deletions | additions
diff --git a/sectionMethdology_To.tex b/sectionMethdology_To.tex
index 957e8f8..32d6717 100644
--- a/sectionMethdology_To.tex
+++ b/sectionMethdology_To.tex
...
\item{Projected aspect ratio $\ge 50:1$}
\end{enumerate}
The name and coordinates for these ten filaments, along with their average LSR velocities, the number of bone criteria they satisfy, and a "quality rating" are listed in figure \ref{fig:candidates}. In figure \ref{fig:mass_of_bones}, we summarize physical parameters for all ten bone candidates, including estimates of distance, volume, mass, and aspect ratio. We calculate mass by \textit{estimating} an average H$_2$ column density of $2 \times 10^{22}$ cm$^{-2}$, consistent with the minimum IRDC peak column density to be included in the \citet{Peretto_2009} catalog of 11,303 IRDCs. We calculate distances assuming all of our bone candidates (see Figure \ref{fig:skeleton}) are associated with the \citet{Dame_2011} Scutum-Centaurus arm.
Two candidates, BC\_21.25-0.15 and BC\_11.13-0.12 show potential association with the Norma-4kpc arm; to confirm their distances, When available, we
use the the catalog also provide distance measurements from
\citet{Ellsworth_Bowers_2013}, the \citet{Ellsworth_Bowers_2013} catalog, which provides distances to 1710 molecular clouds from the BGPS survey, derived using a Bayesian distance probability density function.
The \citet{Ellsworth_Bowers_2013} derived distance to BC\_11.13-0.12 agrees with our \citet{Dame_2011} distance within estimated errors, while BC\_21.25-0.15 falls slightly outside the acceptable error range (see figure \ref{fig:mass_of_bones}).
Of the ten filaments with velocities consistent with galactic rotation, \textbf{six} of these meet all six bone criteria: \textbf{BC\_26.94-0.30, BC\_25.24-0.45, BC\_18.88-0.09, BC\_4.14-0.02, BC\_335.31-0.29, and BC\_332.21-0.04}, to varying degrees of excellence. We note that BC\_332.21-0.04 has likely been disrupted by stellar feedback, making its aspect ratio and velocity structure more difficult to define. Since we predict that all galactic bones will likely be destroyed by stellar feedback and/or galactic shear, we include it here as part of a larger attempt to build a catalog of bones at all stages of their evolution. We also include BC\_335.31-0.29, even though it has a $p-v$ orientation perpendicular to predicted fits of the Scutum-Centaurus arm (see Figure \ref{fig:skeleton}). As spurs and inter-arm structures are likely to lie close to the physical Galactic mid-plane, but with velocity gradients angled with respect to predicted arm fits, we do {\it not} require that a bone be parallel to arm $p-v$ traces, so as not to exclude potential spurs, feathers, or other inter-arm features.
Of the four remaining filaments that do not meet all six
criteria---BC\_357.62-0.33, BC\_11.13-0.1, BC\_24.96-0.17, criteria---BC\_24.96-0.17, BC\_21.25-0.15, BC\_11.13-0.12, and
BC\_21.25-0.15---all BC\_357.62-0.33---all of them fail criterion 6 (aspect ratio $\ge 50:1$). As our criterion 6 does not allow for projection effects in imposing an aspect ratio limit, we emphasize that those filaments lying more tangential to our line-of-sight will appear foreshortened, and could very well meet the 50:1 minimum limit if projection effects were removed. We plan to examine the the aspect ratios of all our candidates in a follow-up study, accounting for expected projection effects if they lie along the nearest spiral arm.
Of Two of these
four candidates, filaments BC\_24.96-0.17 and BC\_357.62-0.33
shows show particular promise,
both lying within 2-3 pc of the physical Galactic midplane
and situated on a prominent peak of CO emission in \textit{p-p} space (see
appendix section BC\_357.62-0.33). appendix), though BC\_24.96-0.17 does lie at the upper limit of criterion 4, and its \citet{Ellsworth_Bowers_2013} derived distance places it 1 kpc closer than the distance derived from the \citet{Dame_2011} Scutum-Centaurus fit. The
second third filament, BC\_11.13-0.12 ("the snake"), has already been well-studied from a star formation perspective, hosting over a dozen protostellar cores likely to produce regions of high-mass star formation \citep{Wang_2014,Henning_2010}. From a Galactic bone perspective, the snake strongly satisfies all criteria except number 6---it lies within 15 pc of the physical galactic midplane and 5 km/s from the \citet{Dame_2011} Scutum-Centaurus global-log fit to CO, tracing a prominent peak of the Scutum-Centaurus arm in \textit{p-v} space (see appendix section BC\_11.13-0.12). The
third and fourth
candidates---BC\_024.96-0.17 and BC\_021.25-0.15---are filament, BC\_21.25-0.15 is arguably the
two weakest
candidates, awarded a quality rating of "C". BC\_024.96-0.17 lies 10 km/s from the \citet{Shane_1972} fit to HI for the Scutum-Centaurus arm, at the top limit of
our criterion 4, while BC\_21.25-0.15 looks to be a potential interarm feature. There all ten candidates: there is
also a slight break in the extinction feature
near a longitude of
BC\_021.25-0.15, though both sides of the filament are contiguous $21.25^\circ$, and its placement in
velocity. \textit{p-v} space suggests it is possibly an interarm filament (see appendix).
In summary, it is important to emphasize that some of the above criteria will likely be modified in the long run, as we learn more about the Skeleton of the Milky Way. Given our limited a priori knowledge of the Galaxy's structure, it is presently easier to confirm Bones that are spine-like, lying along arms with velocities predicted by extant modeling (criteria 1, 5), and harder to find spurs off those arms or inter-arm features (e.g. BC\_335.31-0.29), the velocities of which are hard to predict well. Similarly, since criterion 6 does not allow for projection effects in imposing an aspect ratio limit, bones which otherwise meet all criteria could fail if they lie close to the tangents of spiral arms. As we learn more about spiral structure from simulations and modeling, these criteria will also be adjusted to allow for bone-like features that represent spurs, inter-arm structures, and/or foreshortened structures lying close to our line of sight.
