Catherine Zucker edited sectionMethdology_To.tex  about 9 years ago

Commit id: 5dc7f24e9621d2b71ac8f9a18ced039449761bfb

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\item{Projected aspect ratio $\ge 50:1$}  \end{enumerate}  In figure \ref{fig:mass_of_bones}, we summarize physical parameters for our bones, including the distance, volume, mass, and aspect ratio. We conservatively estimate an $\rm{H}_2$ column density of 1E22, consistent with the minimum H2 $\rm{H}_2$  column density required for an IRDC to be included the \citet{Peretto_2009} study of 11,303 infrared clouds. We plan to directly measure these quantities this quantity  in follow-up studies, using the 8 $\mu\textrm{m}$ imaging data from the GLIMPSE survey to create our column density and temperature maps for our candidates. 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}, with varying degrees of excellenge. However, it is important to note 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 find 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, the velocities of which are hard to predict well. Similarly, criterion 6 does not allow for projection effects in imposing an aspect ratio limit. 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.