Theme IV: Nearby Galaxies Theme IV: Nearby Galaxies and the Galactic Centerand the Galactic Center

G.J. Stacey

Cornell University

Team MembersTeam 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 MembersTeam 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 MembersTeam 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

ActivitiesActivities

Team assembled in April/MayFirst Telecon in late May

Discussion of scope of our assignment – where do we fit in?

Discussion of science topicsDiscussion of timelinesTelecons scheduled for Wednesdays at noon

eastern time

Where do we fit in?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 CenterSection on HAWC observations of the distant

UniverseSection on nearby Galaxies

How do we fit in?

Goals/ScheduleGoals/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 GalaxiesExample: Nearby Galaxies

Stellar evolution

Diffuse interstellar gas

Dense interstellarclouds

Star formation

Windsstellar explosions

Stellar remnants

Primordial gas

Cooling, contractionchemistry

Contraction,gravitational instability

H, He, C+, O

H2, He, CO

Interstellar Gas and Interstellar Gas and the Stellar Life Cyclethe Stellar Life Cycle

Example: Nearby Spiral GalaxiesExample: 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 StrengthsSOFIA Strengths Mapping capabilities

Large field of view for cameras (e.g. FORCAST 33’ FOV, SAFIRE FPI ~ 2.75.3’ 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 StrengthsSOFIA 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 GalaxiesEvolution 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 SOFIA-SAFIRE FPI or Grating High z LinesLines

SOFIA/SAFIRE is uniquely positioned for [CII] and [NII] studies in the critical redshift range 0 < z < 1

1.E+10

1.E+11

1.E+12

1.E+13

1.E+14

1.E+15

0 0.5 1 1.5 2 2.5 3

Redshift (z)

Far-IR Luminosity

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 < 1012 L

Blain et al 2002

SOFIA’s Regime

Ground based windows

Torus of AGN: XDRsTorus 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).

Galactic Center: Circumnuclear DiskGalactic 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. 1999

FORCAST 38 m beam

Galactic CenterGalactic 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 PlansNear 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