Spatially Resolved Properties of Galaxies with a Kinematically Distinct Core

TL;DR

This study investigates galaxies with kinematically distinct cores, revealing diverse stellar and gaseous kinematic properties and star formation histories, which shed light on their formation and evolution processes.

Contribution

It provides detailed spatially resolved analysis of counter-rotating galaxies, highlighting the variability in their kinematic and stellar population properties based on emission line diagnostics.

Findings

Galaxies show off-centred peaks in stellar velocity dispersion maps.

Gaseous kinematic maps are generally regular and symmetric.

Star formation histories vary, with some galaxies showing inside-out quenching.

Abstract

Aims. Interacting galaxies show unique irregularities in their kinematic structure. By investigating the spatially resolved kinematics and stellar population properties of galaxies that show irregularities, we can paint a detailed picture of the formation and evolutionary processes that took place during its lifetimes. Methods. In this work, we focus on galaxies with a specific kinematic irregularity, a kinematically distinct stellar core (KDC), in particular, counter-rotating galaxies where the core and main body of the galaxy are rotating in opposite directions. We visually identify eleven MaNGA galaxies with a KDC from their stellar kinematics, and investigate their spatially resolved stellar and gaseous kinematic properties, namely the two-dimensional stellar and gaseous velocity and velocity dispersion ({\sigma}) maps. Additionally, we examine the stellar population properties, as well as spatially resolved recent star formation histories using the Dn4000 and H{\delta} gradients. Results. The galaxies display multiple off-centred, symmetrical peaks in the stellar {\sigma} maps. The gaseous velocity and {\sigma} maps display regular properties. The stellar population properties and their respective gradients show differing properties depending on the results of the spatially resolved emission line diagnostics of the galaxies, with some galaxies showing inside-out quenching but others not. The star formation histories also largely differ based on the spatially resolved emission line diagnostics, but most galaxies show indications of recent star formation either in their outskirts or core. Conclusions. We find a distinct difference in kinematic and stellar population properties in galaxies with a counter-rotating stellar core, depending on its classification using spatially resolved emission line diagnostics.