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Observing the End of Cold Flow Accretion using Halo Absorption Systems
- Source :
- ApJ (2011) 735 L1
- Publication Year :
- 2010
-
Abstract
- We use cosmological SPH simulations to study the cool, accreted gas in two Milky Way-size galaxies through cosmic time to z=0. We find that gas from mergers and cold flow accretion results in significant amounts of cool gas in galaxy halos. This cool circum-galactic component drops precipitously once the galaxies cross the critical mass to form stable shocks, Mvir = Msh ~ 10^12 Msun. Before reaching Msh, the galaxies experience cold mode accretion (T<10^5 K) and show moderately high covering fractions in accreted gas: f_c ~ 30-50% for R<50 co-moving kpc and N_HI>10^16 cm^-2. These values are considerably lower than observed covering fractions, suggesting that outflowing gas (not included here) is important in simulating galaxies with realistic gaseous halos. Within ~500 Myr of crossing the Msh threshold, each galaxy transitions to hot mode gas accretion, and f_c drops to ~5%. The sharp transition in covering fraction is primarily a function of halo mass, not redshift. This signature should be detectable in absorption system studies that target galaxies of varying host mass, and may provide a direct observational tracer of the transition from cold flow accretion to hot mode accretion in galaxies.<br />Comment: 6 pages, 2 figures. Minor changes to match published version (results unchanged)
- Subjects :
- Astrophysics - Cosmology and Extragalactic Astrophysics
Subjects
Details
- Database :
- arXiv
- Journal :
- ApJ (2011) 735 L1
- Publication Type :
- Report
- Accession number :
- edsarx.1012.2128
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1088/2041-8205/735/1/L1