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Radiative and mechanical feedback in the molecular gas in (U)LIRGs

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  1. Radiative and mechanical feedback in the molecular gas in (U)LIRGs London September 16, 2011

  2. Credits Kate Isaak (ESTEC) Padelis Papadopoulos (MPI für Radioastronomie) Marco Spaans (Kapteyn Astronomical Institute) Eduardo González-Alfonso (Henares) Rowin Meijerink (Leiden Observatory) Edo Loenen (Leiden Observatory) – talk after tea Alicia Berciano Alba (Leiden Observatory/ASTRON) – next talk Axel Weiß (MPI für Radioastronomie) + the HerCULES team Feedback in (U)LIRGs

  3. Outline • Introducing HerCULES • H2O emission in (U)LIRGs • Radiation pressure dominated disks in (U)LIRGs Feedback in (U)LIRGs

  4. Introducing HerCULES Herschel Comprehensive (U)LIRG Emission Survey Open Time Key Program on the Herschel satellite Feedback in (U)LIRGs

  5. HerCULES in a nutshell • HerCULES measures uniformly and statistically the neutral gas cooling lines in a flux-limited sample of 29 (U)LIRGs. • Sample: • all IRAS RBGS ULIRGs with S60 > 12.19 Jy (6 sources) • all IRAS RBGS LIRGs with S60 > 16.8 Jy (23 sources) • Observations: • SPIRE/FTS full high-resolution scans: 200 to 670 m at R ≈ 600, covering CO 4—3 to 13—12 and [CI] + any other bright lines • PACS line scans of [CII] and both [OI] lines • All targets observed to same (expected) S/N • Extended sources observed at several positions Feedback in (U)LIRGs

  6. Who is HerCULES? Jesus Martín-Pintado (Madrid) Joe Mazzarella (IPAC) RowinMeijerink (Leiden) David Naylor (Lethbridge) Padelis Papadopoulos (Bonn) Dave Sanders (U Hawaii) Giorgio Savini (Cardiff/UCL) Howard Smith (CfA) Marco Spaans (Groningen) Luigi Spinoglio (Rome) Gordon Stacey (Cornell) Sylvain Veilleux (U Maryland) Cat Vlahakis (Leiden/Santiago) Fabian Walter (MPIA) Axel Weiß (MPIfR) Martina Wiedner (Paris) Manolis Xilouris (Athens) Paul van der Werf (Leiden; PI) Susanne Aalto (Onsala) Lee Armus (Spitzer SC) Vassilis Charmandaris (Crete) Kalliopi Dasyra (CEA) Aaron Evans (Charlottesville) Jackie Fischer (NRL) Yu Gao (Purple Mountain) Eduardo González-Alfonso (Henares) Thomas Greve (Copenhagen) Rolf Güsten (MPIfR) Andy Harris (U Maryland) Chris Henkel (MPIfR) Kate Isaak (ESA) Frank Israel (Leiden) Carsten Kramer (IRAM) Edo Loenen (Leiden) Steve Lord (NASA Herschel SC) Feedback in (U)LIRGs

  7. HerCULES sample Feedback in (U)LIRGs

  8. Outline • Introducing HerCULES • H2O emission in (U)LIRGs • Radiation pressure dominated disks in (U)LIRGs Feedback in (U)LIRGs

  9. Water in molecular clouds • H2O ice abundant in molecular clouds • Can be released into the gas phase by UV photons, X-rays, cosmic rays, shocks,... • Can be formed directly in the gas phase in warm molecular gas • Abundant, many strong transitions  expected to be major coolant of warm, dense molecular gas Herschel image of (part of) the Rosetta Molecular Cloud Feedback in (U)LIRGs

  10. Low-z H2O: M82 vs. Mrk231 M82 Mrk231 • At z=0.042, one of the closest QSOs (DL=192 Mpc) • With LIR = 41012 L , the most luminous ULIRG in the IRAS Revised bright Galaxy Sample • At D = 3.9 Mpc, one of the closest starburst galaxies • With LIR = 31010 L , a very moderate starburst Feedback in (U)LIRGs

  11. H2O lines in M82 (Weiß et al., 2010) (Panuzzo et al., 2010) • Faint lines, complex profiles • Only lines of low excitation Feedback in (U)LIRGs

  12. Mrk231:strong H2O lines, high excitation (Van der Werf et al., González-Alfonso et al., 2010) Feedback in (U)LIRGs

  13. Mrk231: details • New detections: • H2O ground state • H218O (2 lines) • H3O+ (3 lines) • NH3 • NH2? • several unassigned lines Feedback in (U)LIRGs

  14. H2O lines in Mrk231 • Low lines: pumping by cool component + some collisional excitation • High lines: pumping by warm component • Radiative pumping dominates and reveals an infrared-opaque (100m ~ 1) disk. (González-Alfonso et al., 2010) Feedback in (U)LIRGs

  15. Lessons from H2O (1 + 2) 2) Radiatively H2O lines reveal extended infrared-opaque circumnuclear gas disks. 1) In spite of high luminosities, H2O lines are unimportant for cooling the warm molecular gas. Feedback in (U)LIRGs

  16. Lessons from H2O (3) Radiation pressure from the strong IR radiation field: Since both 100 and Td are high,radiation pressure dominates the gas dynamics in the circumnuclear disk. 3) Conditions in the circumnuclear molecular disk are Eddington-limited. Feedback in (U)LIRGs

  17. Eddington-limited consequences • Eddington-limited conditions predict the LFIR-LHCN relation within factor 2 for standard dust/gas ratio (Andrews & Thompson 2011) • If accreting towards nuclear SMBH, can account for M*/M relation (Thompson et al., 2005) • Radiation pressure can expel nuclear fuel and produce Faber-Jackson relation (Murray et al., 2005) (Andrews & Thompson, 2011) Feedback in (U)LIRGs

  18. Mechanical feedback • Radiation pressure can drive the observed molecular outflows (e.g., Murray et al., 2005) • See Susanne Aalto’s talk: flow prominent in HCN  dense gas • Highest outflow velocities observed in H2O • Key process in linking ULIRGs and QSOs? (Fischer et al., 2010) Feedback in (U)LIRGs (Feruglio et al., 2010)

  19. H2O in HerCULES red = wet Feedback in (U)LIRGs

  20. Sample spectrum: Zw049057 Feedback in (U)LIRGs

  21. Zw049057details Feedback in (U)LIRGs

  22. H2O is not XDR-driven • Only 3 bona fide AGNs in H2O sample (Mrk231, IRAS F051892524, and Arp299A) • Some pure starbursts in H2O sample (e.g., IRAS 172080014) • AGNs without strong H2O emission (e.g., NGC1365, NGC7469) • NGC7469 shows no strong H2O lines but strong OH+ emission  XDR? • All of this must be compared to CO ladder PDR/XDR analysis Feedback in (U)LIRGs

  23. Luminosity dependence • Radiatively excited H2O emission ubiquitous in ULIRGs, but also seen in some LIRGs (young starbursts?) • Detection of weak H2O lines in many LIRGs and in M82 shows plenty of gas-phase H2O  key feature is the prominence of infrared-opaque clouds Feedback in (U)LIRGs

  24. Outline • Introducing HerCULES • H2O emission in (U)LIRGs • Radiation pressure dominated disks in (U)LIRGs Feedback in (U)LIRGs

  25. The X-factor • Converting CO flux (luminosity) into H2 column density (mass): (MW: =4; ULIRGs: =0.8) Warning: discussions of the X-factor have been the death-blow for many conferences. (U)LIRG sample (Papadopoulos, Van der Werf, Isaak & Xilouris, in prep.) Feedback in (U)LIRGs

  26. The X-factor and optical depth Highly turbulent motions  low optical depths ( high 12CO/13CO line ratios)  low X-factor (e.g., ULIRGs: X=0.8,Downes & Solomon 1997) NB: Tline is Tb of the line, not kinetic temperature Feedback in (U)LIRGs

  27. Calculating X-factors • Sample of 70 (U)LIRGs, 12CO 10, 21, 32, (43, 65) and 13CO 10, (21) lines • 2 component model: high excitation and low excitation component • X-factor explicitly calculated using non-LTE excitation model and finite optical depths Feedback in (U)LIRGs

  28. Distribution of X-factors Assumptions: • Orion-like high excitation component (not needed with denser coverage of CO ladder  Herschel) • Radiation pressure supported disk  LFIR/M(star forming gas) = constant (observed: LFIR/LHCN = constant; e.g., Gao & Solomon, Wu et al.) Results: • X-factors cluster between 0.5 and 1 (cf., Downes/Solomon value of 0.8 for ULIRGs) with tail up to and exceeding Milky Way values • Most (but not all!) ULIRGs have low X-factors (U)LIRG sample (Papadopoulos, Van der Werf, Isaak & Xilouris, in prep.) Feedback in (U)LIRGs

  29. Getting at X • Derive X from 12CO 10  65 + 13CO 10 (or 21); ideally, use HCN lines as well • Can be used at high z too, but 13CO is challenging • Why did Downes & Solomon get it right without 13CO? • High quality data showing turbulent velocity field • Correctly produced low optical depth • Getting the optical depth right is key Feedback in (U)LIRGs

  30. Summary and outlook • Radiatively excited H2O lines select infrared-opaque nuclear regions such as found in local ULIRGs. • IR radiation pressure can be an important dynamical factor and may lead to Eddington-limited star formation. • X-factors in these regions can be derived from CO lines • Rich field for ALMA at low and high z Feedback in (U)LIRGs