Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2009-01-20
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
7 pages, to appear in proc. "Galaxy Evolution: Emerging Insights and Future Challenges", ASP (uses asp2006.sty)
Scientific paper
We present predictions for galactic halo baryon fractions from cosmological hydrodynamic simulations with a well-constrained model for galactic outflows. Without outflows, halos contain roughly the cosmic fraction of baryons, slightly lowered at high masses owing to pressure support from hot gas. The star formation efficiency is large and increases monotonically to low masses, in disagreement with data. With outflows, the baryon fraction is increasingly suppressed in halos to lower masses. A Milky Way-sized halo at z=0 has about 60% of the cosmic fraction of baryons, so "missing" halo baryons have largely been evacuated, rather than existing in some hidden form. Large halos (>10^13 Mo) contain 85% of their cosmic share of baryons, which explains the mild missing baryon problem seen in clusters. By comparing results at z=3 and z=0, we show that most of the baryon removal occurs at early epochs in larger halos, while smaller halos lose baryons more recently. Star formation efficiency is maximized in halos of ~10^13 Mo, dropping significantly to lower masses, which helps reconcile the sub-L* slope of the observed stellar and halo mass functions. These trends are predominantly driven by differential wind recycling, namely, that wind material takes longer to return to low-mass galaxies than high-mass galaxies. The hot gas content of halos is mostly unaffected by outflows, showing that outflows tend to blow holes and escape rather than deposit their energy into halo gas.
No associations
LandOfFree
Missing Halo Baryons and 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 Missing Halo Baryons and Galactic Outflows, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Missing Halo Baryons and Galactic Outflows will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-683872