Milky Way-like galaxies: Stellar population properties of dynamically defined disks, bulges and stellar haloes

SARA ORTEGA- MARTINEZ; AURA OBREJA; R DOMINGUEZ-TENREIRO; PEDROSA, S.; ROSAS-GUEVARA, Y.; P TISSERA

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2022

0035-8711

The formation of galaxies can be understood in terms of the assembly patterns of each type of galactic component. To perform thiskind of analysis, is necessary to define some criteria to separate those components. Decomposition methods based on dynamicalproperties are more physically motivated than photometry-based ones. We use the unsupervised Gaussian Mixture model ofgalactic structure finder to extract the components of a sub-sample of galaxies with Milky Way-like masses from theEAGLE simulations. A clustering in the space of first and second order dynamical moments of all identified substructuresreveals five types of galaxy components: thin and thick disks, stellar halos, bulges and spheroids. We analyse the dynamical,morphological and stellar population properties of these five component types, exploring to what extent these properties correlatewith each other, and how much they depend on the total galaxy stellar and dark matter halo masses. All galaxies contain a bulge,a stellar halo and a disk. 60% of objects host two disks (thin and thick), and 68% host also a spheroid. The dynamical diskto-total ratio does not depend on stellar mass, but the median rotational velocities of the two disks do. Thin disks are wellseparated in stellar ages, [Fe/H] and 𝛼-enhancement from the three dispersion-dominated components, while thick disks are inbetween. Except for thin disks, all components show correlations among their stellar population properties: older ages meanlower metallicities and larger 𝛼-enhancement. Finally, we quantify the weak dependence of stellar population properties on eachcomponent’s dynamics.