Sjoert van Velzen

Assistant Professor · Leiden Observatory

Lead of the Tidal Disruption Event working group · Vera C. Rubin Observatory

I find stars torn apart by supermassive black holes — and use these flares, and any neutrinos they might produce, to learn how black holes grow.

Sjoert van Velzen

Research

Black holes caught in the act

I search the skies to find stars that happen to pass a bit too close to a supermassive black hole. Due to the strong gravity of the black hole, these unlucky stars get torn apart into streams of gas. The result is a sudden increase of fuel for the black hole, leading to a panchromatic flare of light. With my team of collaborators, we have collected a large sample of these rare and valuable events, and I use them to learn about the origin of black holes in the early Universe.

A second strand of my work follows high-energy neutrinos — ghostly particles that race across the Universe almost unhindered. We recently found that some of them can be produced when massive black holes feed, perhaps also during tidal disruption events. With the KM3NeT neutrino telescope and wide-field optical surveys, my group hunts for the cosmic sources of these elusive particles.

Group

Group members

Postdocs & PhD students

JN
Jannis Necker
Postdoc
IR flare selection; Rubin & neutrino follow-up
VA
Vysakh P. Anilkumar
PhD student, 2024–
Photometric classification of TDEs
LP
Lucas Pouw
PhD student (joint with Elena Rossi), 2025–
Multi-messenger galactic nuclei
LV
Luc Voorend
PhD student, 2025–
High-energy neutrinos with KM3NeT
JS
Jingbo Sun
PhD student (visiting), 2025–
TDEs & AGN variability for Rubin

Former member: Niccolò Veronesi (PhD, joint with Elena Rossi) — now postdoc at ISTA, Austria.

MSc students

YearNameThesis project
2026Nikolaos Ladopouloscurrent
2026Garrett Coeycurrent
2025Emory MurffSearching for black holes with quasi-periodic eruptions (current)
2025Xueyang HuBlack-hole masses from late-time emission of tidal disruption events
2025Britt OttevangerPhotometric classification of nuclear transients with machine learning
2025Liam de VosTidal disruption event rates vs. central stellar density and star-formation history
2024Lucas PouwViewing-angle constraints for stellar tidal disruption events
2024Tim van der VuurstPhotometric population study of ZTF nuclear transients
2023Remon van GaalenAnalysing tidal disruption event dust echoes
2023Claire Olde LoohuisWhere do compact galaxies live?
2022Thomas BoxmanStatistical significance of high-energy neutrinos from black holes (KM3NeT)
2021Tian LiHubble Space Telescope observations of post-starburst galaxies
2021Daming YangHost galaxies and spectral types of tidal disruption flares
2021Ashmara WederfoortRadio observations of stellar tidal disruption flares

Publications

Links to publications

Media

Selection of press coverage

Contact

Get in touch

Email
[first name] @strw.LeidenUniv.nl
Address
Leiden Observatory
Einsteinweg 55
2333 CC Leiden, The Netherlands
Find me
Github · ADS · arXiv · Google Scholar