Astronomy Seminar: 2. N-body Simulations of the Formation of Exponential Surface Profiles in Galaxy Disks

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Date/Time:Friday, 06 Dec 2019 from 4:35 pm to 5:25 pm
Location:Physics 38
Contact:Curt Struck
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Jian Wu, ISU

The exponential law of radial surface-brightness profiles in disk galaxies, and some types of dwarf
galaxies has long been observed, but recently has been pursued to very low surface brightness levels.
Current dynamical theories on accretion of viscous gas, secular disturbances from bars, radial migration
due to spiral arms, and interaction with satellite galaxies cast light on the physics behind the formation
of an exponential profile. However, none of these theories are capable of completely explaining the
ubiquity of exponentials across various galaxy types. N-body simulations with Gadget-2 code provide
another way to study exponential profiles. The gravitational attraction of massive clumps, which
represent giant clouds or stellar clusters (especially in young disks), scatter stars and alter stellar density
profiles from different initial shapes towards exponentials. The timescale of the
evolution correlates with local gravitational stability of the stellar disk and is sensitive to the masses of
individual scattering centers.