Research
On this page I provide an overview of my scientific research and technical work, mostly in the field of radio astronomy.
Overview
SKA precursor science
The Australian Square Kilometre Array Pathfinder (ASKAP) is a next-generation radio telescope and SKA precursor constructed by CSIRO in the Shire of Murchison in Western Australia. ASKAP is a powerful survey instrument capable of mapping the H Ⅰ emission of galaxies across the entire accessible sky out to redshifts of z ≈ 0.1 for direct detections and z ≈ 1 in stacking experiments.
I am actively involved in three of the H Ⅰ survey science projects on ASKAP and another three projects on MeerKAT, the South African SKA precursor telescope:
Structure and evolution of galaxies
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 halos are expected to form first and later merge and accrete onto larger halos to form more massive galaxies like the Milky Way. Due to its general abundance, widespread distribution and susceptibility to ram pressure, neutral hydrogen (H Ⅰ) is a particularly good tracer of the merging and accretion history of galaxies.
The Magellanic Stream and high-velocity clouds
Our Milky Way is surrounded by a vast population of gas clouds, the so-called high-velocity clouds (HVCs), which 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 gas streams 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
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 parameterisation
The next generation of radio telescopes, including 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 several H Ⅰ survey projects on ASKAP and MeerKAT I have developed source finding and parameterisation algorithms and software.
