News & Events

Event Information:

• Wed

  14

  Oct

  2015

  Thu

  15

  Oct

  2015

  [ゼミ] Gerhard Hensler

  10:00 am2-404

  Dwarf Galaxies as ideal laboratories to study astrophysical processes
  Gerhard Hensler, University of Vienna

  From the predictions of Cold Dark Matter (CDM) cosmology low-mass DM sub-halos are expected to form at first and to feed the major galaxies hierarchically. Also dwarf galaxies (DGs) should have been formed early in the universe by the assembly of baryonic matter. Because of their morphological appearance DGs have been traditionally classified in analogy to the massive Hubble-type galaxies. Comprehensive and detailed studies of DGs, however, have spotted the existence of a much larger variety and complexity of their substructures as previously expected. Due to their low gravitation DGs are very sensitive to energetic influences by internal processes, like stellar feedback, as well as by environmental influences, exerted e.g. in galaxy groups and clusters. Both effects can account for morphological transitions. This talk will present a sample of wide activities in the Viennese research group of the speaker addressing presently most burning questions on the formation and morphological evolution of DGs from numerical models to observations, as there are:

  - How does star formation occur at low rates?
  - Can starbursts evacuate DGs of their gas by galactic winds, by this transforming irregular to elliptical DG?
  - How uncertain are observationally derived star-formation rates and element abundances in star-forming DGs?
  - Did strong baryonic outflows by means of galactic winds happened to relax their DM profiles from cuspy to cored ones?
  - To what extent does ram pressure by an intergalactic medium strip off the gas from DGs and transform them morphologically? And how should one understand the morphological variety of elliptical DGs in galaxy clusters?
  - What happens to the ram-pressure stripped gas tails?
  - Is the formation of DGs in tidal tails of merger galaxies a viable path in cosmological galaxy formation and what are its consequences for galaxy structure and the CDM picture?