Projekt B

Gas Flows around High-Redshift Galaxies

Prof. Dr. Lutz Wisotzki (AIP, advisor) and Prof. Dr. Philipp Richter (UP, co-advisor)



Background: Outflows driven by supernovae and nuclear activity are essential processes in the formation and evolution of galaxies. However, observing such outflows in emission is extremely difficult, especially at high redshifts. Arguably the most sensitive approach is to detect this tenuous gas in absorption against bright background sources and relate the absorption signal to galaxies in the line of sight [7][8].

Aims: We will measure the spatial extent of the circumgalactic medium around low-mass galaxies at high redshifts, which are expected to be the main sources for the metal enrichment of the intergalactic medium. To achieve this we will combine high-quality quasar spectra [2] with emission-line diagnostics using the revolutionary MUSE instrument [9]. We will be able, for the first time, to study the enrichment efficiency of galactic outflows at redshifts z > 3 as a function of galaxy properties, for various ionic species. As a by-product, the direct Ly-α emission of potential quasar outflows can also be investigated [10].

Methods: The full setup of the experiment involves three components: (1) locating the emission line objects near the line of sight towards a known quasar, (2) measuring column densities and wavelength shifts of absorption lines in the quasar spectra as a function of impact parameter, and (3) comparing these measurements with the predictions of numerical simulations of galaxy formation. The data will be obtained in the course of the »Guaranteed Time« observations allotted to AIP. The doctoral student will be primarily engaged in the observational side of the project and perform the cross-matching of absorption and emission signals, which is the key »quantitative spectroscopy« element in this endeavour. In contrast to existing studies, MUSE will be so sensitive that essentially every absorber should have a corresponding line emitter, and vice versa. The student will explore various ways to perform a physically meaningful and statistically optimal cross-matching.