Aumer, M;
Binney, J;
Schönrich, R;
(2017)
Migration and kinematics in growing disc galaxies with thin and thick discs.
Monthly Notices of the Royal Astronomical Society
, 470
(3)
pp. 3685-3706.
10.1093/MNRAS/STX1483.
Preview |
Text
Schoenrich stx1483.pdf - Published Version Download (5MB) | Preview |
Abstract
We analyse disc heating and radial migration in N-body models of growing disc galaxies with thick and thin discs. Similar to thin-disc-only models, galaxies with appropriate non-axisymmetric structures reproduce observational constraints on radial disc heating in and migration to the Solar Neighbourhood (Snhd). The presence of thick discs can suppress non-axisymmetries and thus higher baryonic-to-dark matter fractions are required than in models that only have a thin disc. Models that are baryon dominated to roughly the Solar radius R0 are favoured, in agreement with data for the Milky Way. For inside–out growing discs, today’s thick-disc stars at R0 are dominated by outwards migrators. Whether outwards migrators are vertically hotter than non-migrators depends on the radial gradient of the thick-disc vertical velocity dispersion. There is an effective upper boundary in angular momentum that thick-disc stars born in the centre of a galaxy can reach by migration, which explains the fading of the high [α/Fe] sequence outside R0. Our models compare well to Snhd kinematics from Radial Velocity Survey and Tycho-Gaia Astrometric Solution data. For such comparisons, it is important to take into account the azimuthal variation of kinematics at R ∼ R0 and biases from survey selection functions. The vertical heating of thin-disc stars by giant molecular clouds is only mildly affected by the presence of thick discs. Our models predict higher vertical velocity dispersions for the oldest stars than found in the Snhd age velocity dispersion relation, possibly because of measurement uncertainties or an underestimation of the number of old cold stars in our models.
| Type: | Article |
|---|---|
| Title: | Migration and kinematics in growing disc galaxies with thin and thick discs |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/MNRAS/STX1483 |
| Publisher version: | https://doi.org/10.1093/MNRAS/STX1483 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Methods: numerical, Galaxy: disc, Galaxy: formation, Galaxy: kinematics and dynamics, galaxies: evolution, galaxies: spiral |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10083991 |
Archive Staff Only
 |
View Item |
