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Paper: Proto--Galaxies and the Hubble Sequence
Volume: 275, Disks of Galaxies: Kinematics, Dynamics and Perturbations
Page: 414
Authors: Williams, P. R.; Nelson, A. H.
Abstract: In a series of 57 Treecode-SPH galaxy formation simulations including star formation, the links between the bulk properties of the initial proto-galactic clouds and the morphological type of the resultant numerical galaxies was investigated (Williams 1998). Simple initial conditions were adopted, consisting of a uniform density sphere in solid body rotation and Hubble expansion. Spiral arm morphology is one of the principal morphological indicators in the classical Hubble sequence, which we focus on here. The six numerical galaxies below demonstrate the range in spiral arm morphology which resulted from variations in the initial angular momentum and initial density (the total mass was held constant at 5× 1011 Modot, initially 10% gas and 90% collisionless dark matter by mass), and show how flocculent and open (later-type) spiral structure was more prevalent in the simulations with higher initial angular momentum and lower initial density. The top and bottom rows of plots have dimensionless spin parameters λi=0.07 and 0.03 respectively; while in the three columns, from left to right, the initial densities were 0.95, 0.16, and 0.09 × 10-3 Modotpc-3.
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