Gravitational Infall onto Molecular Filaments II. Externally Pressurized
  Cylinders
  In an extension of Fischera & Martin (2012a) and Heitsch (2013), two aspects
of the evolution of externally pressurized, hydrostatic filaments are
discussed. (a) The free-fall accretion of gas onto such a filament will lead to
filament parameters (specifically, FWHM--column density relations) inconsistent
with the observations of Arzoumanian et al. (2011), except for two cases: For
low-mass, isothermal filaments, agreement is found as in the analysis by
Fischera & Martin (2012b). Magnetized cases, for which the field scales weakly
with the density as $B\propto n^{1/2}$, also reproduce observed parameters. (b)
Realistically, the filaments will be embedded not only in gas of non-zero
pressure, but also of non-zero density. Thus, the appearance of sheet-embedded
filaments is explored. Generating a grid of filament models and comparing the
resulting column density ratios and profile shapes with observations suggests
that the three-dimensional filament profiles are intrinsically flatter than
isothermal, beyond projection and evolution effects.
