Physical Society Colloquium

Searching for the invisible: how dark forces shape our Universe

Katelin Schutz

Department of Physics
MIT

How different would our Universe look with the addition of extra particles and forces beyond what we know? We already have ample gravitational evidence for at least one invisible new particle that has properties unlike any particle we have previously discovered. It is possible that this dark matter is made of many different kinds of particles that experience forces unlike the ones we are familiar with in day-to-day life. If these forces only act on dark particles, it may be difficult to discover them and learn more about what is happening in this dark sector. However, dark matter and visible matter do interact gravitationally at the very minimum, and this fact alone might be a good reason not to lose hope. If there are dark forces affecting the distribution of dark matter in our Universe, then that distribution will gravitationally affect the visible matter that we can see. I will discuss how the gravitational portal between dark and visible matter can constrain dark matter theories where dark matter can dissipate energy, can scatter with itself (elastically or inelastically), or can be born non-thermally in the moments after the Big Bang. I will demonstrate this constraining power by harnessing synergies between astrophysical systems including the local Milky Way, nearby dwarf galaxies, galaxy clusters, and large scale cosmological structures.