1 / 12

The metallicity of the high column density Ly a forest at 2 < z < 3.5

The metallicity of the high column density Ly a forest at 2 < z < 3.5. Tae-Sun Kim Col: Bob Carswell. Institute of Astronomy. QSO absorption line systems : the Ly- a forest highly ionised , low density absorption lines. QSO. Metal lines CIV, SiIV, MgII, FeII.

carson
Télécharger la présentation

The metallicity of the high column density Ly a forest at 2 < z < 3.5

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The metallicity of the high column densityLya forestat 2 < z < 3.5 Tae-Sun Kim Col: Bob Carswell Institute of Astronomy

  2. QSO absorption line systems: the Ly-a forest highly ionised, low density absorption lines QSO Metal lines CIV, SiIV, MgII, FeII HI lines ( < 1017 cm-2) Cen’s Webpage

  3. Observations: • ~90% of clouds with N(HI) > 1015cm-2are enriched with CIV (up to z ~ 5) • Highly ionised => ionisation correction • Relatively cool, T<105 K • Highly inhomogeneous, density-dependent, z-independent • [C/H] = -3.47 + 0.08 (z - 3) + 0.65 (log d – 0.5) (Schaye et al. 2003)

  4. Metal enrichment of the IGM: Galaxy-IGM interplay • Metallicity of systems N(HI) = 1015-19 cm-2 • Redshift dependence? IGM ? Pettini (2004) Galaxies: spirals? N(HI) = 1015-19 cm-2

  5. Difficulties for N(HI) = 1015-17cm-2 zzzzzzzz • Saturation • Not many available ionic transitions • Sensitive to the UV background Most ionic lines are not saturated!!

  6. Observations and Data reduction • VLT/UVES Archive data • R~ 45000, S/N ~ 30-50 • Voigt profile fitting with VPFIT: NHI= 1015-17 cm-2 QSOs zem Forest redshifts # of systems PKS1448-232 2.219 1.986-2.175 1/0/1 PKS0237-23 2.223 1.986-2.179 1/0/1 HE2217-2818 2.406 1.986-2.360 3/0/3 HE1122-1648 2.412 1.986-2.365 2/0/2 Q0329-385 2.435 1.986-2.389 2/0/2 Q0002-422 2.767 2.183-2.717 6/3/6 PKS2126-158 3.280 2.669-3.222 12/3/5

  7. Normalized flux Normalized flux N(HI) = 1015.10 cm-2 N(HI) = 1015.81 cm-2

  8. With other ions With other ions CIV only CIV only N(CIV)/N(HI) vs N(HI) * ◊ :Songaila & Cowie (1996) : z ~ 3

  9. Photoionisation model: CLOUDY • Plane-parellel geometry • Solar-abundance pattern • Haardt-Madau QSO+Galaxies UV background • For the CIV-only systems: • Schaye density law (2001) • For the metal systems: • CIV, CII, SiIV, SiII, SiIII, OVI abundances nH ~ 1.23 x 10-14 NHI 2/3 T40.17 G122/3 cm-3 Improve measurement of [C/H]

  10. [C/H] vs N(HI) CIV only [C/H]med = -3.03 OVI: photoionisation failed With other ions [C/H]med = -1.96 ◊ :Dessauges-Zavadsky et al. (2003) : Songaila & Cowie (1996) : z ~ 3 *

  11. [C/H] vs z OVI: photoionisation failed With other ions ◊ :Dessauges-Zavadsky et al. (2003) : Songaila & Cowie (1996) : z ~ 3 * CIV only

  12. Conclusions • 17 systems with N(HI) = 1015-17 cm-2 • Photoionisation model with QSO + Galaxies reproduces the metal line ratios • For the 6 CIV-only systems: [C/H]med = -3.03 nHI ~ 10-3.5 cm-3 T ~ 4 x 104 K • For the 8 systems with additional ions the inferred [C/H] is similar to that of sub-DLAs [C/H]med = -1.96 nHI ~ 10-2.5 cm-3 T ~ 4 x 104 K • At d ~ 70 the measured [C/H] is consistent with [C/H] from Schaye at al. (2003)

More Related