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Hierarchical formation of bulgeless galaxies - II. Redistribution of angular momentum via galactic fountains


Brook, C B; Stinson, G; Gibson, B K; Roškar, R; Wadsley, J; Quinn, T (2011). Hierarchical formation of bulgeless galaxies - II. Redistribution of angular momentum via galactic fountains. Monthly Notices of the Royal Astronomical Society, 419(1):771-779.

Abstract

Within a fully cosmological hydrodynamical simulation, we form a galaxy which rotates at 140 km s-1, and it is characterized by two loose spiral arms and a bar, indicative of a Hubble-type SBc/d galaxy. We show that our simulated galaxy has no classical bulge, with a pure disc profile at z = 1, well after the major merging activity has ended. A long-lived bar subsequently forms, resulting in the formation of a secularly formed 'pseudo-'bulge, with the final bulge-to-total light ratio of 0.21. We show that the majority of gas which loses angular momentum and falls to the central region of the galaxy during the merging epoch is blown back into the hot halo, with much of it returning later to form stars in the disc. We propose that this mechanism of redistribution of angular momentum via a galactic fountain, when coupled with the results from our previous study which showed why gas outflows are biased to have low angular momentum, can solve the angular momentum/bulgeless disc problem of the cold dark matter paradigm.

Abstract

Within a fully cosmological hydrodynamical simulation, we form a galaxy which rotates at 140 km s-1, and it is characterized by two loose spiral arms and a bar, indicative of a Hubble-type SBc/d galaxy. We show that our simulated galaxy has no classical bulge, with a pure disc profile at z = 1, well after the major merging activity has ended. A long-lived bar subsequently forms, resulting in the formation of a secularly formed 'pseudo-'bulge, with the final bulge-to-total light ratio of 0.21. We show that the majority of gas which loses angular momentum and falls to the central region of the galaxy during the merging epoch is blown back into the hot halo, with much of it returning later to form stars in the disc. We propose that this mechanism of redistribution of angular momentum via a galactic fountain, when coupled with the results from our previous study which showed why gas outflows are biased to have low angular momentum, can solve the angular momentum/bulgeless disc problem of the cold dark matter paradigm.

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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
Language:English
Date:January 2011
Deposited On:22 Jan 2013 16:43
Last Modified:05 Apr 2016 16:22
Publisher:Wiley-Blackwell
ISSN:0035-8711
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1111/j.1365-2966.2011.19740.x

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