Colloquium on Jun. 18, 2026

IllustrisTNG Insights: Formation Mechanisms of Types and Structures of Galactic Disks

Speaker: Min Du (Xiamen University)

Venue: SWIFAR Building 2111

Time: 16:00 PM, Thursday, Jun. 18, 2026

Abstract:

Using the IllustrisTNG cosmological simulation, this report presents three studies on the types and structures of galactic disks. First, we introduce the formation mechanisms of different disk profile types — single-exponential (Type I), down-bending (Type II), and up-bending (Type III) — showing that Type II breaks arise naturally from inside-out growth, while Type III profiles are linked to mergers and bar-driven dynamical heating. Second, we present Gal3D, a superellipsoid framework for measuring the intrinsic three-dimensional structure of galaxies, revealing how disk flattening, box/peanut bulges, and triaxial components vary with stellar mass and across simulations. Third, we examine the properties of bars in TNG disk galaxies, finding that mergers are the dominant factor suppressing bars in massive galaxies (log M*/M⊙ > 10.8), while dynamically hot disks prevent bar formation in lower-mass systems — and that TNG produces an excess of short bars, indicating insufficient central dynamical perturbation from mergers and gas inflows.