Torsten’s Science

My astronomical research so far has concentrated on one of the oldest questions of modern astronomy: how do galaxies evolve? Are all the seemingly different kinds of galaxies actually the same thing, but seen at different stages of their lifes? Or are their different morphologies imprinted on them by the initial conditions under which they formed?

One specific topic I am interested in is the structure of the (presumably) “simplest” spiral galaxies, i.e. those that appear to consist only of a stellar disk, and show no prominent central bulge. How did these “late-type spirals” form, and how have they avoided the formation of a dynamically hot stellar component which seems to be an unavoidable consequence of galaxy merging?

A related piece of the puzzle is the question of what regulates star formation in galaxy disks, i.e. what are the dynamical processes that govern the inflow of molecular gas into the central regions of spiral galaxies. There, the high gas densities often lead to enhanced star formation. This manifests itself in the presence of very dense stellar clusters in the nuclei of most spirals, as well as in circum-nuclear star formation which - over the life of a galaxy - could potentially result in the build-up of a bulge.

I am an observational astronomer, not a theorist. I am using a combination of imaging and spectroscopy, both at optical and infrared wavelengths, to address these questions. The infrared has the advantage that it is less attenuated by dust, and thus allows a deeper look into the often dust-obscured central regions of galaxies. The tools I use are cameras (MANIAC,WFPC2,NICMOS), long-slit spectrographs (CSHELL,STIS,UVES), and also integral-field units (3D,SINFONI). The latter are “imaging spectrographs” which make it possible to obtain spectra over a contiguous two-dimensional area of the sky in a single integration.