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H I in galaxies from z = 0.002 to z = 0.2

H I in galaxies from z = 0.002 to z = 0.2. Thijs van der Hulst Kapteyn Astronomical Institute University of Groningen. Kapteyn astronomical institute. Open Questions. When and how quickly did the gas settle in the dark matter potential wells

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H I in galaxies from z = 0.002 to z = 0.2

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  1. HIin galaxies from z = 0.002 to z = 0.2 Thijs van der Hulst Kapteyn Astronomical Institute University of Groningen Kapteyn astronomical institute

  2. Open Questions • When and how quickly did the gas settle in the • dark matter potential wells • - Where and how did gas get converted into stars • When and how did the merging process develop • What is the importance of gas accretion versus merging Radiotelescopes can trace the neutral gas extremely well ( to go beyond z = 0.2 we need SKA )

  3. COLD GAS HI observations local universe - Extended HI disks with outer spiral structure - Large majority of disks WARPED and LOPSIDED - Large reservoirs extra-planar gas - Lumpy HI structures (clouds, tails, filaments) around galaxies Result of recent minor mergers and accretion? Sancisi et al. A&A Rev., 2008

  4. HI VLA WSRT 1976 HI WSRT WARPS LOPSIDEDNESS

  5. HI masses in outer structures 108 - 109 Mʘ 3x108 Mʘ

  6. EXTENDED HI (note the spiral structure) opticalNGC 5055neutral hydrogenWSRT same scale Battaglia et al. 2005

  7. EXTENDED HI (spiral arms) NGC 5055neutral hydrogenWSRT GALEX same scale Battaglia et al. 2005

  8. NGC 6946 opticalneutral hydrogen WSRT same scale Boomsma et al. 2007

  9. Some star formation also in outer disk NGC 6946 neutral hydrogen Deep B-band WSRT same scale A. Ferguson 2007 Boomsma et al. 2007

  10. HIGH VELOCITY CLOUDS ( total amount ~3 x 108 Mʘ )

  11. NGC 6946 Accretion? HI map WSRT Boomsma et al. 2007

  12. NGC 2403 HI VLA Anomalous gas 3x108Mʘ model thin disk Fraternali et al. 2001

  13. NGC 891 Anomalous HI ~ 1 x 108 Mʘ Fraternali, 2007

  14. Extra-planar HI MILKY WAY, NGC 891, NGC 2403 M 31, NGC 4559, NGC 253, UGC 7321, NGC 5775, NGC 6946

  15. Emerging picture: HI disk • extended with outer spiral structure • warped • lopsided • porous Extra-planar HI (high velocity clouds) ACCRETION?

  16. Local Universe HI detection limits: Column densities 1 x 1019 cm-2 Masses 1 x 106 Mʘ Accreted HI 107 - 109 Mʘ Time scales 108 - 109 yrs Galaxy fraction 25 - 50 % Accretion rate 0.1 - 0.5 Mʘ/ yr

  17. SUMMARY 1. Spiral structure and star formation in outer HI disks 2. Most galaxies warped and lopsided 3. Large reservoirs of extra-planar HI 4. Cold gas lumpy accretion at a mean rate of 0.1 – 0.5 Mʘ / yr 25 – 50 % of all galaxies accrete lumps of gas of 107-9 Mʘ

  18. HI near the center of the Virgo cluster 3.8 x 108 Mʘ NGC 4388 Oosterloo & van Gorkom, 2005, A&A 437, 19

  19. The Amazing NGC 7426 >300 h-1 kpc - ‘Normal Elliptical - Two tails, 185, 125 h-1 kpc in length! - 4 x 109 h-2 Mʘ - NHI (min) = 1019 cm-2 - Tails aligned with Pisces-Perseus super cluster structure Schiminovich, van Gorkom et al.

  20. Present state of the art: imaging HI emission out to z = 0.2 240 hour integration with WSRT Verheijen, van Gorkom et al. 2007

  21. SKA goals for deep fields: • get to MHI* galaxies out to z = 2 • detect HVC mass objects to z = 0.2 • detect dwarf galaxies to z = 0.5

  22. Number of galaxies detectable as a function of redshift per square degree

  23. Phase-1 SKA: Number of galaxies / sq. deg. as a function of redshift

  24. Detection limits for SKA for t = 12 hours

  25. Phase-1 SKA Detection limits for t = 12 hours

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