English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The stellar populations in the inner kiloparsecs of the Milky Way (MW) showcomplex kinematical and chemical structures. The origin and evolution of thesestructures is still under debate. Here we study the central region of a fullycosmological hydrodynamical simulation of a disk galaxy that reproduces keyproperties of the inner kiloparsecs of the MW: it has a boxy morphology andshows an overall rotation and dispersion profile in agreement withobservations. We use a clustering algorithm on stellar kinematics to identify anumber of discrete kinematic components: a high- and low-spin disk, a stellarhalo and two bulge components; one fast rotating and one slow-rotating. Wefocus on the two bulge components and show that the slow rotating one isspherically symmetric while the fast rotating component shows a boxy/peanutmorphology. Although the two bulge components are kinematically discretepopulations at present-day, they are both mostly formed over similar timescales, from disk material. We find that stellar particles with lower initialbirth angular momentum (most likely thick disc stars) end up in theslow-rotating low-spin bulge, while stars with higher birth angular momentum(most likely thin disc stars) are found in the high-spin bulge. This has theimportant consequence that a bulge population with a spheroidal morphology doesnot necessarily indicate a merger origin. In fact, we do find that only$\sim2.3$\% of the stars in the bulge components are ex-situ stars brought inby accreted dwarf galaxies early on. We identify these ex-situ stars as theoldest and most metal-poor stars on highly radial orbits with large verticalexcursions from the disk.

Stars behind bars II: A cosmological formation scenario for the Milky Way's central stellar structure