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Henize 2-10

IC 10. NGC 253. Henize 2-10. COMPARISON OF GAS AND DUST COOLING RATES IN NEARBY GALAXIES E.Bayet : LRA-LERMA-ENS (Paris). Antennae. IC 342. M 83. NGC 6946. INTRODUCTION :. OBJECTS : warm and dense molecular clouds in the nuclei of 20 nearby galaxies with

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Henize 2-10

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  1. IC 10 NGC 253 Henize 2-10 COMPARISON OF GAS AND DUST COOLING RATES IN NEARBY GALAXIES E.Bayet: LRA-LERMA-ENS (Paris) Antennae IC 342 M 83 NGC 6946

  2. INTRODUCTION : OBJECTS: warm and dense molecular clouds in the nuclei of 20 nearby galaxies with different morphological types (D < 10 Mpc) GOALS : 1) describe the physical properties of these objects  localize the GMCs in these nuclei  correlations morphological types - cooling rates ?  prediction of emission lines for more distant objects 2) understand the links existing between dust and gas cooling rates HOW : Observations of C and CO lines in mm-submm windows (υ=200-850GHz) with CSO (Hawaii, USA) and IRAM-PdB (FRANCE) for the first time  C(3P2-3P1)(υ=809GHz)  high-J CO lines observed : 12CO(6-5), (7-6) (υ=691GHz, 806GHz) LVG (radiative transfer calculations) and PDR (photodissociation regions- thermal balance) models to derive the physical properties targets for ALMA and Herschel

  3. GALAXIES SAMPLE : Properties : - accessibles from the northern hemisphere - bright in the low-J CO lines, e.g., 12CO(1-0) and 12CO(2-1) - ~20 nearby galaxies with different morphological types: normal spiral galaxies: IC 342, M 51, NGC 6946 irregular star forming galaxies: Henize 2-10 , IC 10 starburst galaxies: M 82, M 83, NGC 253 interacting galaxies: NGC 6090, IRAS 10565+2448, the Antennae ULIRGs: Markarian 231, Arp 220 LINER: NGC 4736, NGC 3079 … IC 342, NGC 6946 Henize 2-10 M 83, NGC 253 the Antennae

  4. OBSERVED LINES : Study of the variation of C over CO density ratio N(C)/ N(CO) in the molecular cloud CO = good tracer of H2 molecular masses C linked with PDRs (mostly in the first layers) Cloudsare ruled by: heating - photoelectric effects on grains - collisionnal deexcitation of H2 cooling(condensation of clouds = star formation) - neutral layer (Av < 5): CII, OI - molecular layer (Av > 5) : CO & C CO lines refer to transitions between two rotationnal levels C lines refer to transitions between two electronical levels From Hollenbach & Tielens (1999)

  5. MODELS : LVG ( Large Velocity Gradient ) : radiative transfer calculations with one standard spherical component + Tk and gas density considered as constant 4 input parameters : N(CO)/FWHM , n(H2), Tk and abundance ratio 12CO/13CO (13CO used for discriminating solutions) PDR or «photodissociation regions» : 2 input parameters : radiation field and n(H) + gaseous phase abundances, etc… n(H2), Tk N(CO)/FWHM, 12CO/13CO radiation field Intensities of each CO lines are computed up to12CO(15-14) and we computed intensities of C lines C(3P1-3P0) & C(3P2-3P1) Comparison with observations Physical properties of the ISM derived !! From Hollenbach & Tielens (1999)

  6. RESULTS : example (IC 342) of CO cooling curve Observations of the 13CO(6-5), 12CO(8-7) and up will be very useful to discriminate models solutions ALMA & Herschel !! 2 LVG models needed to reproduce cold and warm molecular gas

  7. CO cooling curves : • He 2-10, M 83 & Cloverleaf QSO : •  peak position 12CO(7-6)and up • IC 10, NGC 253, NGC 4038, NGC 6946 • & Overlap : •  peak position 12CO(6-5) • IC 342 and Center of Milky Way : •  peak position 12CO(5-4) and below • CO(5-4) to CO(7-6) = major • coolants • C(3P2-3P1) = major coolant • CO cooling rate > C cooling • rate • Similarities in the CO • cooling curves mean • similarities in the physical • properties, morphological • types Grey full points are derived from PDR models

  8. Comparison between differents tracers : 1) Morphologic (neutral and molecular gas + dust) • Larger dispersion in dust cooling than in radiation field and density  Radiation field (CII / C)  Density (CII / OI) • Contribution of the CII from PDR more important in • NGC 6946 Dust cooling Dust cooling • CO cooling rate • more efficient than • C cooling rate  Cooling efficiency (CO / FIR & C/ FIR) PDR / TOTAL (CII) • IC 10 clearly • differs from others Dust cooling Heating efficiency

  9. Comparison between differents tracers : 1) Morphologic (bis) (neutral and molecular gas + dust) * CO(1-0) known as tracer of star formation * Total CO cooling rates computed from 1-0 to 15-14 lines (PDR) also good tracer Dust cooling

  10. Comparison between differents tracers : 2) Coolants (neutral and molecular gas + dust) • Correlations • between • CII, C and CO • cooling rates • CII cooling rate • > OI cooling • rate • Starburst galaxies • (NGC 253, M 83) • have the highest • CII, OI, C & CO • cooling rates and • highest FIR flux • Merger and irregular galaxies have the lowest rates

  11. PERSPECTIVES : MERCI ! • Finish the analysis of these figures and quantify precisely the links existing between • morphological type of nuclei & lines which contribute the most to the CO and • C cooling rates • different coolant species (relation between neutral, molecular gas and dust) • cooling and heating processes in the GMCs • Complete these results with the other galaxies from our sample: LVG and PDR models should be applied (already published paper in A&A: The submillimeter C and CO lines in Henize 2-10 and NGC 253 and paper in preparation for the other sources) • Other works in progress: - Localize the GMCs in IC 10 nucleus from high resolution • IRAM-Plateau De Bure observations and compare CO with ISO data (LW2 et LW3 at • 7 and 15 µm) • - Collaboration at the Leiden Observatory (F. Israel) • concerning models: plan to use a combined XDR-PDR models in development • My PhD work shall be included in the future large programs performed • by ALMA, the Herschel satellite with the HIFI, PACSand SPIRE instruments and the • Spitzer Space Satellite with the IRAC camera and the IRS spectrometer.

  12. OBSERVED LINES : CO & C : several lines which emit: 12CO(1-0), 12CO(2-1), 12CO(3-2), 12CO(4-3)… 13CO(1-0), 13CO(2-1)... C(3P1-3P0), C(3P2-3P1) CO lines : transitions between two rotationnal levels ex: CO(3-2)  transition from level J = 3 to J = 2 C lines : transitions between two electronical levels ex: C(3P1-3P0)  transitions from level 3P1 to 3P0 CII & OI emission lines from literature (ISO, KAO…) Observations and study ofhigh-J CO lines (12CO(6-5) et (7-6)) = signature of warm and dense molecular gas (n(H2) ~104 cm-3, Tk ~50-100 K) 1-0 Hollenbach & Tielens (1999)

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