Discussion Section Falgarone Reynolds Cox Meyer Spangler Deshpande

Discussion Section Falgarone, Reynolds, Cox, Meyer, Spangler, Deshpande, Goss, Stanimirovic, Heiles BUT…. . It’s more fun to do this together!

QUESTIONS: 1. Are various flavors of TSAS related? 2. Are we converging on TSAS abundance & properties? 3. TSAS Observations confront theory/simulat. 4. “Things” vs statistical fluctuations? 5. Is the over-pressure problem resolved? 6. Survival of tiny-scale structures. 7. Power Spectrum from different media? 8. How can we improve communications? 9. Where do we go from here? 10. TSAS and the Big Picture? 11. Filaments vs sheets vs ribbons vs strings… 12. Revealing Local Neighborhood

1. Various flavors of TSAS…. . Atomic TSAS Molecular TSAS Ionized TSAS Are these different phenomena ? How can we observationally probe possible connections? Are ionized TSAS outer edges of neutral TSAS? Several suggestions for self-gravitating TSAS.

2. Are we converging on TSAS abundance & properties? VLBA: common but small filling factor Pulsars: rare and could be sampling special conditions Low-N(HI): common on scales of a few x 103 AU. Na. I: rare + shells + cloud edges Molecular: common in diffuse medium Ionized: very common Ubiquitous --> common --> special conditions/events ? ? ?

3. Observations of TSAS vs theory/simulations. Recent observations show TSAS is rare/small filling factor/common, while theory/simulations show lots of TSAS. How can we constrain theory/simulations (large M vs partially ionized gas vs dynamical triggering vs shear flows vs new types of turbulence)? Which parameters are needed?

4. “Things” vs statistical fluctuations? What are these structures? Several examples of a possible shell/stellar wind connection. How can we observationally distinguish “structures” from “statistical fluctuations”? “Duality” of existence?

5. Is the over-pressure problem resolved? Is it understood why/how can certain (what? ) fraction of gas be at high pressure? How does this compare with observations? 6. Survival of tiny-scale structures: Conduction vs turbulence vs dynamics vs magnetic field? How can we determine what is the key factor ?

7. Power Spectrum from different media? How different are PS slopes and what is this telling us? HI emission: ~3. 7 HI absorption: 2. 8 Optical, IR (Gibson): 2. 8 IR: 3. 5, @0. 3 pc --> 2. 7 H 2) masers 3. 7 DM, SM: 3. 7 DM (Terzan 5): ~3. 7 - And what does Kolmogorov spectrum actually mean? - Does it imply turbulence or other processes? - How can we observationally probe turbulent dissipation scales?

8. How can we improve communications: (a) between various observational techniques? (b) between observations/theory/simulations?

10. Big Picture? What are we trying to answer? And what is the big picture? Importance of TSAS for other ISM studies? What are the implications/directions for future ISM studies?

9. Where do we go from here? What are the key future observations? How to detect CNM/WNM interfaces for example? New telescopes --- what do we really need (SKA, E-VLA, ALMA, starlight polarization instrument? )? What are the key future theoretical/numerical developments? Is resolution good enough? Initial conditions?

11. Filaments vs sheets vs ribbons vs strings… Both simulations and observations show a lot of “filamentary structure” with large aspect ratios. Is the entire ISM “stringy”? Why? What would be the key observations to test this? What causes very thin scattering screens? What causes anisotropic scintels? 12. Revealing Local Neighborhood Local clouds + local screens + IS weather & climate

Thank you so much for participating in the meeting !!! And many thanks to NRAO for wonderful hospitality !!!! • Especially: Miller Goss, Dale Frail Jean Pierre Marquart, Nissim Kanekar Skip Lagoyda, Terry Romero & Kathy Young

And special thanks to: SOC Members • • • Crystal Brogan, University of Hawaii Don Cox, University of Wisconsin Madison Avinash Deshpande, Raman Research Institute Edith Falgarone, LERMA Paris Miller Goss, NRAO Carl Heiles, University California Berkeley (co-chair) Dave Meyer, Northwestern University Ron Reynolds, University of Wisconsin Madison Barney Rickett, University California San Diego Dan Stinebring, Oberlin College