deletions | additions       diff --git a/ch_h2co.tex b/ch_h2co.tex  index a9390db..24fe795 100644  --- a/ch_h2co.tex  +++ b/ch_h2co.tex 
...
and follow-up work comparing to different lines (i.e., CO) is necessary to  cleanly demonstrate the observed effect.  It turns out the property of turbulence I have measured here has been discussed   under other terminology. \citet{Hennebelle2012a} describe the boundaries between  GMCs in the cold neutral medium and the surrounding warm neutral medium. In their  description, GMCs consist of low volume-filling-factor cold clumps interspersed  within a warm ($\sim10^4$ K) medium. \citet{Williams1995a} measure the inter-clump  medium density as $n\sim4 \percc$.  \section{Abstract}  We present a pilot survey of 21 lines of sight towards ultracompact \ion{H}{2}  diff --git a/introduction.tex b/introduction.tex  index 558cca6..3becf83 100644  --- a/introduction.tex  +++ b/introduction.tex 
...
scale-free and defining the distribution of velocities, densities,  temperatures, and magnetic fields in the gas between stars.  Turbulence forms in fluids when the inertial force greatly exceeds the  viscosity. It creates instabilities in the fluid that start on large scales  and ``cascade'' energy to smaller scales. Once a small enough size-scale is  reached, the viscosity exceeds the interial force and the energy heats the  fluid on local scales.  Turbulence is most easily modeled by a Kolmogorov spectrum, in which $\Delta v  \propto \ell^{1/3}$, i.e. the typical velocity dispersion is greatest at the  largest size scales. Kolmogorov turbulence strictly only describes  incompressible fluids without magnetic fields, while the ISM is compressible  and threaded by magnetic fields. Nonetheless, Kolmogorov turbulence is nearly  consistent with some observed properties of the ISM. The Larson size-linewidth  relation, relation ($\sigma_{\kms}\approx1.1 L_{pc}^{0.38}$),  in particular, is similar to that predicted by Kolmogorov turbulence. Turbulence is often quoted as a source of \emph{pressure} based on the  Kolmogorov description. At size scales much smaller than the driving scale of 
...
and can add support against gravitational collapse.   However, turbulence decays rapidly. The turbulent decay timescale  $\tau_{decay}\propto L \ell  / v$, where $L$ $\ell$  is the turbulent length scale and $v$ is the velocity scale. It therefore increases with size scale as  $\tau_{decay}\propto L^{2/3}$. \ell^{2/3}$.  Turbulence decays most quickly on the smallest timescales. sizescales.  We are therefore left with two conditions: Turbulence must be driven at large  scales for turbulence to provide support against gravity, gravity\footnote{Once stars form  in a cloud and stellar feedback becomes significant, turbulence can be driven at all  scales, but the turbulent support needed to slow or prevent the initial  collapse of starless cores cannot be driven by local stars.},  and it must be constantly driven to resupply the turbulence that is transferred to heat on the  smallest scales.  Once stars form, however, large-scale driving of turbulence may not be the  dominant shaping mechanism for the gas. Outflows from low-mass stars, soft UV  from B stars, and ionizing UV and strong winds from OB stars can drive gas  motions, disrupting gas or replenishing turbulent energy. Once stars have  formed in a cloud, feedback rather than turbulence is likely to govern the  future evolution of the cloud.  Because the ISM is compressible, interacting flows within the turbulent medium  will result in density enhancements and voids. Many simulation studies have  determined that the resulting density distribution, and correspondingly the  column-density distribution, should be approximately log-normal. Observational  studies agree that in regions not yet significantly affected by gravity, the   column-density distribution is log-normal. In regions where stars are actively  forming, i.e. regions in which gas self-gravity has affected a significant fraction  of the gas,  a high-density power-law tail forms. One theory of star formation holds that the initial mass function of stars is  determined entirely by turbulence. In this description, the highest  overdensities in the turbulent medium become gravitationally unstable and  separate from the turbulent flow as they collapse into proto-stellar cores.  This idea has been a hot topic in the past few years, but I will not address  it directly in this thesis.  In the W5 and IRAS 05358 regions (Chapter \ref{ch:w5} and  \citet{Ginsburg2009}), I examined outflows as potential drivers of turbulence.  In IRAS 05358, I concluded that the outflows could provide the observed  turbulence in the $\sim$pc-scale `clump', but that the central core had energy  dissipation much faster than turbulence could be resupplied. In W5, I rule out  protostellar outflows as a significant driver of turbulence.  In Chapter \ref{ch:h2co}, I examine the density probability distribution  function (PDF) in giant molecular clouds (GMCs). Because \formaldehyde is  uniquely capable of measuring local volume density, I was able to place  interesting constraints on the density PDFs in non-star-forming GMCs, namely  that they are unlikely to be the simple log-normal distributions expected from  isothermal incompressible turbulence.  \subsection{Mass Functions}  \label{sec:massfunctions}  Perhaps the most fundamental goal of star formation studies is to determine the  Initial Mass Function (IMF) of stars and what, if anything, causes it to vary.  It is also one of the most challenging statistically and observationally. 
...
emission maps. The CMF has a similar functional form to the IMF, but its mean  is higher by a factor $\sim3$ in local star forming regions, leading to the claim  that star formation proceeds from CMF->IMF with 30\% efficiency.  This idea has recently been explored theoretically by \citet{Chabrier2010a} and  \citet{Hopkins2012b} and observationally by the Herschel Gould's Belt team  \citep{Arzoumanian2011a,Andre2010a}.  Gas clouds follow a mass function that extends up to the largest  possible coherent scales, giant molecular clouds with scales $\sim50-100$ pc 
...
some intermediate state of the gas that is drawn from an intermediate  distribution, shallower than `cores' but steeper than `clouds'.   The BGPS (Chapter \ref{ch:v2}) presents the first real opportunity to explore  the mass function of clumps on scales intermediate between cores and giant  clouds. While I do not explicitly examine core or clump mass functions in this  thesis, their measurement is an important motivation for the large-area surveys  we have performed.  \subsubsection{Clusters}  Clusters are also drawn from a mass function comparable to stars, but  ironically their distribution is better measured than for stars. Clusters are easily visible - and resolvable - in other galaxies, and massive clusters are  less likely to be embedded than massive stars. In normal galaxies, cluster  populations are consistent with a Schechter distribution: a power-law  $\alpha\sim2$ with an exponential cutoff at large masses.  $$N(M)dM = C M^{-2} e^{-M} dM$$  Since clusters are not drawn from the same parent distribution as GMCs (which  have $\alpha\sim1$), $\alpha\sim1$, so $N(M) dM = C M^{-1} dM$),  it is plausible that their precursors are, instead, the intermediate-scale `clumps' observed in the millimeter continuum. However, the clump mass function has yet to be measured, so even this first step of determining plausibility is incomplete. Clusters are an important observational tool in astrophysics. For stellar  studies, they have been used to select populations of co-eval stars. In  extragalactic studies, they are frequently the smallest observable individual  units. However, many recent works have pointed out that clusters may be  short-lived, transient phenomena. phenomena  \citep{Kruijssen2011a,Whitehead2013a,Gieles2011a,Whitmore2009a}.  Any study of their populations must take in to account their dissolution. The most massive clusters, however, are both the most easily observed and the longest lived, and therefore provide some of the most useful tools for understanding stars. As with massive stars, massive clusters are rare. Only a handful of young  massive clusters are known within our Galaxy, including the most massive, NGC 
...
is effectively unconstrained. The incomplete knowledge of clusters is due to  extinction and confusion within the plane.  In Chapter \ref{ch:ympc}, I search the BGPS for candidate proto-massive star  clusters. Because the Galactic disk is optically thin at 1.1 mm, a complete  census of proto-clusters is possible.  %\subsection{Galactic Plane Surveys}  %The idea to observe the plane of the Galaxy is not new.  diff --git a/thesis.bib b/thesis.bib  index 70837b6..962816a 100644  --- a/thesis.bib  +++ b/thesis.bib 
...
  @article{Whitmore2009a,  Author = {{Whitmore}, B.~C.},  Journal = {\apss},  Month = dec,  Pages = {163-169},  Title = {{The life and death of star clusters}},  Volume = 324,  Year = 2009}  @article{Gieles2011a,  Author = {{Gieles}, M. and {Heggie}, D.~C. and {Zhao}, H.},  Journal = {\mnras},  Month = jun,  Pages = {2509-2524},  Title = {{The life cycle of star clusters in a tidal field}},  Volume = 413,  Year = 2011}  @article{Kruijssen2011a,  Author = {{Kruijssen}, J.~M.~D. and {Pelupessy}, F.~I. and {Lamers}, H.~J.~G.~L.~M. and {Portegies Zwart}, S.~F. and {Icke}, V.},  Journal = {\mnras},  Month = jun,  Pages = {1339-1364},  Title = {{Modelling the formation and evolution of star cluster populations in galaxy simulations}},  Volume = 414,  Year = 2011}  @article{Whitehead2013a,  Author = {{Whitehead}, A.~J. and {McMillan}, S.~L.~W. and {Vesperini}, E. and {Portegies Zwart}, S.},  Journal = {ArXiv e-prints},  Month = mar,  Title = {{Simulating Star Clusters with the AMUSE Software Framework: I. Dependence of Cluster Lifetimes on Model Assumptions and Cluster Dissolution Modes}},  Year = 2013}    @article{Arzoumanian2011a,  Author = {{Arzoumanian}, D. and {Andr{\'e}}, P. and {Didelon}, P. and {K{\"o}nyves}, V. and {Schneider}, N. and {Men'shchikov}, A. and {Sousbie}, T. and {Zavagno}, A. and {Bontemps}, S. and {di Francesco}, J. and {Griffin}, M. and {Hennemann}, M. and {Hill}, T. and {Kirk}, J. and {Martin}, P. and {Minier}, V. and {Molinari}, S. and {Motte}, F. and {Peretto}, N. and {Pezzuto}, S. and {Spinoglio}, L. and {Ward-Thompson}, D. and {White}, G. and {Wilson}, C.~D.},  Journal = {\aap},  Month = may,  Pages = {L6},  Title = {{Characterizing interstellar filaments with Herschel in IC 5146}},  Volume = 529,  Year = 2011}  @article{Andre2010a,  Author = {{Andr{\'e}}, P. and {Men'shchikov}, A. and {Bontemps}, S. and {K{\"o}nyves}, V. and {Motte}, F. and {Schneider}, N. and {Didelon}, P. and {Minier}, V. and {Saraceno}, P. and {Ward-Thompson}, D. and {di Francesco}, J. and {White}, G. and {Molinari}, S. and {Testi}, L. and {Abergel}, A. and {Griffin}, M. and {Henning}, T. and {Royer}, P. and {Mer{\'{\i}}n}, B. and {Vavrek}, R. and {Attard}, M. and {Arzoumanian}, D. and {Wilson}, C.~D. and {Ade}, P. and {Aussel}, H. and {Baluteau}, J.-P. and {Benedettini}, M. and {Bernard}, J.-P. and {Blommaert}, J.~A.~D.~L. and {Cambr{\'e}sy}, L. and {Cox}, P. and {di Giorgio}, A. and {Hargrave}, P. and {Hennemann}, M. and {Huang}, M. and {Kirk}, J. and {Krause}, O. and {Launhardt}, R. and {Leeks}, S. and {Le Pennec}, J. and {Li}, J.~Z. and {Martin}, P.~G. and {Maury}, A. and {Olofsson}, G. and {Omont}, A. and {Peretto}, N. and {Pezzuto}, S. and {Prusti}, T. and {Roussel}, H. and {Russeil}, D. and {Sauvage}, M. and {Sibthorpe}, B. and {Sicilia-Aguilar}, A. and {Spinoglio}, L. and {Waelkens}, C. and {Woodcraft}, A. and {Zavagno}, A.},  Journal = {\aap},  Month = jul,  Pages = {L102},  Title = {{From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt Survey}},  Volume = 518,  Year = 2010}  @article{Chabrier2010a,  Author = {{Chabrier}, G. and {Hennebelle}, P.},  Journal = {\apjl},  Month = dec,  Pages = {L79-L83},  Title = {{Star Formation: Statistical Measure of the Correlation between the Prestellar Core Mass Function and the Stellar Initial Mass Function}},  Volume = 725,  Year = 2010}  @article{Hopkins2012b,  Author = {{Hopkins}, P.~F.},  Journal = {\mnras},  Month = jul,  Pages = {2037-2044},  Title = {{The stellar initial mass function, core mass function and the last-crossing distribution}},  Volume = 423,  Year = 2012}    @article{Hennebelle2012a,  Author = {{Hennebelle}, P. and {Falgarone}, E.},  Journal = {ArXiv e-prints},  Month = nov,  Title = {{Turbulent molecular clouds}},  Year = 2012}  @article{Williams1995a,  Author = {{Williams}, J.~P. and {Blitz}, L. and {Stark}, A.~A.},  Journal = {\apj},  Month = sep,  Pages = {252},  Title = {{The Density Structure in the Rosette Molecular Cloud: Signposts of Evolution}},  Volume = 451,  Year = 1995}  @article{Mangum2013a,  Author = {{Mangum}, Jeffrey~G. and {Darling}, Jeremy and {Henkel}, Christian and {Menten}, Karl~M.},  Month = {Feb},  diff --git a/thesis.tex b/thesis.tex  index 0f3da2c..dc2817f 100644  --- a/thesis.tex  +++ b/thesis.tex 
...
%%%%%%%%%%%% all the preamble material: %%%%%%%%%%%%  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  \title{Star \title{Surveying Star  Formation in the Galaxy} \author{Adam G.}{Ginsburg}