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Hot Gas in Damped Lyman- a Systems Hidden Baryons & Metals in Galactic Halos at z=2-4

Hot Gas in Damped Lyman- a Systems Hidden Baryons & Metals in Galactic Halos at z=2-4. Andrew Fox (ESO-Chile) with P. Petitjean, C. Ledoux, R. Srianand, J. Prochaska, A. Wolfe. * In IGM Simulations by Oppenheimer & Davé. z=2-4: Most Baryons still in Diffuse IGM.

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Hot Gas in Damped Lyman- a Systems Hidden Baryons & Metals in Galactic Halos at z=2-4

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  1. Hot Gas in Damped Lyman-a SystemsHidden Baryons & Metals in Galactic Halos at z=2-4 Andrew Fox (ESO-Chile) with P. Petitjean, C. Ledoux, R. Srianand, J. Prochaska, A. Wolfe

  2. * In IGM Simulations by Oppenheimer & Davé

  3. z=2-4: Most Baryons still in Diffuse IGM IGM Simulations by Oppenheimer & Davé

  4. Damped Lyman-a Systems: Observing gas in/around protogalaxies • N(H I)>2x1020 cm-2 • Identified by damping wings on Lyman- line • Select galaxies (or their halos) through absorption (independent of galaxy mass) • Large samples exist at both medium and high resolution Pontzen et al. (2008) DLA Simulations

  5. Survey for High Ions in DLAs O VI 1031, 1037 Ion. Potential =114 eV N V 1238, 1242 Ion. Potential =77 eV C IV 1548, 1550 Ion. Potential =48 eV Si IV 1393, 1402 Ion. Potential =33 eV O5+

  6. O+4  O+5 electron (T300 000 K) Collisional ionization photon (E>113.9 eV) Photoionization

  7. O+6  O+5

  8. Spectra from VLT/UVES v (km s-1) v (km s-1)

  9. DLA Plasma: Kinematic Measurements System line width (Dv) Component line width (b-value) –200 km/s 0 200 km/s

  10. Component line width distributionBased on Voigt Profile Fits to 12 DLAs with O VI Characteristic of warm photoionizedplasma Evidence for multiple plasma phases Characteristic of hot, collisionally-ionized plasma Fox et al. 2007a

  11. DLA High-ion Kinematics Wolfe & Prochaska (2000) Fox et al. (2007b) Broader Dv for high ions than low ions  different energy source, ionizing and dispersing metal atoms over large Dv. Gal. winds? Accretion?

  12. High-ion system velocity width correlates with metallicity

  13. DLA Plasma: A Baryon & Metal Reservoir? Milky Way (DLA) [O/H]=0 sub-DLA at z=2.67 [O/H] =[O I/H I]= –1.64 ± 0.07 O VI 1031 In both cases, the O VI line is ~70% deep → O VI in DLAs/sub-DLAs is surprisingly strong given the metallicity

  14. Ionization versus temperature Models from Gnat & Sternberg (2007); f(O VI)<0.2 in photo-ionized models too

  15. Fox et al. 2009 O VI (purple):N(Hot H II)/N(H I)> 0.4 we know (H I in DLAs, z=3)=(1.0±0.1)10-3(Prochaska+ 2005, Péroux+2005) Baryon content (Hot H II, DLAs) > 410-4  Metal content (Hot H II, DLAs) >1.510-7 (~1% of z=2.5 metal budget)

  16. Production of warm/hot plasma in galaxy halos (at z=2-4) Galactic Winds (Outflow) Hot-mode accretion (Inflow) Simulations from Kawata & Rauch (2007) Simulations from Dekel & Birnboim (2007)

  17. High Ions in z=2-4 DLAs: Summary • WHAT WE KNOW (OBSERVATIONALLY) • Detection rate of C IV & Si IV in DLAs (observed at high res.) is 100% • → neutral gas always “shadowed” by ionized gas • High-ion col. densities & Dv correlate with neutral-phase metallicity • Dv broader for high ions than low ions: • Dv(C IV)~250 km s-1; Dv(Si II)~80 km s-1 • b-values broader for O VI than for C IV & Si IV→ plasma is multi-phase • Large dataset for constraining simulations • WHAT WE’D LIKE TO KNOW • What is metallicity in high-ion phase? Does it equal low-ion metallicity? • → can refine N(H II) & baryon budget estimates • Is warm/hot plasma around galaxies produced by accretion,outflow, or both? • Outflow naturally explains metals without need for pre-enrichment • Hot-mode accretion predicted in galaxies with M ≥ 1011.5M • What is fate of metals in warm/hot plasma? Locked up? tcool (60 Gyr) (T/106)2.7 (d/50)-1 if Z=0.1 Z

  18. zQSO=2.85

  19. Q) Do we expect photoionized O VI in galaxy halos at z=2-3?A) It depends (on the radiation field) Almost 1 dex uncertainty inJnat 113.9 eV! Simcoe et al. (2004), z=3

  20. Ledoux et al. 2006, using VLT/UVES:6 correlation between metallicityand velocity width oflow-ionprofiles. If L M ( Dv2) Same slope as L-Z relation for local galaxies (Tremonti et al.) Mass-Metallicity relation?

  21. Metal Budget at z~2.2 ~ See also Pettini (1999, 2004), Pagel (2002), Ferrara+ (2005), Sommer-Larsen & Fynbo (2007) stars gas • Sub-DLA contribution higher than DLA: • more of them; CDDF rises to lower N(H I) (O’Meara+ 2007, Péroux+ 2005) • higher mean [Z/H] (Prochaska+ 2006, Kulkarni+ 2007) • higher ionization level (hidden metals) (Prochaska 1999, Fox+ 2007, • don’t forget O VI phase!)

  22. Imaging of DLA Host Galaxies 5 4 Chen et al. 2005, z<0.65 DLAs  range of host galaxy properties Møller et al. (2002), HST/STIS

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