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Paper: Spiral Structure Dynamics in Pure Stellar Disk Models
Volume: 480, Structure and Dynamics of Disk Galaxies
Page: 145
Authors: Valencia-Enríquez, D.; Puerari, I.
Abstract: In order to understand the physical mechanism underlying non-steady stellar spiral arms in disk galaxies we performed a series of N-body simulations with 1.2 and 8 million particles. The initial conditions were chosen to follow Kuijken-Dubinski models. In this work we present the results of a sub-sample of our simulations in which we experiment with different disk central radial velocity dispersion (σR,0) and the disk scale height (zd). We analyzed the growth of spiral structures using 1D and 2D Fourier Transform (FT1D and FT2D respectively). The FT1D was used to obtain the angular velocities of non-axisymmetric structures which grow in the stellar disks. In all of our simulations the measured angular velocity of spiral patterns are well confined by the resonances given by the curves Ω±κ/m. The FT2D gives the amplitude of a particular spiral structure represented by two Fourier frequencies: m, number of arms; and p, related to the pitch angle as atan(–m/p). We present, for the first time, plots of the Fourier amplitude |A(p,m)| as a function of time which clearly demonstrates the swing amplification mechanism in the simulated stellar disks. In our simulations, the spiral waves appear as leading spiral structures evolving towards open trailing patterns and fade out as tightly wound spirals.
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