|List of TYTLER's Presentation(s) ( Updated 20/01/2011 15:18:56 )|
|Precise if your presentation is oral or a poster :||oral|
|Title of your presentation :||Absorption in pairs of QSOs: absence of QSO feedback and winds from galaxies|
The first large sample of absorption lines in the spectra of pairs of QSOs that are close in the sky contains some surprises. The absorbers in the paired QSOs have very similar redshifts, as if the absorption is from blue and not red galaxies. The absorption is not from winds flowing out of galaxies at high velocities,
suggesting that the metals seen in the intergalactic medium are already in place.
We see no change in the absorption from neutral hydrogen in the background QSO as a sight line passes by a foreground QSO. Either the foreground QSO UV is emitted into a narrow beam toward us, or QSOs emit for < 1 Myr at the luminosity we seen.
We use large hydrodynamic numerical simulations to interpret these data, but we can not find a simulation that matches even the intergalactic hydrogen absorption in single QSOs. We may have a problem with the simulations (we need self-shielding and radiative transfer), with the strophysics (we need a less energetic photoionizing spectrum) or with cosmology (we need a higher amplitude for the clustering of matter on small scales, sigma_8 > 0.9).