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The connection between galaxies and quasar absorption lines

The connection between galaxies and quasar absorption lines. Lise Christensen. Quasar absorption lines. Ly a forest. Metal lines. LLS. DLA. Types of systems. Ly a forest : N (H I ) < 10 17 cm -2 LLS : 10 17 < N (H I ) < 2*10 20 cm -2

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The connection between galaxies and quasar absorption lines

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  1. The connection between galaxies and quasar absorption lines Lise Christensen

  2. Quasar absorption lines Lya forest Metal lines LLS DLA

  3. Types of systems Lya forest :N(H I) < 1017 cm-2 LLS: 1017 < N(H I) < 2*1020 cm-2 DLA : N(H I) > 2*1020 cm-2 Charlton, 2000

  4. Column density distribution b is roughly =1.5 over 10 decades most mass is contained in high N systems (neutral gas only) Evidence for a steeper slope at DLA column densities Petitjean et al. 1993

  5. Neutral gas density DLA Mass in stars (SDSS) evolution with z ? DLAstars DLAs are reservoirs for galaxy formation? 21 cm observations Rao et al. 2005 Prochaska et al. 2005 Zwaan et al. 2005

  6. Metal lines- from high resolution observations

  7. DLA metallicities Prochaska et al. 2003

  8. What we know about DLAs: • N(H I) as galaxy disks – but are they disks? • Metal enriched – star formation has taken place [M/H] between halo and disk stars Slow evolution • Reservoirs for star formation? • In what type of galaxies do DLAs reside?

  9. Purpose of the integral field spectroscopic survey • What types of galaxies harbor DLAs? • Large disks or small dwarfs? • Understand proto-galaxies • DLA galaxies present an alternative selection to flux limited surveys • Look for emission lines from the galaxies hosting DLAs • SFRs, Impact parameters, and sizes • Main parts: • Low redshift: Search for optical emission lines • High redshift (z > 2): search for Lyman-a emission

  10. Observations are done with: PMAS= Potsdam Multi Aperture Spectrophotometer 16*16 fibres connected to lens array (no loss between fibres) 8”*8” field of view ( in our setup) 3.5 m telescope at Calar Alto, Spain IFS advantages: Imaging and spectroscopy simultaneously No slit-losses Pointing less crucial Spectral resolution independent on spatial sampling and seeing The PMAS instrument

  11. Method

  12. Method d l a

  13. Previous low-z studies: Low-z : ~30 known DLA systems – 14 confirmed DLA galaxies 3C 336, z = 0.927 DLA at z = 0.656 24000 s WFPC2 archive image (Steidel et al 1997)

  14. [O II] at z=0.656 But where is the z=0.656 DLA galaxy? z =0.931 R=24.5 z=0.8908 R=23.5

  15. Abundances PHL 1226 – subDLA at z=0.16 projected distance: 18 kpc (Bergeron et al. 1988) Christensen et al. 2005

  16. Abundances Figure from Pettini et al, 2004 G4: Christensen et al. 2005 DLA metallicities could be biased by gradient compare metallicities from emission and absorption

  17. DLAs at high redshifts (z>2) >500 DLA systems known – 6 confirmed…(3 intervening) Q2233+131, z = 3.3 Sub-DLA at z = 3.15 m~25 Djorgovski et al 1996, Christensen et al. 2004

  18. Visualisation – long slits

  19. Visualisation – narrow bands - cubes l l

  20. Movies Looping through a cube of Q2233+131, Sub-DLA @ z =3.15

  21. Candidate DLA galaxies Results: high-z DLA survey • 14 DLAs (+ 8 sub-DLAs) towards 9 QSOs • 8 good candidates found – but only detected at the 3-4s levels • Line flux in the range 3-10*10-17erg cm-2 s-1 • Impact parameters from 1 - 4” (10 - 40 kpc)

  22. DLA galaxy; Line fluxes; Impact parameters ; masses ; SFRs Red symbols from compilation in Moeller et al. 2002

  23. DLA galaxy; Line fluxes ;Impact parameters; masses ; SFRs Exponential fit Scale length 30+/-16 kpc 5+/-2kpc

  24. DLA galaxy; Line fluxes ;Impact parameters; masses ; SFRs Average predicted impact parameters from simulations +low-z data from Chen et al. 2005

  25. DLA galaxy; Line fluxes ; Impact parameters ;masses ; SFRs This mass is in neutral gas; M(H I) (MW has 3*109 M ) Does this imply that DLA galaxies are L* galaxies? No. This is neutral gas mass only. MW mass ~1011 M (in stars) Numerical simulations by Nagamine et al. 2004 suggest M*/Mgas=3 at z=3 M(DLA gal) = 1010 M ~10% M(MW)

  26. DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs Schmidt-Kennicutt law:

  27. DLA galaxy; Line fluxes ; Impact parameters ; masses ;SFRs Luminosity selected galaxies Lilly et al. 1995, Steidel et al. 1999

  28. DLA galaxy; Line fluxes ; Impact parameters; masses ; SFRs Dust obscuration bias? Comoving SFR DLAs: Wolfe et al. 2005, Storrie-Lombardi et al. 2000, Peroux et al 2003, Prochaska et al 2005

  29. Summary • IFS able to identify faint emission lines • independent confirmation is needed • Lya properties consistent with known DLA galaxies • Impact parameters indicate large disks large impact parameters at high and low-z • Disks are massive, but not necessarily luminous • Average SFR consistent with a Schmidt-Kennicutt law assuming radial sizes of 10 kpc • DLAs do not dominate the comoving SFR missing very high N(HI) DLAs in surveys ? 6. DLA metallicities biased by gradients?

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