Formation of Exponential Profiles from Stellar Scattering Investigated with N-body Simulations
Abstract
The exponential shape of radial surface brightness profiles of disk galaxies has been observed and known for decades. However, the physical mechanism of its formation is not well understood. Disturbances from bars and spiral arms, viscous accretion of gas, and interaction with surrounding galaxies can account for an exponential disk, but these existing theories all have limitations. Experiments with the N-body simulation code GADGET-2 show that exponential profiles can form out of various initial stellar density distributions in a disk containing massive scattering centers, which in a real galaxy can be massive clouds or stellar clusters. The timescale of the profile evolution is influenced by scattering center properties including mass, orbital radius, and spatial number density. Cold disks with local gravitational instabilities can trigger temporary phase mixing and violent relaxation, which accelerate profile changes towards an exponential. This may be responsible for fast establishment of exponential profiles in disturbed dwarf galaxies.
- Publication:
-
AAS/Division of Dynamical Astronomy Meeting
- Pub Date:
- June 2019
- Bibcode:
- 2019DDA....50P...5W