Hierarchical formation of bulgeless galaxies: why outflows have low angular momentum

Type Journal Article
Names C. B. Brook, F. Governato, R. Roškar, G. Stinson, A. M. Brooks, J. Wadsley, T. Quinn, B. K. Gibson, O. Snaith, K. Pilkington, E. House, A. Pontzen
Publication Monthly Notices of the Royal Astronomical Society
Volume 415
Issue 2
Pages 1051-1060
Date August 1, 2011
Short Title Hierarchical formation of bulgeless galaxies
URL http://adsabs.harvard.edu/abs/2011MNRAS.415.1051B
Library Catalog NASA ADS
Abstract Using high resolution, fully cosmological smoothed particle hydrodynamical simulations of dwarf galaxies in a Lambda cold dark matter Universe, we show how high redshift gas outflows can modify the baryon angular momentum distribution and allow pure disc galaxies to form. We outline how galactic outflows preferentially remove low angular momentum material due a combination of (a) star formation peaking at high redshift in shallow dark matter potentials, an epoch when accreted gas has relatively low angular momentum, (b) the existence of an extended reservoir of high angular momentum gas in the outer disc to provide material for prolonged SF at later times and (c) the tendency for outflows to follow the path of least resistance which is perpendicular to the disc. We also show that outflows are enhanced during mergers, thus expelling much of the gas which has lost its angular momentum during these events, and preventing the formation of ‘classical’, merger driven bulges in low-mass systems. Stars formed prior to such mergers form a diffuse, extended stellar halo component similar to those detected in nearby dwarfs.
Tags GALAXIES: EVOLUTION, galaxies: bulges, galaxies: formation, galaxies: starburst
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