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A Clash of Clusters Provides New Clue to Dark Matter
Special ACKS Seminar: Dragan Huterer
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ACKS Seminar: David Tytler (University of California, San Diego)
| What | ACKS |
|---|---|
| When |
20 March 08 from 04:00 pm to 05:00 pm |
| Where | SLAC, 3rd Floor KAVLI Conf Room |
| Contact Name | Lukasz Stawarz |
| Contact Email | stawarz@slac.stanford.edu |
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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 astrophysics (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).
Stanford High Performance Computing Conference IV