Centre-Outskirt Kinematic Misalignment of Each Galaxy Depending on Environments

Leader: Joon Hyeop Lee

Collaborators: Hyunjin Jeong, Mina Pak, Jiwon Chung, Minje Beom, Pratyush Kumar Das

Topic: The kinematic properties of Milky Way analogues

Status: under review by Science Committee

Abstract: In our recent studies (Lee et al. 2019, ApJ, 872, 78; Lee et al. 2020, ApJ, 893, 154), we have discovered observational evidence supporting the coherence between galaxy rotation and the average line-of-sight motion of neighbors, utilizing data from the CALIFA survey. The significance of this coherence reaches up to 3.5σ for each galaxy’s outskirt rotation (at Re < R < 2Re), while being less evident for central rotation (at R < Re). Faint, blue, or kinematically misaligned galaxies exhibit stronger coherence with neighbor motions than bright, red, or kinematically well-aligned galaxies. Furthermore, galaxy pairs demonstrating strong kinematic coherence tend to share similar optical colors. These findings suggest that the centre-outskirt kinematic misalignment of each galaxy can serve as an indicator of recent interactions with a massive neighbor. We propose to systematically investigate such centre-outskirt misalignments of Hector galaxies embedded in various environments, such as fields, filaments, and clusters, to directly trace their recent kinematic histories and the influence of large-scale environments on them.

Needed data products: stellar velocity and stellar mass (out to 2 effective radius of each galaxy)

Publication Date: 30/06/2025 (The project was agreed to be conducted based on the parameters (inner and outer angular momentum vectors) provided by Pratyush. Therefore, the timeline for this study may vary depending on the progress of Pratyush’s PhD project.)