Tim Zimmermann

Constraining the properties of wave-like dark matter
in the presence of baryons

The role of dark matter as essential ingredient to the standard model of cosmology is a seldomly disputed fact in the scientific community. Although a variety of observations provide convincing evidence for its existence, its fundamental character remains largely elusive. The lack of evidence for the correctness of Cold Dark Matter (CDM) - our best effective theory - on sub-galactic scales justifies why alternative dark matter models remain an active field of research.

Within the last decade, ultralight dark matter (ULDM), one potential substitute for CDM, has seen considerable interest in the astrophysics community due to its (i) model simplicity (ii) intriguing wave-like dynamical behaviour and (iii) well motivated theoretical origin. If tuned properly, ULDM produces distinct signatures such as cored DM halos and a suppression, or smoothing, of matter structures on length scales smaller than implied by Heisenberg’s uncertainty principle.

In this project I’m interested in how these signatures behave if we increase the model fidelity by adding baryonic -observable- matter and it’s associated feedback processes into the mix. Questions of interest are: How transient are ULDM structures? What observable effects does ULDM imply if baryons are added? Can we distinguish ULDM-effects from baryon-induced signatures? And of course, can we sharpen existing constraints (or find new bounds) of the ULDM parameter space if we increase the physical fidelity of the model?

Simulating these kind of systems is computationally daunting. It is for this reason that I’m also interested in developing cheap surrogate models for ULDM that may help to understand certain aspects of its phenomenology, say quantised vortices, without simulating ULDM from scratch.