Secular Evolution in Disk Galaxies

By J. Sellwood. 2013

217 citations recorded by the source corpus.

Disk galaxies evolve over time through processes that may rearrange both the radial mass profile and the metallicity distribution within the disk. This review of such slow changes is largely, though not entirely, restricted to internally-driven processes that can be distinguished from evolution driven by galaxy interactions. It both describes our current understanding of disk evolution, and identifies areas where more work is needed. Stellar disks are heated through spiral scattering, which increases random motion components in the plane, while molecular clouds redirect some fraction of the random energy into vertical motion. The recently discovered process of radial migration at the corotation resonance of a transient spiral mode does not alter the underlying structure of the disk, since it neither heats the disk nor causes it to spread, but it does have a profound effect on the expected distribution of metallicities among the disk stars. Bars in disks are believed to be major drivers of secular evolution through interactions with the outer disk and with the halo. Once the material that makes up galaxy disks is converted into stars, their overall angular momentum distribution cannot change by much, but that of the gas is generally far more liable to rearrangement, allowing rings and pseudo-bulges to form. While simulations are powerful tools from which we have learned a great deal, those of disks may suffer from collisional relaxation that requires some results to be interpreted with caution.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/72828864df93e04176de61598ffdea3645694cd6

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In Astronomy and Astrophysics

Citations in the corpus

Constraints on Radial Migration in Spiral Galaxies - II. Angular momentum distribution and preferential migration (2018, background): “(12) Such a kinematically warm disc is locally stable but may support global instabilities at all radii (see Sellwood 2014).”
The Coevolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe (2014, background): “Examples of such non-axisymmetric perturbations are bars, oval distortions, and even spiral arms (e.g. Athanassoula 2008, Kormendy & Kennicutt 2004, Sellwood 2014).”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, background): “…structural and kinematic properties that the major part of the Galactic bulge was built from the disk through evolutionary processes similar to those observed in galaxy evolution simulations, as is also inferred for many external galaxies (so-called secular evolution; Kormendy 2013, Sellwood 2014).”