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Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-54415

Stewart, K R; Kaufmann, T; Bullock, J S; Barton, E J; Maller, A H; Diemand, J; Wadsley, J (2011). Observing the end of cold flow accretion using halo absorption systems. Astrophysical Journal Letters, 735(1):L1.

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We use cosmological smoothed particle hydrodynamic 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, M vir = M sh ~ 1012 M sun. Before reaching M sh, the galaxies experience cold mode accretion (T < 105 K) and show moderately high covering fractions in accreted gas: fc ~ 30%-50% for R < 50 comoving kpc and N_{H\,\mathsc{i}}>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 M sh threshold, each galaxy transitions to hot mode gas accretion, and fc 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.


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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Date:July 2011
Deposited On:18 Feb 2012 14:12
Last Modified:05 Apr 2016 15:20
Publisher:Institute of Physics Publishing
ISSN:0004-637X (P) 1538-4357 (E)
Publisher DOI:10.1088/2041-8205/735/1/L1
Related URLs:http://arxiv.org/abs/1012.2128

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