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The structure and kinematics of the Milky Way disk in a view of a semi-analytic chemo-dynamic model

Sysoliatina, Kseniia

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Abstract

In this work we study the spatial structure as well as the chemical and kinematic properties of the Milky Way disk on the basis of a semi-analytic chemo-dynamical model from Just and Jahreiß (2010) (JJ model). Assuming inside-out formation and a constant thickness of the MW disk, we generalise the local JJ model to Galactocentric distances of R = 4-12 kpc. At each radius we assume a star formation rate (SFR) with a peak shifting to younger ages for the outer disk and use the four-slope broken power-law initial mass function (IMF) from Rybizki and Just (2015). The age-velocity dispersion and age-metallicity relations (AVR and AMR) are then obtained self-consistently; the latter is constrained by metallicity distributions of the Red Clump stars from the Apache Point Observatory Galactic Evolution Experiment (APOGEE, Eisenstein et al., 2011). Within a forward modelling framework, we validate the local JJ model in the solar cylinder by testing it against the samples from the Radial Velocity Experiment (RAVE, Steinmetz et al., 2006) and the first and second Gaia data releases (DR1 and DR2, Lindegren et al., 2016; Gaia Collaboration et al., 2018). We find an overall mismatch in star counts up to ~9%, with a statistically significant discrepancy identified for the dynamically cold populations. We also develop a new treatment of the asymmetric drift and apply it in three metallicity bins to the RAVE local sample and G-dwarfs from the Sloan Extension for Galactic Understanding and Exploration (SEGUE, Yanny et al., 2009). The tangential component of the solar peculiar motion obtained from the RAVE sample is V = 4.47 ± 0.8 km/s. The rotation curve reconstructed from the SEGUE G-dwarfs in a range of distances R = 7-10 kpc has a near-zero slope of 0.033 ± 0.034. The thick disk G-dwarfs are found to be kinematically homogeneous with a scale length of 2.05 ± 0.22 kpc, which is in agreement with values from the literature.

Item Type: Dissertation
Supervisor: Just, appl. Prof. Dr. Andreas
Date of thesis defense: 21 November 2018
Date Deposited: 06 Dec 2018 13:26
Date: 2018
Faculties / Institutes: The Faculty of Physics and Astronomy > Dekanat der Fakultät für Physik und Astronomie
Subjects: 520 Astronomy and allied sciences
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