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HI Column Densities, Kinematics, and Metallicities in Strong MgII Absorbers

HI Column Densities, Kinematics, and Metallicities in Strong MgII Absorbers. Dave Turnshek University of Pittsburgh. Outline: Strong MgII Absorbers (low ionization, neutral gas) HI Column Densities (DLAs and sub-DLAs) Kinematics Element Abundances Model Implications

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HI Column Densities, Kinematics, and Metallicities in Strong MgII Absorbers

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  1. HI Column Densities, Kinematics, and Metallicities in Strong MgII Absorbers Dave Turnshek University of Pittsburgh

  2. Outline: • Strong MgII Absorbers (low ionization, neutral gas) • HI Column Densities (DLAs and sub-DLAs) • Kinematics • Element Abundances • Model Implications • DLA Absorbing Galaxies • Selection Effects (esp. MgII) • Pittsburgh Collaborators: • Sandhya Rao • Michele Belfort-Mihalyi • Daniel Nestor (now U. Florida) • Anna Quider • + SDSS collaborators …

  3. Strong MgII Absorbers(MgIIl2796 REW > 0.3 Å) • Detected in large numbers at 0.4 < z < 2.2 by SDSS (e.g., Nestor, Turnshek, Rao 2005) • Selection biased by gas cross section • Tracers for DLAs when REW2796 > 0.6 Å (Rao, Turnshek, Nestor 2005) • Remainder are mostly sub-DLAs (incomplete?)

  4. MgIIl2796 REW Distribution • Left: MMT + SDSS • Right: SDSS alone

  5. Incidence of MgII REWs: z = 0.4  2.2 • Dashed: no evolution curve (NEC) • Larger REWs decrease relative to NEC at decreasing redshift

  6. HI Column Densities • Rao, Turnshek, Nestor (2005): • HST UV spectra of 197 strong MgII absorbers • MgIIl2796 REW > 0.6 Å: • DLA fraction increases with increasing REW • Mean N(HI) = 4(1020) atoms/cm2 • 0.3 Å < MgIIl2796 REW < 0.6 Å: • Mean N(HI) = 1019 atoms/cm2

  7. Mean HI Column Densities(all strong MgII absorbers)

  8. Mean HI Column Densities all strong MgIIs: only MgII DLAs:

  9. Strong MgII Absorber Kinematics Doublet ratios indicate that strong MgIIs are saturated. Their REWs are mainly indicators of absorption velocity spread. e.g., Petitjean (1998)

  10. DLA Fraction and Mean HI Column Density vs. REW in Velocity Units(all strong MgII absorbers) REW is given in units of km/s instead of Å on the top horizontal axis.

  11. Element Abundances in Strong MgII Absorbers • Use SDSS composite spectra (high S/N) • MgII2796 REW measures kinematics • Metallicities from weak unsaturated lines • Study metallicity - kinematics correlations

  12. Metallicity–Kinematics Correlation(ZnII, CrII, MgII SDSS Composites) Approximately 6000 strong MgII absorbers. Also seen in SiII, FeII, and MnII.

  13. Metallicity–Kinematics Correlation(ZnII and CrII SDSS Composites) ZnII CrII Approximately 6000 strong MgII absorbers. MgIIl2796 REW intervals noted in units of km/s.

  14. DLA Fraction and Mean HI Column Density versus Velocity Spread(all strong MgII absorbers) REW is given in units of km/s instead of Å on the top horizontal axis.

  15. Metallicity–Kinematics Correlation(Zn, Cr, Si, Mn, and Fe) rare large REW systems

  16. Metallicity–Kinematics Correlation(Zn and Cr) (more depletion) (little depletion)

  17. Metallicity–Kinematics Correlation(Zn and Si) (a-enhancement)

  18. Metallicity–Kinematics Correlation(Keck HIRES data, z=1.74.2, taken from Prochaska et al.)

  19. Model Implications (z=0.52) • Kinematic spread at z=12 consistent with predictions of Mo, Mao, White (1998) • DLA galaxy impact parameters at z<1 consistent with Mo, Mao, White (1998) predictions at z=1 • Implications for cosmic SFR • DLAs different from LBGs (Mo, Mao, White 1998) • Application of Kennicutt’s Schmidt Law to DLAs suggests DLAs contribute at low-z, not at high-z (Hopkins, Rao, Turnshek 2005; Rao talk)

  20. DLA Fraction and Mean HI Column Density versus Velocity Spread(all strong MgII absorbers) REW is given in units of km/s instead of Å on the top horizontal axis.

  21. Kinematics and Impact Parameter(Mo, Mao, White 1998)

  22. DLA Galaxy Properties (z<1)(updated from Rao et al. 2003)

  23. Selection Effects • The probability of detecting a DLA absorber is the product of their comoving number density times their gas cross section. • Could we be missing very high N(HI) absorbers with low neutral gas cross section? • Detection of one low cross section system with N(HI) = 1023 atoms/cm2 would require doubling ΩHI • MgII REW selection bias • Not relevant ΩHI [since mean N(HI) flat with REW] • Relevant for cosmic metallicity and DLA galaxy IDs

  24. Ultra-StrongMgII Fields Recent WIYN observations of Nestor et al.

  25. Example of an Ultra-Strong MgII FeII region MgII + MgI region

  26. DLA Galaxy Properties (z<1)(updated from Rao et al. 2003)

  27. Summary: Strong MgII Absorbers • Galaxies Selected by Gas Cross-Section • HST UV: N(HI) – kinematics correlation • SDSS: kinematics – metallicity correlation • Consistency with Mo, Mau, White (1998)? • MgII selection effects need to be incorporated

  28. Extras …

  29. DLA Galaxy Properties (z<1)(updated from Rao et al. 2003)

  30. PKS 1127-145 IRTF K-band imaging of DLA field at z=0.313.

  31. Strong MgII Nearest Neighbors IRTF K-band imaging of DLA and sub-DLA fields at z<1.

  32. Strong MgII Nearest Neighbors IRTF K-band imaging of DLA and sub-DLA fields at z<1.

  33. Schmidt Law from Kennicutt (1998)

  34. DLAs and Cosmic Star Formation Hopkins, Rao, Turnshek (2005) • Hatched region: observed cosmic SFR • Filled circles: DLAs

  35. DLAs and Cosmic Star Formation Hopkins, Rao, Turnshek (2005) • Hatched regions: neutral gas and stellar mass densities predicted from observed cosmic SFR • Filled circles: DLAs

  36. DLAs and Cosmic Star Formation Hopkins, Rao, Turnshek (2005) • Hatched region: metals predicted from observed cosmic SFR • Filled circles: metals from DLAs

  37. DLA Fraction in Strong MgIIs

  38. Mean HI Column Densities all strong MgIIs: only MgII DLAs:

  39. Evolution of Incidence of DLAs Rao, Turnshek, Nestor (2005) • Lower curve: no-evolution • incidence is product of absorber cross-section times absorber number density

  40. Evolution of HI Cosmological Mass Density from DLAs Rao, Turnshek, Nestor (2005) • DLA neutral gas mass is ≈ constant at z=0.54.5, but is 2 times lower at z=0.

  41. SDSS Spectrum of MgII Absorption • z=0.741 MgII absorption system (REW2796 = 2.95Angstroms) Right: Strong MgII doublet and weaker MgI line. Left: Two Strong FeII lines and three weaker MnII lines.

  42. H I 21 cm Maps of Some Nearby Galaxies: VLA and WSRT maps courtesy John Hibbard, NRAO

  43. H I 21 cm Maps of Some Nearby Galaxies: VLA and WSRT maps courtesy John Hibbard, NRAO

  44. H I 21 cm Maps of Some Nearby Galaxies: VLA and WSRT maps courtesy John Hibbard, NRAO

  45. Identification of MgII Absorbing Galaxies Quasar 3C336 Sightline Hubble Space Telescope image of a field with several quasar absorption line system galaxies identified. A galaxy at the DLA redshift (z=0.656) is not visible. Courtesy Chuck Steidel

  46. Identification of DLA Absorbing Galaxies Infrared K-band image of the Q0738+313 sightline with DLAs at z = 0.091 and z = 0.221. IDs put the galaxies at 0.08 and 0.1L*, respectively. Turnshek et al. 2001

  47. Optical Images of Stars in M51: Courtesy NOAO Deep exposure Short exposure

  48. Evolution of Neutral Gas Metal Abundance • Beginning to measure abundances at lower-z, seeing evidence for evolution. Rao et al. 2004

  49. XXX • xxx

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