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Extragalactic Star Formation activity

Extragalactic Star Formation activity. Eagle Nebulae. NGC 253. Antennae. Estelle Bayet. Collaborators : S. Viti (UCL-UK), D.A.Williams (UCL-UK), J. Martin-Pintado (CSIC-Spain), S. Martin (ESO-Chile), R. Aladro (IRAM-Spain), Z. Awad (UCL-UK),…. I II III IV. Outline :

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Extragalactic Star Formation activity

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  1. Extragalactic Star Formation activity Eagle Nebulae NGC 253 Antennae Estelle Bayet Collaborators : S. Viti (UCL-UK), D.A.Williams (UCL-UK), J. Martin-Pintado (CSIC-Spain), S. Martin (ESO-Chile), R. Aladro (IRAM-Spain), Z. Awad (UCL-UK),…

  2. I II III IV Outline : I. Motivation and context II. Results: II.a. Molecular extended gas (PDR) II.b. Molecular very dense gas III. Molecules useful for inferring SF activity? IV. Conclusions and Perspectives

  3. I II III IV Extragalactic Star Formation activity NGC 253 AGN or SB Molecular gas Star-forming regions Dust grains Ionised gas Winds, outflows or inflows Stars Dark Matter halo Etc… A MESS !!!

  4. I II III IV Assumed Star-forming regions Ionized gas AGN or SB Atomic gas Density increase Molecular gas Star-forming regions Molecular extended gas (PDR) Dust grains Ionised gas Molecular very dense gas Winds, outflows or inflows Stars Dark Matter halo Stars in formation Etc…

  5. I II III IV Assumed Star-forming regions AGN or SB Molecular gas Star-forming regions Dust grains Ionised gas Winds, outflows or inflows Stars Dark Matter halo Etc… ``Isolated” or in filamentary structure

  6. I II III IV Assumed Star-forming regions AGN or SB Molecular gas Star-forming regions Dust grains Ionised gas Winds, outflows or inflows Stars Dark Matter halo Etc… Stars already formed, UV & FUV sources

  7. I II III IV Assumed Star-forming regions AGN or SB Molecular gas Star-forming regions Dust grains Ionised gas Winds, outflows or inflows Stars Dark Matter halo Etc… Starburst (SB)  NUCLEUS

  8. I II III IV Assumed Star-forming regions AGN or SB Molecular gas Star-forming regions Dust grains Ionised gas Winds, outflows or inflows Stars Dark Matter halo Etc… Active Galactic Nucleus (AGN)  NUCLEUS

  9. I II III IV Assumed Star-forming regions AGN or SB Molecular gas Star-forming regions Dust grains Ionised gas Winds, outflows or inflows Stars Dark Matter halo Etc… SB + AGN  NUCLEUS

  10. I II III IV Interest of Extragalactic studies ? • Various chemical and physical conditions investigated !!! •  SFR from 10 to 100 M0/yrs

  11. I II III APM 08279 z ~ 4 Henize 2-10 NGC 253 Antennae IC 10 IC 342 M 83 NGC 6946

  12. I II III IV Interest of Extragalactic studies ? • Various chemical and physical conditions investigated !!! •  SFR from 10 to 100 M0/yrs • Main issue: spatial resolution !!!

  13. I II III IV I. Context and Key questions IRAM Plateau de Bure Interferometer (IRAM-PdB) Caltech Submillimeter Observatory (CSO) ~ 5” = 16 pc ~ 22” = 71 pc IC 10: Composite image in RGB (NOAO)

  14. I II III IV Interest of Extragalactic studies ? • Various chemical and physical conditions investigated !!! •  SFR from 10 to 100 M0/yrs • Main issue: spatial resolution !!! Limitation: Gas dense and less dense mixed + Dust and gas mixed  AVERAGE properties derived but CHEMISTRY CAN HELP !! ALMA

  15. III III IV II. Results Spatial scales !!! Stars already formed, UV & FUV sources Ionized gas Atomic gas Density increase Molecular extended gas (PDR) Molecular very dense gas Young stars in formation Schematic representation of star-forming region

  16. III a III IV II.a. Molecular extended gas (PDR) Spatial scales !!! Stars already formed, UV & FUV sources Galactic PDR gas : n(H2) ≤ 104-5 cm-3 Temperature ~ 40-150 K Lifetime > 105 yrs Atomic and molecular chemical abundances Molecular extended gas (PDR) Schematic representation of star-forming region

  17. III a III IV II.a. Molecular extended gas (PDR) NGC 253 He 2-10 Observations: Overlap Bayet et al, 2004, A&A, 427, 45 Bayet et al., 2006, A&A, 460, 467 Caltech Submillimeter Observatory (CSO) NGC 253

  18. III a III IV II.a. Molecular extended gas (PDR) Models  ISM properties PDR (Meudon) model LVG model TK , <σv> and density are uniform Line of sight 0D model Spherical geometry Equation of statistical equilibrium + collision rates Velocity = fo(radius) TK and density uniform Radiation intensity = fo(S;escape probabilities of a photon emitted by the molecular transition) ONE MOLECULE ONLY !!  TB  Amb Level population + uniform throughout the cloud 1D model Steady state Radiative transfer solved (dust and line absorptions) Heating and cooling processes Thermal balance Chemical network  MULTI-MOLECULES !!! Plan-// geometry  Imb

  19. III a III IV II.a. Molecular extended gas (PDR) Results  Observed and predicted SEDs Bayet et al., 2006, A&A, 460, 467 C and CO cooling rates obtained for about 10 nearby galaxies Whatever the galaxy

  20. III a III IV II. PDR-like gas B)Models  ISM properties Bayet et al., 2006, A&A, 460, 467

  21. III b III IV II.b. Molecular very dense gas Spatial scales !!! Stars already formed, UV & FUV sources Ionized gas Atomic gas Density increase Molecular extended gas (PDR) Molecular very dense gas Young stars in formation Schematic representation of star-forming region

  22. III b III IV II.b. Molecular very dense gas Spatial scales !!! Stars already formed, UV & FUV sources Galactic very dense gas : n(H2) ~ 107 cm-3 Temperature > 100 K Lifetime ~ 105 yrs Chemical abundances anomalously high (NH3, H2O, HCOOCH3…) Molecular very dense gas Observations in external galaxies? Not really, HCN not a good tracer… Young stars in formation Models  Predictions Schematic representation of star-forming region

  23. III b III IV II.b. Molecular very dense gas Spatial scales !!! Stars already formed, UV & FUV sources Galactic very dense gas : n(H2) ~ 107 cm-3 Temperature > 100 K Lifetime ~ 105 yrs Chemical abundances anomalously high (NH3, H2O, HCOOCH3…) Molecular very dense gas Observations in external galaxies? Not really, HCN not a good tracer… Young stars in formation Models  Predictions Use of the UCL chemical model to derive the dense gas properties complementary information on the chemical and physical properties of high mass star regions

  24. III b III IV II.b. Molecular very dense gas PHASE 1 : contraction of the cloud until a limit density  star formed Temperature is very cold (10 K) thus molecules are frozen out onto the grains B)Models  Predictions Schematic representation of dense region PHASE 2 : evaporation massive star formed instantaneously T (300 K) Molecules stuck are released in the gas phase since grains are violently heated FORMATION OF THE DENSE GAS CHEMISTRY : tracers identified !! Molecular cloud - PDR Formation of the protostar by itself not included !!! Molecular cloud - PDR

  25. III b III IV II.b. Molecular very dense gas Models  Predictions “quiet” environment = Milky Way standard values used limit of detectability: relative abundance = 10-12 Bayet et al. 2008a, ApJ, 676, 978

  26. III b III IV z = z0 II.b. Molecular very dense gas z = 1/10z0 z = 1/100z0 Models  Predictions z =1/1000 z0 Variations of input parameters: metallicity (z) FUV radiation field Cosmic ray ionisation rate Temperature, … Bayet et al. 2008a, ApJ, 676, 978

  27. III b III IV II.b. Molecular very dense gas Models  Predictions Bayet et al. 2008a, ApJ, 676, 978 Useful for the preparation of future observations with ALMA

  28. III b IIIIV II.b. Molecular very dense gas Observations Purpose : Validation of model predictions  Physical parameters of this dense gas to derive  Comparison with “C, CO” gas properties (see Sect. IV) JCMT Molecule CS : lines critical densities from 105 to 107 cm-3 well known spectroscopically Transitions observed from CS(2-1) to CS(7-6) various galaxies !!! IRAM-30m

  29. III b IIIIV Antennae A)Observations Bayet et al. 2009c, ApJ, 707,126

  30. M 82 PreambleI IIIIIa IV V Weiss et al., 2001, A&A, 365, 571 III. Dense gas A)Observations Bayet et al. 2009c, ApJ, 707, 126 Bayet et al. 2008b, ApJL, 685, 33 Bayet et al. 2009c, ApJ, 707, 126

  31. III b IIIIV II.b. Molecular very dense gas Observations  ISM properties Bayet et al. 2009b, ApJ, 707, 126

  32. I II bIII IV III. Molecules useful for inferring SF activity? Chemical model: very dense gas UCL_PDR model: PDR-like gas Schematic representation of hot core Molecular cloud - PDR Viti & Williams, 1999, MNRAS, 305, 705 Viti et al., 2001, A&A, 370, 1071 Bell et al., 2006, MNRAS, 371, 1875 Bell et al., 2007, MNRAS, 378, 983 Molecular cloud - PDR

  33. I II bIII IV III. Molecules useful for inferring SF activity? Chemical model: very dense gas UCL_PDR model: PDR-like gas z = z0 z = z0 z = 1/10z0 z = ½ z0 z = ¼ z0 z = 1/100z0 z = 1/10 z0 z =1/1000 z0 z =1/100 z0 Bayet et al. 2009a, ApJ, 696, 1466 Bayet et al. 2008a, ApJ, 676, 978

  34. I II bIII IV III. Molecules useful for inferring SF activity? UCL_PDR model: PDR-like gas Chemical model: very dense gas Bayet et al. 2009a, ApJ, 696, 1466 Bayet et al. 2008a, ApJ, 676, 978 Observational campaign to perform  able to disentangle nuclear activity? New tools for ALMA & Herchel ?

  35. I II b III IV IV. Conclusions and Perspectives II.a.Molecular extended gas (PDR) : UNTIL NOW :  Observations : C and CO lines at high frequencies never obtained before(nearby sources)  SED : cooling rates determined for the typical PDR gas as traced by C and CO lines  Models : physical properties of PDR gas determined NEXT ? : Interferometric data  GMCs (obs + models) II.b. Molecular very dense gas : UNTIL NOW :  Models: tracers of dense gas in various types of galaxies identified + study of their abundance variations with physical conditions  Observations : CS never obtained before + lower limit for N(CS) and TK of dense star-forming gas in various galaxies

  36. I II b III IV IV. Conclusions and Perspectives NEXT ?: - Models: use RT, LVG models for deriving the ISM physical properties of this dense gas - Observations : observe not only CS ! Maps? III. Molecules useful for inferring SF activity? UNTIL NOW :  identified various differences in tracers for both gas in various types of galaxies (nuclear activity) NEXT ? :- Confirm these differences observationally speaking - Increase the comparison adding real XDR model predictions IV. Perspective works : 1) Comparison with the dust emission : complementary information on conditions

  37. PreambleI II III IV V IRAM Plateau de Bure Interferometer (IRAM-PdB) V. Conclusions and perspective Bayet et al. (in prep) Spatial resolution of 6.01’’ x 4.86’’ at 115 GHz : IC 10 Superimposition of the 12C0(1-0) emission (black contours : 1-15 Jy/beam.kms-1) with the λ~7 μm emission The Antennae Galaxies - CO(1-0) from Wilson et al.(200) with OVRO - Other from Bayet et al. (in prep) with Spitzer Bayet et al. (in prep)

  38. I II b III IV IV. Conclusions and Perspectives Deuterated chemistry in external galaxies Density (cm-3) 105 106 107 105 106 107 105 106 107 105 106 107 105 106 107 IN PROGRESS !!! See Poster of Zainab Awad

  39. I II b III IV IV. Conclusions and Perspectives Herschel ALMA Thank you !

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