A PPMAP analysis of the filamentary structures in Ophiuchus L1688 and
  L1689
  We use the PPMAP (Point Process MAPping) algorithm to re-analyse the
\textit{Herschel} and SCUBA-2 observations of the L1688 and L1689 sub-regions
of the Ophiuchus molecular cloud. PPMAP delivers maps with high resolution
(here $14''$, corresponding to $\sim 0.01\,{\rm pc}$ at $\sim 140\,{\rm pc}$),
by using the observations at their native resolutions. PPMAP also delivers more
accurate dust optical depths, by distinguishing dust of different types and at
different temperatures. The filaments and prestellar cores almost all lie in
regions with $N_{\rm H_2}\gtrsim 7\times 10^{21}\,{\rm cm}^{-2}$ (corresponding
to $A_{_{\rm V}}\gtrsim 7$). The dust temperature, $T$, tends to be correlated
with the dust opacity index, $\beta$, with low $T$ and low $\beta$ tend
concentrated in the interiors of filaments. The one exception to this tendency
is a section of filament in L1688 that falls -- in projection -- between the
two B stars, S1 and HD147889; here $T$ and $\beta$ are relatively high, and
there is compelling evidence that feedback from these two stars has heated and
compressed the filament. Filament {\sc fwhm}s are typically in the range
$0.10\,{\rm pc}$ to $0.15\,{\rm pc}$. Most filaments have line densities in the
range $25\,{\rm M_{_\odot}\,pc^{-1}}$ to $65\,{\rm M_{_\odot}\,pc^{-1}}$. If
their only support is thermal gas pressure, and the gas is at the canonical
temperature of $10\,{\rm K}$, the filaments are highly supercritical. However,
there is some evidence from ammonia observations that the gas is significantly
warmer than this, and we cannot rule out the possibility of additional support
from turbulence and/or magnetic fields. On the basis of their spatial
distribution, we argue that most of the starless cores are likely to disperse
(rather than evolving to become prestellar).
