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Extra-planar gas at low and high redshifts

Extra-planar gas at low and high redshifts. Filippo Fraternali Department of Astronomy, University of Bologna, Italy. Extra-planar gas now and then. Gaseous halos in edge-on galaxies and in galaxies at intermediate inclinations Are they observable at high-z?

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Extra-planar gas at low and high redshifts

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  1. Extra-planar gas at low and high redshifts Filippo Fraternali Department of Astronomy, University of Bologna, Italy

  2. Extra-planar gas now and then • Gaseous halos in edge-on galaxies and in galaxies • at intermediate inclinations • Are they observable at high-z? • Star Formation and Gas Accretion History

  3. Extra-planar gas in edge-on galaxies

  4. NGC 891: HI observations > 200 hrs with the WSRT Total Mass of the HI halo MHI ~1.2 x 109 M ~30% MHItot Oosterloo, Fraternali, Sancisi 2007 Sancisi et al. 2008, A&ARv

  5. Thin disk Artificial data-cubes NGC 891 and models HI Channel maps Halo gas VSys

  6. Thin disk Models with lagging halo NGC 891 and models HI Channel maps Halo gas VSys

  7. NGC891 at high redshifts • Spatial resolution (seeing) 0”.6 ~ 3.6 kpc • Spectral resolution () ~ 10 km s-1 • No SB/flux corretion z = 0.5 (VLT - FLAMES, O[II]) • Spatial resolution (seeing) 0”.6 ~ 5 kpc • Spectral resolution () ~ 40 km s-1 • No SB/flux corretion 1.5<z<2.5 (VLT - SINFONI, H)

  8. NGC891 at high redshift z = 0.5 - FLAMES z = 2 - SINFONI Local

  9. Data cubes z = 0.5 - FLAMES z = 2 - SINFONI Halo features observable at high-z

  10. Vsys Rotation curves of edge-ons Line profile VROT To observer Line of nodes

  11. NGC 891 vrot~15 km s-1 kpc-1 Rotational Gradient Fraternali et al. 2005, ASPC Strong rotational gradient with z

  12. Original data High-z Recovering rotation curves z = 0.5 - FLAMES z = 2 - SINFONI Disk rotation curve Disk rotation curve At 5 kpc above the plane Kinematics can be studied at high z!

  13. Optical Neutral gas (VLA) Same scale! Fraternali et al. 2002, ApJ Extra-planar gas in inclined galaxies

  14. NGC 2403: halo gas 150 km/s Halo gas Halo gas Total Mass of the HI halo MHI ~3 x 108 M ~10% MHItot Fraternali, Oosterloo, Sancisi & van Moorsel 2001

  15. z = 0.5 - FLAMES Data cubes Beards are difficult to observe at high-z z = 2 - SINFONI

  16. Velocity fields z = 0.5 - FLAMES z = 2 - SINFONI

  17. Recovering N2403 rotation curve z = 0.5 - FLAMES z = 2 - SINFONI

  18. Velocity dispersion fields z = 0.5 - FLAMES z = 2 - SINFONI Only resolution effects!

  19. Gas accretion history

  20. SFH in the Milky Way Cignoni et al. 2008 Star formation history Panter et al. 2006 Hippelein et al. 2003

  21. Keres et al. 2005 Gas accretion history • It should follow SFR • Cold or prone to cool • Some other observable • effect?

  22. Filament Counter-rotating clouds 580 km/s Accretion: high velocity gas NGC891 15 kpc Energy needed 1054-55 erg Accretion ~ 2 x 107 M/108yr ~ 0.2 M yr-1 Forbidden in a fountain

  23. Accretion: High Velocity Clouds Low metallicity Z=0.15 solar Low metallicity Z=0.1-0.4 solar HVCs masses ~< 107 Maccretion rate ~ 0.2 M/yr Most of the accretion is hidden Wakker 2007; Wakker & Van Woerden 1997; Tripp et al. 2003

  24. Minor mergers? Detected in ~25% of galaxies Masses ~ 1-10 x 108 MO Life time ~ 1-2 dyn time Global accretion rates ~ 0.2 MO/yr Most of the accretion is hidden Sancisi et al. 2008, A&ARv

  25. Gas dynamics in a pure fountain Fountain gas has too high angular momentum Fraternali & Binney, 2006, 2008 See also Heald et al. 2007

  26. Fountain + Accretion in NGC891 Best-fit Accretion Rate ~ 3 Moyr-1 Compare to SFR ~ 4 Moyr-1 Halo gas: ~90% from fountain ~10% accreted Fountain must sweep up ambient gas at the rate ~ SFR NGC891

  27. Conclusions 1. Local galaxies are surrounded by massive gaseous haloes with complex structure 2.Halos in edge-on galaxies can be studied at high-z, beards not clear 3. Gaseous halos are the key to study gas accretion

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