Website of Tobias Westmeier



SKA precursor science

One of the phased-array feeds developed for ASKAP The Australian Square Kilometre Array Pathfinder (ASKAP) is a next-​ge­ner­ation radio telescope and SKA precursor currently being constructed by CSIRO in the Murchison region of Western Australia. Once completed, ASKAP will be a powerful survey instrument capable of mapping the H i emission of galaxies across the entire sky and out to redshifts in excess of 0.2.

I am actively involved in three of the H i survey science projects on ASKAP and two projects on MeerKAT, the South African SKA precursor telescope:

Structure and evolution of galaxies

Combined optical and HI image of NGC 300 If we believe in the ΛCDM paradigm, then structure in the universe should have evolved in a hierarchical manner. In this scenario, small dark-matter haloes are expected to form first and later merge and accrete onto larger haloes to form more massive galaxies like the Milky Way. Due to its general abundance, widespread distribution, and susceptibility to ram pressure, neutral hydrogen is a particularly good tracer of the merging and accretion history of galaxies.

The Magellanic Stream and high-velocity clouds

All-sky map of high-velocity clouds Our Milky Way is surrounded by a vast population of gas clouds, called high-velocity clouds (HVCs), that are mainly detectable in H i emission. The most famous HVC complex of the Milky Way is the Magellanic Stream, thought to be a system of tidal arms originating from the Magellanic Clouds. My main research interests are in the study of the extended filaments of the Magellanic Stream as well as the search for HVC populations around other, nearby galaxies, in particular the Andromeda galaxy.

Probing halo gas through Ca ii and Na i absorption

High-velocity Na I absorption lines During the last decades, absorption and emission line measurements have demonstrated that the Milky Way is surrounded by a complex, multi-phase gaseous halo. Embedded in a corona of million-degree gas, neutral and ionised gas clouds move with high radial velocities through the Milky Way halo, giving rise to the population of IVCs and HVCs.

Source finding and parametrisation

Source finding example The next generation of radio telescopes, such as the Square Kilometre Array (SKA), will produce unprecedented quantities of data that cannot be inspected by eye any longer. Instead, fully automated pipelines will be required to detect and analyse sources. As part of my contribution to the WALLABY and DINGO projects on ASKAP I am actively involved in developing and testing automated source finding and parametrisation algorithms.


© 2020 Tobias Westmeier
Contact | Last modified: 2 October 2020