Theme IV: Nearby Galaxies and the Galactic Center

1. G.J. Stacey Cornell University Theme IV: Nearby Galaxies and the Galactic Center

2. Team Members • Gordon Stacey (Cornell) Formal Lead • Science: Far-IR and submm spectroscopy of galaxies, Galactic starformation regions, Galactic Center • Experience: KAO/ISO/JCMT – CSO • Investments: SOFIA (FORCAST/SAFIRE) • Unique Strength: Submm lines, Instrumentation • Bill Vacca (USRA) SOFIA Lead • Science: UV/Optical/Near IR spectroscopy & photometry galaxies, star clusters, massive stars • Experience: HST/Keck/IRTF/Gemini/Spitzer • Investments: SOFIA • Unique Strength: Optical studies, Stellar Populations

3. Team Members • Sue Madden (CEA/Saclay) • Science: Mid/far-IR and spectroscopy and photometry of galaxies , Galactic starformation regions, Galactic Center • Experience: KAO/ISO (LWS/ISOCAM) • Investments: Herschel (SPIRE/PACS) • Unique Strength: Dwarf Galaxies, Dust continuum • Mark Morris (UCLA) • Science: Multi-wavelength studies of the Galactic Center • Experience: KAO/VLA/HST/Keck/Chandra/Spitzer • Investments: SOFIA • Unique Strength: Galactic Center

4. Team Members • Linda Tacconi (MPE) • Science: Multi-wavelength spectroscopy of active galaxies AGN/high z galaxies • Experience: FCRAO/JCMT/VLT/ISO(SWS) Spitzer IRAM Interferometer • Investments: Herschel (PACS) • Unique Strength: Molecular gas in high z galaxies • Mark Wolfire (Maryland) • Science: Theory – PDR/XDR and HII region modeling – Galactic starformation regions, Galactic Center, galaxies • Experience: KAO/ISO/Spitzer • Investments: SOFIA • Unique Strength: Theory, modeling

5. Activities • Team assembled in April/May • First Telecon in late May • Discussion of scope of our assignment – where do we fit in? • Discussion of science topics • Discussion of timelines • Telecons scheduled for Wednesdays at noon eastern time

6. Where do we fit in? • Whitepaper generated by a group led by Erick Young • Two page section on extragalactic work • January 2008 AAS SOFIA Workshop Whitepaper (Bob Gehrz-led) • 4 page section on extragalactic and Galactic Center work with SOFIA • 2005 SOFIA Science Cases (Tom Greene) • Section on Galactic Center • Section on HAWC observations of the distant Universe • Section on nearby Galaxies How do we fit in?

7. Goals/Schedule June 18 July 16 August 13 October 1 • Create a list of science topics well addressed by SOFIA • Define the unique capabilities of SOFIA within its current instrumentation • Within the science list, compare the capabilities of SOFIA and contemporaneous facilities (e.g. Herschel) and near future facilities (e.g. JWST) • How can second generation SOFIA instruments tip the balance • Refine science topics • Prepare document • Prepare PPT slides

8. Example: Nearby Galaxies Interstellar Gas and the Stellar Life Cycle Primordial gas Cooling, contractionchemistry Diffuse interstellar gas H, He, C+, O Dense interstellarclouds H2, He, CO Contraction,gravitational instability Windsstellar explosions Star formation Stellar evolution Stellar remnants

9. Beam at [OI] SAFIRE FOV Example: Nearby Spiral Galaxies • Morphologies • Elemental abundances • Dust parameters • Requires high spatial resolution • Key elements • Wide-field mapping – mapping speed • Spatial registration between lines/continuum etc. • Sensitivity • Variety of lines available and dust SEDs

10. SOFIA Strengths • Mapping capabilities • Large field of view for cameras (e.g. FORCAST 33’ FOV, SAFIRE FPI ~ 2.75.3’ FOV) What are the relative mapping speeds of SOFIA/Herschel for typical nearby galaxies – SOFIA efficiencies twice as high! • Large chopper throw essential for mapping large nearby galaxies (SOFIA 10’ vs. 6’ for Herschel) How does this effect Hershel source list? • Resolving power uniquely high between 5 to 28 and 100 to 700 m (SAFIRE, FPI) Advantages of EXES and SAFIRE? Resolved lines to distinguish ISM components

11. SOFIA Strengths • Wavelength coverage • 9 octaves of wavelength coverage (1 to 700 m) • Post-Spitzer near unique coverage from ~5 m (until JWST) through 60 m (Herschel) • Covers the peak of dust SED in starburst galaxies • Host of lines from 5 to 60 m including (post Spitzer) SOFIA unique lines: [SIII] (33 m), [SiII] (35 m), [NeIII] (36 m), [OIII] (52 m), [NIII] (57 m), in the 30 to 60 m band • Resolve and map far-IR lines with SAFIRE including unique ones beyond 200 m: [NII], [CII] [OI], mid and high J CO (but mid-J CO and [CI] easy from the ground…) • PDRs, HII regions, shocks, galactic tori, warm dense molecular/neutral gas

12. Evolution of Galaxies • Near unique niches for studying the epoch from the peak of the star formation per unit volume through to today’s universe • z ~ 0 to 1 for [CII] 158 m line – major gas coolant, probes PDRs, G, intensity, size of starburst • z ~ 0 to 1 for [NII] 205 m line – probes low density HII regions, proxy for Lyman continuum photons, separates [CII] fraction from ionized gas. • z > 2 [OI] 63 m studies – major PDR gas coolant, probes dense PDRs, G, size of starburst • SAFIRE is quite competitive with Herschel (especially if SAFIRE is a grating spectrometer – otherwise a next generation spectrometer can fully exploit this sensitivity niche)

13. 5  in 2 hours – ULIRG line to continuum ratios: Adjusted to lower luminosity ratios when L < 1012 L [NII] Grating [NII] SAFIRE [CII] SAFIRE SOFIA’s Regime [CII] Grating HLIRGS ULIRGS Thick lines denote unique, or nearly unique sensitivity Milky Way Ground based windows SOFIA-SAFIRE FPI or Grating High z Lines • SOFIA/SAFIRE is uniquely positioned for [CII] and [NII] studies in the critical redshift range 0 < z < 1 Blain et al 2002

14. Torus of AGN: XDRs • Dust continuum studies 30 to 60 m • Torus very warm (1000 K), and very dense(~ 107 cm-3)  strong neutral line emission (CO, [OI], H2O; Krolik & Lepp,1989) • Typical source @ 100 Mpc: FJ=17-16 ~ 6  10-18 W-m-2 • High J CO lines are clear signatures and primary coolants of the confining torus – and are very sensitive to the physical conditions of the torus • SOFIA Advantage: CO SED from J ~ 7-6 to J > 58 (48 m)! Artist’s conception of the doughnut shaped torus that confines the emission from an active nucleus (Credit ESA).

15. FORCAST 38 m beam KIWC/KAO Latvakoski et al. 1999 Galactic Center: Circumnuclear Disk • Continuum: FORCAST, HAWC unprecedented  spatial resolution • Dust mass in the ring • Spectrum of density fluctuations • Confinement in strong shear environment– gravity or magnetic fields? • Temperature structure and heating models – young cluster within the disk • Dynamics and excitation with SOFIA Spectrometers • Radial motions?  Signatures of dynamical instabilities (infall?) in the velocity field? • Gas T – chemistry and grain composition (T ~ 200 K in ring)? • What is the local "turbulent" velocity dispersion in CND clumps – evidence for  MHD waves?

16. Galactic Center • Magnetic field using HAWC-polarimeter (not first-light, but possibly not far behind) • The 7" beam (@ 60 ) would provide the best measure yet of the GC magnetic field strength using the Chandrasekhar-Fermi method • The magnetic field direction in the warmest clouds (including the CND) would be determined from the orientation of the polarized E-vectors. Mapping speed will be an issue here!

17. Near Future Plans • Gather up and distribute previous White papers to team (Vacca) • Compile and distribute current instrument capabilities, and estimates for second generation capabilities and compare with Herschel capabilities (Stacey – see Tielens and Casey draft…) • Assign key people to investigate science topics (Team) • Report and debate findings on telecons • Put together document