Hi! I'm Ewoud Wempe, a postdoctoral researcher specializing in Near-Field Cosmology.
I am developing a new suite of constrained Local Group simulations at LIRA at the Observatoire de Paris. Previously, I completed my PhD thesis at the Kapteyn Institute in Groningen.
Local Group simulations
In Wempe et al (2024), I have created a statistically fair sample of constrained Local Group simulations. See a few examples below:
The mass distribution in and around the Local Group
In Wempe et al. (2026), published in Nature Astronomy, we show that the Local Group's mass can be reconciled with its surrounding velocity field in ΛCDM, but this requires that the surrounding mass distribution is strongly flattened into a sheet. The inferred sheet extends to at least 10 Mpc, with deep voids above and below it. This mirrors known structures in the distribution of galaxies such as the Local Sheet and Local Void.
The formation of the Local Group inside the Local Sheet
This video tracks the origin of particles ending up in the Milky Way subhalo (red, on the left), and ending up in the Andromeda subhalo (blue, on the right), in coordinates rotated and scaled such that the MW is at (0,0,0) and M31 is at (1,0,0). This is a 'stack' of 70 simulations, showing the posterior mean. Note that the material first collapses along the z'-axis, and after that most accretion occurs within the sheet. For more information, check out Wempe et al (2025)!
About Me
In my free time I like to play piano, play chess, bake my own bread, go for a run, and I have a love for mountains and all kinds of things mountain-related (hiking, climbing, snowboarding).
Contact
Please email me at ewoudwempe a abcg.examplemail.com