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Properties of barred spiral discs in hydrodynamical cosmological simulations

By David Goz, Pierluigi Monaco, Giuseppe Murante and Anna Curir

Abstract

We present a quantification of the properties of bars in two N-body+ smoothed particle hydrodynamics cosmological simulations of spiral galaxies, named GA and AqC. The initial conditions were obtained using the zoom-in technique and represent two dark matter haloes of 2-3 × 1012 M&sun;, available at two different resolutions. The resulting galaxies are presented in the companion paper of Murante et al. We find that the GA galaxy has a bar of length 8.8 kpc, present at the two resolution levels even though with a slightly different strength. Classical bar signatures (e.g. pattern of streaming motions, high m = 2 Fourier mode with roughly constant phase) are consistently found at both resolutions. Though a close encounter with a merging satellite at z ˜ 0.6 (mass ratio 1: 50) causes a strong, transient spiral pattern and some heating of the disc, we find that bar instability is due to secular process, caused by a low Toomre parameter Q ≲ 1 due to accumulation of mass in the disc. The AqC galaxy has a slightly different history: it suffers a similar tidal disturbance due to a merging satellite at z ˜ 0.5 but with a mass ratio of 1: 32, that triggers a bar in the high-resolution simulation, while at low resolution the merging is found to take place at a later time, so that both secular evolution and merging are plausible triggers for bar instability

Topics: Formation - galaxies, Kinematics and dynamics - galaxies, Methods, numerical - galaxies, Structure, Space and Planetary Science, Astronomy and Astrophysics
Year: 2014
DOI identifier: 10.1093/mnras
OAI identifier: oai:arts.units.it:11368/2836153
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