Sebastiaan L. Zoutendijk

Sebastiaan L. Zoutendijk

observational cosmologist

Languages/talen: EnglishNederlands

Quick links: public talkcontact informationshort cv on orcidcode on GitHub

About me

I am a phd candidate at Leiden Observatory, Leiden University, where I do astronomical research and assist in the teaching programme. My field of study is called observational cosmology: the study of the origin, evolution, and properties of the Universe by interpreting what we can see with telescopes. I am studying ultra-faint dwarf galaxies, which are very small galaxies neighbouring our own Milky Way Galaxy.

Eridanus 2
An image of Eridanus 2 from the MUSE-Faint survey, made with muse on the Very Large Telescope in Chile. By measuring how fast the stars in this ultra-faint dwarf galaxy are moving I can study the properties of dark matter.

These ultra-faint dwarfs contain a lot of dark matter. This dark matter constitutes a large fraction of our Universe, yet we know very little about it. With my research I try to learn how much dark matter is in these galaxies and how it is distributed. This could provide additional hints to the nature of dark matter.

Studying dark matter is not straight-forward, because it does not shine like stars and hot gas. This is why it was named dark matter when it was discovered. Though invisible, we can still ‘see’ there is dark matter because it makes galaxies heavier. Like normal matter, dark matter creates gravity. This extra gravity makes all matter in these galaxies moving faster. Therefore, we can study dark matter by measuring the velocities of the stars.

The observations of the ultra-faint dwarfs come from the MUSE-Faint survey. This is a set of observations that are done with an instrument called muse, mounted on the Very Large Telescope at Paranal Observatory in Chile. The instrument takes pictures with a resolution of less than 0.1 megapixel, but each pixel contains 3721 colours. For comparison, a typical smartphone camera has on the order of 10 megapixels, but only uses three colours. Because we have so many colours, we can detect the slight change in colour that moving objects undergo due to the Doppler effect, and we can do this simultaneously for all the stars in our image.

Before starting a phd I studied the bachelor’s programmes Physics and Astronomy and the master’s programme Astronomy and Cosmology, all at Leiden University. In my master’s thesis I looked at how light rays are bent around massive galaxies under the influence of gravity, an effect predicted by Einstein’s Theory of General Relativity. I have tested an alternative approach to analyse the measurements, which might lead to more precise mass estimates of the galaxies bending the light rays. This method is another way to study dark matter in galaxies and works better for heavier galaxies. I have also done a research project to determine the temperature and density of very cold gas in a nearby galaxy using data from a radio telescope array. For my bachelor’s thesis I experimented in an astrophysical laboratory to test if a certain molecule exists in space.

If you want to know more about my research, you can contact me. I also keep a short cv on my orcid profile. A full cv is available on request. If you are looking for open-source code, have a look at my GitHub profile.

Public talk

You can watch me talk about my research. I gave a presentation at Astronomy on Tap Leiden about why we look for dark matter in the smallest galaxies and how we do that.

Contact information

Feel free to contact me if you want to know more, or if you have comments on this home-page!

Sebastiaan L. Zoutendijk

PhD candidate
Leiden Observatory
Leiden University
Visiting address
Niels Bohrweg 2
2333 ca  leiden
Postal address
Postbus 9513
2300 ra  leiden