The Contribution of Spiral Arms to the Thick Disk along the Hubble Sequence

Abstract

The first mechanism invoked to explain the existence of the thick disk in the Milky Way Galaxy, were the spiral arms. Up-to-date work summon several other possibilities that together seem to better explain this component of our Galaxy. All these processes must affect differently in distinct types of galaxies, but the contribution of each one has not been straightforward to quantify. In this work, we present a first comprehensive study of the effect of the spiral arms in the formation of thick disks, as going from early to late type disk galaxies, in an attempt to characterize and quantify this specific mechanism in galactic potentials. To this purpose, we perform numerical simulations of test particles in a three-dimensional spiral galaxy potential of normal spiral galaxies (from early to late types). By varying the parameters of the spiral arms we found that the vertical heating of the stellar disk becomes very important in some cases, and strongly depends on the galaxy morphology, pitch angle, arms mass and its pattern speed. The later the galaxy type, the larger is the effect on the disk heating. This study shows that the physical mechanism causing the vertical heating is different from simple resonant excitation. The spiral pattern induce chaotic behavior not linked necessarily to resonances but to direct scattering of disk stars, which leads to an increase of the velocity dispersion. We applied this study to the specific example of the Milky Way Galaxy, for which we have also added an experiment that includes the Galactic bar. From this study we deduce that the effect of spiral arms of a Milky-Way-like potential, on the dynamical vertical heating of the disk is negligible, unlike later galactic potentials for disks.

18 pages, 24 figures, 3 tables. Accepted for publication in ApJ

References in corpus (13)

• A First Constraint on the Thick Disk Scale Length: Differential Radial Abundances in K Giants at Galactocentric Radii 4, 8, and 12 kpc
• Vertical distribution of Galactic disk stars IV - AMR and AVR from clump giants
• Radial and vertical flows induced by galactic spiral arms: likely contributors to our "wobbly Galaxy''
• Re-visiting the relations: Galactic thin disc age-velocity dispersion relation
• Dissecting simulated disc galaxies II: the age-velocity relation
• Stellar Kinematic Constraints on Galactic Structure Models Revisited: Bar and Spiral Arm Resonances
• On the age heterogeneity of the Pleiades, Hyades and Sirius moving groups
• The Kinematics of Thick Disks in Nine External Galaxies
• Constraining dark matter halo profiles and galaxy formation models using spiral arm morphology. I. Method outline
• On the galaxy spiral arms' nature as revealed by rotation frequencies
• Gas and Stellar Motions and Observational Signatures of Co-Rotating Spiral Arms
• Pattern speed of main spiral arms in NGC 2997: Estimate based on very young stellar complexes
• Properties of thick discs formed in clumpy galaxies

Cited by in corpus (12)

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• The most ancient spiral galaxy: a 2.6-Gyr-old disk with a tranquil velocity field
• New insights in the origin and evolution of the old, metal-rich open cluster NGC 6791
• Can ultralight dark matter explain the age-velocity dispersion relation of the Milky Way disc: A revised and improved treatment
• How the bar properties affect the induced spiral structure
• The imprint of arms and bars on rotation curves: in-plane and off-plane
• Dynamics of thick, open spirals in Perlas potentials
• Through Thick and Thin: The Cosmic Evolution of Disk Scale Height
• Signatures of simulated spiral arms on radial actions
• Mapping the Milky Way with Gaia Bp/Rp spectra-IV: the broken and asymmetric density profile of the stellar disk traced by a large sample of red clumps