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Research profile dr. J. (John) McKean

Kapteyn Astronomical Institute

Description of research:

Our Universe contains a rich tapestry of structure that has evolved over cosmic time to form the beautiful canvas of stars, galaxies and clusters of galaxies that we observe in the night sky. However, what we see does not reveal the full extent of our Universe because the dominant form of matter is not the baryonic material that makes up the tangible world around us, but is an unknown form of dark matter.

My research programme is focused on understanding the structure of galaxies and dark matter using a technique called “gravitational lensing”, where the foreground matter in the Universe distorts and magnifies distant galaxies much in the same way that an optical lens distorts light. By studying these distortions, I am able to infer the properties of dark matter and investigate its effect on galaxy formation and evolution.

This work involves making precise measurements of the Universe at the highest possible angular resolution, which for me, means combining many radio telescopes together to form an interferometer with milli-seconds of arc spatial-scales. This in itself is a complex data issue, since combining telescopes from all over the planet (and sometimes beyond) requires sophisticated data analysis techniques to extract the highest quality science information. In addition, the large Terabyte datasets expand our view of “big data” science challenges, and leads to new developments in parallel data storage and processing.

As a tenure-track staff member at the Kapteyn Astronomical Institute and a tenured staff astronomer at the Netherlands Institute for Radio Astronomy (ASTRON), I combine both worlds to develop calibration and imaging strategies for radio telescopes (primarily LOFAR, the Low Frequency Array), whilst spearheading a world leading programme in gravitational lensing at radio wavelengths. The data processing side involves understanding the instrumental response of our radio telescopes to the sky surface brightness distribution and using the data to removes these effects. In particular, I am working on new methods for de-convolving our imaging data to obtain the highest quality science images, while removing spurious imaging artefacts that can lead to the misidentification of structure in the radio sky. My group at the Kapteyn Astronomical Institute is trying to take advantage of these calibration and imaging methods to study galaxy formation at the highest redshifts, but on the smallest-scales through combining the high angular resolution of radio interferometers and the magnifying power of gravitational lensing.

Of course, much of this work is in preparation for the Square Kilometre Array (SKA), the next generation radio telescope to be built South Africa and Australia. The sheer size of the SKA means having a collecting area that improves our sensitivity by over an order of magnitude from where we are now, whist also providing an increase is angular resolution and frequency information. Over the next few years, and within the DSSC framework, I aim to expand our efforts to understand data calibration and image processing on a much larger scale, so that we are fully prepared to take advantage of the SKA when it starts science observations in early 2020. I look forward to collaborating with the researchers within the DSSC to achieve this goal.

key words: Radio astronomy; Gravitational lensing; AGN and star formation

Websites:
Employee (corporate homepage): http://www.rug.nl/staff/j.p.mckean/
Group website: http://www.rug.nl/research/kapteyn/

Last modified:14 February 2018 10.40 a.m.