Matthijs van der Wild

Projects

Automated image processing with LOFAR data

My current activities include the implementation and improvement of an automated data reduction pipeline for radio data, enabling high-resolution very-long baseline interferometry (VLBI). The International LOw-Frequency ARray (LOFAR) Telescope is an interferometer which has radio stations placed across Europe. It provides a wealth of data which enables the detection and imaging of radio sources with high sensitivity and great detail. The calibration of the individual radio stations, however, is technically challenging. As a result, the full LOFAR telescope is still underutilised. My pipeline addresses this with the development of tools that do not rely on human input, and which produce reliable and reproducible results on platforms that are accessible to astronomers. It extends the resolving power of LOFAR from the Dutch stations to the full international array, delivering sub-arcsecond resolution imaging in a way that is scalable, portable and reproducible.

Inflation and quantum geometrodynamics in scalar-tensor theories

I have investigated the behaviour of a general class of scalar-tensor theories of gravity when effects from quantum gravity are relevant. One such extension adds a scalar degree of freedom to the gravitational interaction, which is then called a scalar-tensor theory. Scalar-tensor theories are an extension to the theory of general relativity which add a scalar degree of freedom to the metric tensor to describe the gravitational interaction. Such extensions can be motivated from cosmology, where the energy of the additional field can drive cosmic inflation, and particle physics, where the Standard Model supplies a natural candidate scalar degree of freedom through the Higgs field. I have developed a method to systematically expand the full quantum dynamics of these models around solutions to the classical equations of motion, and how these classical solutions provide a background on which the quantum gravitational perturbations propagate.

I have applied this strategy to inflationary cosmology. In this setup, the gravitational scalar field fulfills the role of the inflaton. I have determined observational signatures from both slow-roll inflation and quantum gravitational corrections in the primordial power spectrum, and have made predictions on the parameters of the models in the event that sufficiently precise data is available. This would allow an entire class of cosmological models to be ruled out if the structure of these signatures is absent from the data.

More information about this can be found in my thesis.