1 / 27

DUST AND MOLECULES IN SPIRAL GALAXIES as seen with the JCMT

F.P. Israel, Sterrewacht Leiden. DUST AND MOLECULES IN SPIRAL GALAXIES as seen with the JCMT. ATOMS and MOLECULES. ... AND DUST. SCUBA 850 mu. M51 Line and Continuum. M51 J=3-2 CO depleted in center, enhanced in arms. ISM in Spiral Galaxies. Atomic gas avoids center

imelda
Download Presentation

DUST AND MOLECULES IN SPIRAL GALAXIES as seen with the JCMT

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. F.P. Israel, Sterrewacht Leiden DUSTAND MOLECULES IN SPIRAL GALAXIESas seen with the JCMT

  2. ATOMS and MOLECULES ...

  3. ... AND DUST • SCUBA 850 mu

  4. M51 Line and Continuum

  5. M51 J=3-2 COdepleted in center, enhanced in arms

  6. ISMinSpiralGalaxies • Atomic gas avoids center • Molecular gas often concentrated in center • Dust emission follows total gas • Metallicity & excitation gradients • Center: exclusively molecular • Inner disk: molecules dominant • Outer disk: atoms dominant

  7. Nuclear CO concentrationsdisk, torus or spiral?

  8. 12CO degeneracyresolved by 13co

  9. Molecules in galaxy centers • Concentrated within R = 0.5 kpc • High contrast with disk CO • CO pollutes broadband continuum! • Physical parameters only from several line transitions! • At least two components: • Lukewarm and dense • Hot and tenuous • Hot and tenuous gas >50% of mass

  10. Dust in galaxy centers Size distribution and other properties affected radiatively and dynamically active circumnuclear environment heating/cooling depends on: • dust grain composition • dust grain size (distribution) • Radiation, shocks, turbulence

  11. The AGN in CENA

  12. M83

  13. NGC 6946, NGC 891 1

  14. IRAS 60 microns I OriginofSubm/FIRemission: NGC6822 Israel, Bontekoe & Kester, 1996

  15. Dust-to-gasratios Dependent on metallicity, but how ? log [O]/[H] = α logMdust / Mgas+ cst Issa et al. 1990 α = 0.85 Schmidt & Boller 1993 α = 0.63 Lisenfeld & Ferrara 1998 α = 0.52 Dwek 1998 (model) α = 0.77

  16. Interpretation of SEDs SED reflects: Big Grains 5-250 nm (MRN, thermal) Very Small Grains (nonthermal) Polycyclic Aromatic Hydrocarbons (PAHs) at various temperatures with potentially varying sizedistributions

  17. NGC 1569: ISO & SCUBA

  18. Colddust? Lisenfeld et al. 2002, 2005

  19. Lisenfeld et al. 2002/2005 dust warm 35 K processed dust VSG enhanced 7-12 times gas/dust ratio 1500-2900 Sameobservations, differentviews Galliano et al. 2003 dust cold 5-7 K most dust in small clumps gas/dust ratio 320-680 (740-1600)

  20. Evidence for dust processing Spitzer: PAHsdepletedinBCDGs • weak relation radiation field hardness • strong relation energy density Wu et al. 2006, Rosenberg et al 2006, Higdon et al 2006 IRAS: PAH depletion sequence f25 / f12: Im 4.5 Sm 2.9 Sc 1.8 Melisse & Israel 1994a, b ANS-UV: behaviour 2175A bumps

  21. H2 from FIR or submmindependent from CO measurements • FIR or subm maps tracing dust column densities • Flux ratios tracing dust temperatures • HI maps tracing atomic gas • Assumption dust-to-gas ratio proportional to metallicity (!)

  22. X-factor as function of metallicity Filled symbols: large beam Open symbols: resolved log X = -α log [O]/[H] + c α = -2.3 (+/-0.3) Israel 1997, 2000

  23. Moleculargasingalaxy centers • (Much) less H2 than expected from CO strength • Yet molecular gas is >90% of the total gas mass • On same curve as metal-poor galaxies?

  24. JCMT Legacy Survey Physical Processes in Galaxies in the Local Universe 299 galaxies randomly selected from an HI-flux-limited sample, plus 32 remaining SINGS galaxies, using HARP-B and SCUBA2 (2007-2009) Christine Wilson (Canada) Stephen Serjeant (UK) Frank Israel (NL) (coordinators) and many others What next?

  25. Physical properties of dust Molecular gas and gas-to-dust ratios Effects of galaxy morphology Low-metallicity Cluster environment Haloes, superwinds, and AGN Luminosity and dust mass functions of galaxies JCMT LEGACY SURVEY

More Related