Research profile dr. G.A. (Gijs) Verdoes Kleijn

Description of research:

My astronomical interest is to understand the symbiotic relationship between galaxies and the supermassive black holes at their centers. Already in the very young Universe the growth of stellar mass and the growth of black holes appears closely linked, leading to a tight relationship between black hole mass and dynamical galaxy mass in today's galaxies. At first sight this appears surprising as the black hole mass and its gravitational sphere of influence are puny compared to its host. It is unknown how supermassive black holes form. It is unknown what physical mechanism maintains the balance between growth in stellar mass and growth of the supermassive black hole. A physical understanding of this symbiotic relationship might advance significantly our understanding of both galaxy evolution and also supermassive black hole formation.

Besides this I am involved in various projects exploitingastronomical survey data. These include galaxy cluster studies, searches for gravitational lenses and searches for near-earth objects and other small solar system bodies.

Being a survey astronomer, I have a strong interest in the technical challenge to disentangle the astrophysical from instrumental information in large sets of survey data. I am involved in the following data-intensive missions / instruments:

• Euclid Space Mission, covering 15000 square degrees of extragalactic sky from space. To be launched by the European Space Agency in 2020. Primary science driver is understanding the accelerated expansion of the Universe. I am co-lead of the Organizational Unit External Data, responsible for Euclidizing all external data to be combined with the Euclid mission data.
• Kilo-Degree Survey, imaging 1500 square degrees with exquisite image quality from the European Southern Observatory (ESO) at Paranal in Chile. In operations since October 2011. Primary science driver is dark matter tomography. I am project manager, leading the survey data production team.
• MICADO, the First-Light near-infrared imager and spectrograph for ESO's European Extremely Large Telescope. I am the dataflow lead for the consortium.

The instrumentalist in me says: “Great to have all this data: it will tell me everything about the physical state of my Observatory”. The astronomer in me says: “Great to have all this data: it will tell me everything about the physics of my Universe!” Our team of astronomers and experts in Astronomical Information Technology aims to meet this challenge by building information systems with extreme “backward chaining”. They link all information contained in final products back to the “raw” initial data. Own-developed technology (“WISE technology”) aims at allowing any level in complexity of the route when traversing the network of linked information through arbitrarily large sets of pixel data and associated meta-data. This effort is being pursued within OmegaCEN , the expertise and datacenter for wide-field imaging, for which I am the deputy lead.

Having advanced astro-informatics tools (e.g., neural networks, machine learning techniques, Bayesian statistical optimization, data-driven visualization) take advantage of such information systems appears to me the way forward to achieve an optimal disentangling of astrophysical and instrumental information from large data. I use the word astro-data-scientist for persons with the expertise to bridge the domains of astro-informatics and astronomical information technology.

Websites:
Employee (corporate homepage): http://www.rug.nl/staff/g.a.verdoes.kleijn/
Group website: http://www.rug.nl/research/kapteyn/