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

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

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

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

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

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?

Goals/Schedule  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 June 18 July 16 August 13 October 1

Example: Nearby Galaxies Stellar evolution Diffuse interstellar gas Dense interstellar clouds Star formation Winds stellar explosions Stellar remnants Primordial gas Cooling, contraction chemistry Contraction, gravitational instability H, He, C +, O H 2, He, CO Interstellar Gas and the Stellar Life Cycle

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 SAFIRE FOV Beam at [OI]

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

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

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)

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 HLIRGS ULIRGS Milky Way [NII] Grating [NII] SAFIRE [CII] SAFIRE [CII] Grating Thick lines denote unique, or nearly unique sensitivity 5  in 2 hours – ULIRG line to continuum ratios: Adjusted to lower luminosity ratios when L < L  Blain et al 2002 SOFIA’s Regime Ground based windows

Torus of AGN: XDRs  Dust continuum studies 30 to 60  m  Torus very warm (1000 K), and very dense (~ 10 7 cm -3 )  strong neutral line emission (CO, [OI], H 2 O; Krolik & Lepp,1989)  Typical 100 Mpc: F J=17-16 ~ 6  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).

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? KIWC/KAO Latvakoski et al FORCAST 38  m beam

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!

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