DUST AND MOLECULES IN SPIRAL GALAXIES as seen with the JCMT

Download DUST AND MOLECULES  IN SPIRAL GALAXIES as seen with the JCMT

Post on 09-Jan-2016

17 views

Category:

Documents

2 download

Embed Size (px)

DESCRIPTION

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 - PowerPoint PPT Presentation

TRANSCRIPT

<ul><li><p>DUST AND MOLECULES IN SPIRAL GALAXIES</p><p>as seen with the JCMTF.P. Israel, Sterrewacht Leiden</p></li><li><p>ATOMS and MOLECULES ... </p></li><li><p>... AND DUST SCUBA 850 mu</p></li><li><p>M51 Line and Continuum</p></li><li><p>M51 J=3-2 COdepleted in center, enhanced in arms</p></li><li><p>ISM in Spiral GalaxiesAtomic gas avoids centerMolecular gas often concentrated in centerDust emission follows total gasMetallicity &amp; excitation gradientsCenter: exclusively molecularInner disk: molecules dominantOuter disk: atoms dominant</p></li><li><p>Nuclear CO concentrationsdisk, torus or spiral?</p></li><li><p>12CO degeneracy resolved by 13co</p></li><li><p>Molecules in galaxy centersConcentrated within R = 0.5 kpcHigh contrast with disk COCO pollutes broadband continuum!Physical parameters only from several line transitions!At least two components:Lukewarm and denseHot and tenuousHot and tenuous gas &gt;50% of mass</p></li><li><p>Dust in galaxy centers</p><p>heating/cooling depends on:dust grain composition dust grain size (distribution)Radiation, shocks, turbulence Size distribution and other properties affected radiatively and dynamically active circumnuclear environment</p></li><li><p>The AGN in CENA </p></li><li><p> M83</p></li><li><p> NGC 6946, NGC 891 1</p></li><li><p>Origin of Subm/FIR emission: NGC 6822 Israel, Bontekoe &amp; Kester, 1996IRAS 60 microns</p><p>I</p></li><li><p>Dust-to-gas ratiosDependent on metallicity, but how ?log [O]/[H] = log Mdust / Mgas + cst</p><p>Issa et al. 1990 = 0.85Schmidt &amp; Boller 1993 = 0.63 Lisenfeld &amp; Ferrara 1998 = 0.52Dwek 1998 (model) = 0.77</p></li><li><p>Interpretation of SEDs</p><p>SED reflects:Big Grains 5-250 nm (MRN, thermal)Very Small Grains (nonthermal)Polycyclic Aromatic Hydrocarbons (PAHs)at various temperatureswith potentially varying size distributions</p></li><li><p>NGC 1569: ISO &amp; SCUBA </p></li><li><p>Cold dust? Lisenfeld et al. 2002, 2005 </p></li><li><p>Same observations, different views</p><p>Galliano et al. 2003dust cold 5-7 Kmost dust in small clumpsgas/dust ratio 320-680(740-1600)Lisenfeld et al. 2002/2005dust warm 35 K processed dust VSG enhanced 7-12 timesgas/dust ratio 1500-2900</p></li><li><p>Evidence for dust processing Spitzer: PAHs depleted in BCDGsweak relation radiation field hardness strong relation energy density Wu et al. 2006, Rosenberg et al 2006, Higdon et al 2006IRAS: PAH depletion sequence f25 / f12: Im 4.5 Sm 2.9 Sc 1.8 Melisse &amp; Israel 1994a, b ANS-UV: behaviour 2175A bumps </p></li><li><p>H2 from FIR or submmindependent from CO measurementsFIR or subm maps tracing dust column densitiesFlux ratios tracing dust temperaturesHI maps tracing atomic gas Assumption dust-to-gas ratio proportional to metallicity (!)</p></li><li><p>X-factor as function of metallicityFilled symbols: large beamOpen symbols: resolved</p><p>log X = - log [O]/[H] + c = -2.3 (+/-0.3) Israel 1997, 2000</p></li><li><p>Molecular gas in galaxy centers</p><p>(Much) less H2 than expected from CO strengthYet molecular gas is &gt;90% of the total gas massOn same curve as metal-poor galaxies?</p></li><li><p>What next?JCMT Legacy Survey Physical Processes in Galaxies in the Local Universe</p><p>299 galaxies randomly selected from an HI-flux-limited sample, plus 32 remaining SINGS galaxies, using HARP-B and SCUBA2 (2007-2009)</p><p>Christine Wilson (Canada)Stephen Serjeant (UK)Frank Israel (NL)(coordinators) and many others</p></li><li><p>JCMT LEGACY SURVEY Physical properties of dust</p><p> Molecular gas and gas-to-dust ratios</p><p> Effects of galaxy morphology Low-metallicity Cluster environment Haloes, superwinds, and AGN</p><p> Luminosity and dust mass functions of galaxies</p></li></ul>

Recommended

View more >