The Survival of Multiphase Dusty Clouds in Hot Winds. (arXiv:2107.07991v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Farber_R/0/1/0/all/0/1">Ryan Jeffrey Farber</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gronke_M/0/1/0/all/0/1">Max Gronke</a>
Much progress has been made recently in the acceleration of $sim10^{4}$ K
clouds to explain absorption-line measurements of the circumgalactic medium and
the atomic phase of galactic winds. However, the origin of the molecular phase
in galactic winds has received relatively little theoretical attention. Studies
of the survival of atomic clouds suggest efficient radiative cooling may enable
the survival of expelled material from galactic disks. Alternatively, atomic
and molecular gas may form within the outflow, if dust survives the
acceleration process. We explore the survival of molecular, dusty clouds in a
hot wind with three-dimensional hydrodynamic simulations in which we include
radiative cooling and model dust as tracer particles. We find that molecular
gas can be destroyed, survive, or transformed entirely to $sim 10^4$ K gas. We
establish analytic criteria distinguishing these three outcomes which compare
characteristic cooling times to the `cloud crushing’ time of the system. In
contrast to typically studied atomic $sim10^{4}$ K clouds, molecular clouds
are entrained faster than the drag time as a result of efficient mixing.
Moreover, we find that while dust can in principle survive embedded in the
accelerated clouds, the survival fraction depends critically on the time dust
spends in the hot phase and on the effective threshold temperature for
destruction. We discuss our results in the context of polluting the
circumgalactic medium with dust and metals, as well as understanding
observations suggesting rapid acceleration of molecular galactic winds and ram
pressure stripped tails of jellyfish galaxies.
Much progress has been made recently in the acceleration of $sim10^{4}$ K
clouds to explain absorption-line measurements of the circumgalactic medium and
the atomic phase of galactic winds. However, the origin of the molecular phase
in galactic winds has received relatively little theoretical attention. Studies
of the survival of atomic clouds suggest efficient radiative cooling may enable
the survival of expelled material from galactic disks. Alternatively, atomic
and molecular gas may form within the outflow, if dust survives the
acceleration process. We explore the survival of molecular, dusty clouds in a
hot wind with three-dimensional hydrodynamic simulations in which we include
radiative cooling and model dust as tracer particles. We find that molecular
gas can be destroyed, survive, or transformed entirely to $sim 10^4$ K gas. We
establish analytic criteria distinguishing these three outcomes which compare
characteristic cooling times to the `cloud crushing’ time of the system. In
contrast to typically studied atomic $sim10^{4}$ K clouds, molecular clouds
are entrained faster than the drag time as a result of efficient mixing.
Moreover, we find that while dust can in principle survive embedded in the
accelerated clouds, the survival fraction depends critically on the time dust
spends in the hot phase and on the effective threshold temperature for
destruction. We discuss our results in the context of polluting the
circumgalactic medium with dust and metals, as well as understanding
observations suggesting rapid acceleration of molecular galactic winds and ram
pressure stripped tails of jellyfish galaxies.
http://arxiv.org/icons/sfx.gif
