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Excitation Mechanisms: The Irradiated and Stirred ISM Marco Spaans (Groningen) Rowin Meijerink (Leiden), Frank Israel (Leiden), Edo Loenen (Leiden), Willem.

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Presentation on theme: "Excitation Mechanisms: The Irradiated and Stirred ISM Marco Spaans (Groningen) Rowin Meijerink (Leiden), Frank Israel (Leiden), Edo Loenen (Leiden), Willem."— Presentation transcript:

1 Excitation Mechanisms: The Irradiated and Stirred ISM Marco Spaans (Groningen) Rowin Meijerink (Leiden), Frank Israel (Leiden), Edo Loenen (Leiden), Willem Baan (ASTRON), Juan-Pablo Perez-Beaupuits (Groningen) Dominik Schleicher (Leiden/ESO), Ralf Klessen (Heidelberg), Padelis Papadopoulos (Bonn), Paul van der Werf (Leiden) Rowin Meijerink (Leiden), Frank Israel (Leiden), Edo Loenen (Leiden), Willem Baan (ASTRON), Juan-Pablo Perez-Beaupuits (Groningen) Dominik Schleicher (Leiden/ESO), Ralf Klessen (Heidelberg), Padelis Papadopoulos (Bonn), Paul van der Werf (Leiden)

2 n Concentrate on irradiated turbulent gas in star-forming regions and close to AGN n PDRs (UV/SB) n XDRs (X-ray/AGN) n MDRs (turbulence/flows) n CRDRs (CRs/SNe) n Photon excitation (pumping/dust)

3 Energetics G 0 = 1.6x10 -3 erg cm -2 s -1 is the Habing flux over eV G 0 = 1.6x10 -3 erg cm -2 s -1 is the Habing flux over eV Orion Bar has 10 5 G 0 Orion Bar has 10 5 G 0 F X = 84 L 44 r 2 -2 erg cm -2 s -1 F X = 84 L 44 r 2 -2 erg cm -2 s -1 is the X-ray flux over keV with a power law E -0.9 is the X-ray flux over keV with a power law E -0.9 Think of Seyfert nucleus at 100 pc or TTauri star with erg/s at 20 AU Think of Seyfert nucleus at 100 pc or TTauri star with erg/s at 20 AU

4 PDRs: 6 < E < 13.6 eV n Heating: Photo-electric emission from grains and cosmic rays n Cooling: Fine-structure lines like [OI] 63, 145; [CII] 158 μm and emission by H 2, CO, H 2 O n 10 eV photon penetrates 0.5 mag of dust n Heating efficiency ~ 0.1 – 1.0 %

5 n Orion Bar (van der Werf 1993)

6 XDRs: E > 1 keV n Heating: X-ray photo-ionization --> fast electrons - Coulomb heating H and H 2 vib excitation - UV n Cooling: [FeII] 1.26, 1.64; [OI] 63; [CII] 158; [SiII] 35 μm; thermal H 2 vib; gas-dust n 1 keV photon penetrates cm -2 of N H n Heating efficiency ~ 10 – 50 %

7 30 Doradus (Brandl et al. 2007)

8 Maloney et al. (1996)

9 n PDR (left) with n=10 5 cm -3 and G= n XDR with n=10 5 cm -3 and F X = 5.1 erg s -1 cm -3 n Note N H dependence H 2, C +, C, CO, OH, H 2 O: FIR lines of species trace different regions

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12 Fine-structure lines (Kaufman et al. 1999; Meijerink et al. 2007

13 J=16-15 at 1841 GHz (0.16 mm) redshifted into ALMA window ( Spaans & Meijerink 2008)

14 Mrk 231 SPIRE (see Loenen presentation; van der Werf et al. 2010) CO SLED has not yet turned down at J=13-12

15 A comment on AGN: Relative Size PDR/XDR n 10 7 M ๏ BH at 3% Eddington for G 0 =100 and keV powerlaw of slope -1 (with 10% L bol ; Schleicher et al ) n Check out poster Pérez-Beaupuits!

16 Metallicity and Multi-Phase ISM : n Lower metallicity yields smaller molecular clouds n Atomic cooling dominates by mass n X-factor: Mihos et al. (1999) Bolatto et al. (1999), Roellig et al. (2006)

17 Multi-Phase Medium; atomic vs molecular (Wolfire et al. 2003; Spaans & Norman 1997)

18 MDRs: how about kinetics? n Mechanically Dominated Regions n Turbulent dissipation heats the gas, which leads to IR emission n UV only heats cloud surface n Cosmic rays also heat deep inside cloud, but strongly affect HCO + n E.g., at T>100K: HNC + H  HCN + H

19 Sources of Turbulence n YSOs n SNe n Sloshing motions (accretion) n If 1-10% efficiency through a turbulent cascade -> mechanical heating competes with normal CR heating for SF rates of 10 – 100 M o /yr

20 M82, shock tracer SiO GHz radio (García-Burillo et al. 2001, IRAM PdB)

21 g n E.g., P cygni profiles in Arp220: 100 km/s outflow ( 100 pc scale; Sakamoto et al )

22 Mrk 231, SPIRE, outflow in OH upto 10 3 km/s (Fischer et al. 2010)

23  Temperature increases  E.g., HNC, HCN, HCO + affected normal mechanical Turbulent dissipation causes changes in high density tracers (Loenen et al. 2008)

24 For some ULIRGs, dense gas tracers that correlate with IR may trace more SN than UV exposure

25 n How about CRs? n PDR model with CR rate = 5x s -1 ; so SN rate for ~100 M 0 /yr n Note small changes in C, OH and H 2 O

26 CRs can dominate gas heating for SFR > 100 Mo/yr; think of Arp220 and IMF through M Jeans (Papadopoulos 2010)

27 CRs ≠ X-rays; only very high CR rates boost OH + and H 2 O + (fine-structure lines little affected by CRs)

28 HNC (HCN) rotational lines pumped by mid-IR photons at 21.5 (14) μ m that are absorbed by the degenerate bending mode (1st vibrational level) and decay via the P branch (Aalto et al. 2007). A=5.2 (1.7) s -1 for HNC (HCN); requires T IR ~50 K ( τ >1) and n

29 Mrk 231; SPIRE, IR pumping of water lines by dust emission (Gonzalez-Alfonso 2010)

30 Summary n PDRs, XDRs, MDRs and CRDRs are likely to be present simultaneously, but are also distinguishable n For the future, ALMA will be crucial to provide spatial information to separate the XDR and thus constrain properties of accreting supermassive black holes and feedback effects


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