitational instability, but is supported by colliding flow motions. I
conclude that there is no single quantity in my analysis that can uniquely
trace the inclination and 3D structure of a filament based on dust observations
alone. A simple model of an isolated, isothermal cylinder may not provide a
good approach for fragmentation analysis, independently of the dominant driving
source of the parental cloud.
