The distribution and baryon content of H I absorbers at z<0.5
Abstract
We combine FUV spectra obtained with FUSE and STIS/e140m of He 0226-4116 (z=0.495), pg 1116+215 (z em=0.177), and pg 1259+593 (z em=0.478) to determine the distribution of column density and doppler width of the Lyα absorber population at z detected in the spectra of these 3 quasars. The high spectral resolution UV spectra allow us to derive simultaneously the redshift, column density, and doppler width of each absorber. Two different populations of H I absorbers appear to be present: narrow and broad H I absorptions that could be tracers of the warm photoionised igm (t k) and warm-hot ionised medium (whim, t ∼ 105-106 k). For a reliable assessment of the baryonic content of the Lyα forest at low z it is crucial to determine the relative numbers of photoionised absorbers vs. hot collisionally ionised absorbers. Preliminary results indicate that 30-40% of the total baryons are in the photoionised igm and at least 20% in the whim. We also discuss the observed evolution of the doppler parameter with redshift.
- Publication:
-
IAU Colloq. 199: Probing Galaxies through Quasar Absorption Lines
- Pub Date:
- March 2005
- DOI:
- 10.1017/S1743921305002565
- Bibcode:
- 2005pgqa.conf..162L