Final presentation topics - adam-coogan/GRAPPA_Student_Seminar_2019 GitHub Wiki

  1. GeV excess. The galactic center GeV excess is an excess of gamma-rays coming from the center of the Milky Way. What are the challenges in understanding the source of this excess? Could this be produced by dark matter, or is a different explanation more plausible?
  2. Primordial black holes. Explain what primordial black holes are, and evaluate whether they could be dark matter. How could they be detected? Is it possible that they only constitute a subdominant fraction of dark matter?
  3. Dwarf spheroidal galaxies. Dwarf spheroidal galaxies are excellent targets for searches for dark matter annihilation and decay signals. Why is this the case? How do we know about the dark matter content of these objects? What are the simplest methods to estimate the dark matter content and the so-called “J-factor” describing the strength of the dark matter signal? What complicating factors could affect these simple estimates?
  4. Warm versus cold dark matter. Cold dark matter models predict the existence of dark matter halos down to very small masses, much smaller than the smallest dark matter supported galaxies that we actually observe (dwarf spheroidal galaxies). In warm dark matter scenarios these structures would be erased. Why is this the case? What constraints exist on the temperature of dark matter (often expressed in terms of the free-streaming scale, or in terms of the mass of a thermal relic)? How does structure formation proceed throughout the universe’s history with cold versus warm dark matter?
  5. Dark matter subhalos. Structures like the Milky Way halo are made of smaller substructures. How much do we know the properties of these subhalos, both observationally and theoretically? Presence of subhalos is particularly important for indirect dark matter searches through, e.g., gamma rays. What is the current status of this line of research?
  6. Sterile neutrinos. Sterile neutrinos with keV mass are considered to be a good dark matter candidate. What motivates this and what is their production mechanism in the early Universe? How can we detect them through observations?
  7. Axion dark matter. The axion is an excellent dark matter candidate with natural motivation from issues with the Standard Model with very low mass. What problem was the axion proposed to solve? Given that it is so light, why is it cold rather than hot dark matter? What methods have been used and proposed to constrain axion dark matter?
  8. Dark matter production mechanisms. While it is the most standard dark matter production mechanism, freeze out is only one of many ways to obtain the correct relic abundance. For example, a completely different mechanism sets the axion relic abundance. Survey some of these scenarios, and explain their motivations and signatures. (Some ideas to get you started: strongly-interacting massive particles, WIMPzillas, FIMPs, ELDERs, …)