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

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Presentation on theme: "Hot Gas in Damped Lyman- Systems Hidden Baryons & Metals in Galactic Halos at z=2-4 Andrew Fox (ESO-Chile) with P. Petitjean, C. Ledoux, R. Srianand, J."— Presentation transcript:

1 Hot Gas in Damped Lyman- 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

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- Systems: Observing gas in/around protogalaxies Pontzen et al. (2008) DLA Simulations N(H I )>2x10 20 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

5 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 O 5+

6 O +4 O +5 electron (T K) Collisional ionization photon (E>113.9 eV) Photoionization

7 O +6 O +5

8 Ion Detection rate in DLAs at z=2-3 Ref C IV, Si IV 100% (74/74) Wolfe & Prochaska 2000 Fox et al. 2007b O VI >34 % (12/35) Fox et al. 2007a Lehner et al N V 13±4 % Fox et al v (km s -1 ) Spectra from VLT/UVES

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

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

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

12 High-ion system velocity width correlates with metallicity

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

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

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

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 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 & v correlate with neutral-phase metallicity v broader for high ions than low ions: v(C IV ) ~250 km s -1 ; v(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 High Ions in z=2-4 DLAs: Summary t cool (60 Gyr) (T/10 6 ) 2.7 ( /50) -1 if Z=0.1 Z WHAT WED 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 M What is fate of metals in warm/hot plasma? Locked up?

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19 QAL Categorylog N(H I ) Notes Ly forest <17 IGM low overdensity ionized Lyman limit systems (LLS) Sub-damped Lyman- (sub-DLA) Damped Lyman- (DLA) systems >20.3 Galaxies overdense neutral z QSO =2. 85

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

21 Mass-Metallicity relation? Ledoux et al. 2006, using VLT/UVES: 6 correlation between metallicity and velocity width of low- ion profiles. If L M ( v 2 ) Same slope as L-Z relation for local galaxies (Tremonti et al.)

22 See also Pettini (1999, 2004), Pagel (2002), Ferrara+ (2005), Sommer-Larsen & Fynbo (2007) stars gas Metal Budget at z~2.2 Sub-DLA contribution higher than DLA: more of them; CDDF rises to lower N(H I ) (OMeara+ 2007, Péroux+ 2005) higher mean [Z/H] (Prochaska+ 2006, Kulkarni+ 2007) higher ionization level (hidden metals) (Prochaska 1999, Fox+ 2007, dont forget O VI phase!) ~

23 4 Imaging of DLA Host Galaxies Chen et al. 2005, z<0.65 DLAs range of host galaxy properties Møller et al. (2002), HST/STIS 5


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