The large-scale structure of our Universe is well described by a model in which matter is predominantly Cold Dark Matter (CDM). While CDM was initially thought to have trouble reproducing observations of dwarf galaxies, it has generally become accepted in the last decade that a proper treatment of the gas and stars (baryonic matter) can alleviate those tensions. However, the models of energetic "feedback" from stars that have solved some of the tensions in CDM are now running into trouble solving new problems, specifically the "diversity of rotation curves" problem. The diversity of rotation curves has led to renewed interest in self-interacting dark matter (SIDM) to explain observations. In this talk, I will present a new suite of simulations, the Marvelous Massive Dwarfs, that is the first to recover a broad range of diversity in rotation curves in CDM. I show that these simulations also seem to better reproduce the sizes and morphologies of dwarf galaxies, and discuss why. I will highlight predictions from this new suite that can help us disentangle baryonic effects and learn about dark matter.

Speaker: Alyson Brooks (Rutgers University)

The 2025 Fall Colloquium talks are held on Wednesdays at 3:00 PM. This colloquium is hosted by STScI and will be held as an in-person and virtual event.

You may join in person at STScI’s John N. Bahcall Auditorium or virtually on the STScI Research YouTube channel.

Please direct questions or comments to contact above. The 2025 Fall Colloquium Committee members are: Nimisha Kumari (STScI), Elena Manjavacas (STScI), Jack Neustadt (JHU), Kevin Schlaufman (JHU), Adam Smercina (STScI), Ethan Vishniac (JHU).