Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-05-25
Mon.Not.Roy.Astron.Soc.373:1265-1292,2006
Astronomy and Astrophysics
Astrophysics
31 pages, accepted to MNRAS, minor revisions
Scientific paper
10.1111/j.1365-2966.2006.10989.x
We investigate models of self-consistent chemical enrichment of the intergalactic medium (IGM) from z=6 to 1.5, based on hydrodynamic simulations of structure formation that incorporate galactic outflows. Our main result is that outflow parameterizations based on momentum-driven winds as seen in local starburst galaxies provide the best agreement with observations of CIV absorption at z~2-5. Such models sufficiently enrich the high-z IGM to produce a global mass density of CIV absorbers that is relatively invariant from z=5.5 to 1.5, in agreement with observations. This occurs despite an increase in the volume-averaged metallicity by x5-10 over this redshift range, because energy input from outflows causes a drop in the global ionization fraction of CIV. Comparisons to observed CIV column density and linewidth distributions and CIV-based pixel optical depth ratios provide significant constraints on wind models. Our best-fitting models show mean IGM temperatures only slightly above our no-outflow case, metal filling factors of just a few % with volume-weighted metallicities around 0.001 at z~3, significant amounts of collisionally-ionized CIV absorption, and a metallicity-density relationship that rises rapidly at low overdensities and flattens at higher ones. In general, we find that outflow speeds must be high enough to enrich the low-density IGM at early times but low enough not to overheat it, and concurrently must significantly suppress early star formation while still producing enough early metals. It is therefore non-trivial that locally-calibrated momentum-driven wind scenarios naturally yield the desired strength and evolution of outflows, and suggest that such models represent a significant step towards understanding the impact of galactic outflows on galaxies and the IGM across cosmic time.
Dav'e Romeel
Oppenheimer Benjamin Darwin
No associations
LandOfFree
Cosmological Simulations of Intergalactic Medium Enrichment from Galactic Outflows does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Cosmological Simulations of Intergalactic Medium Enrichment from Galactic Outflows, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cosmological Simulations of Intergalactic Medium Enrichment from Galactic Outflows will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-119651