Abstract: I will present a few recent results involving compact objects and dark matter:
1. We consider a new renormalizable Yukawa interaction in the Friedberg-Lee-Sirlin Q-ball Lagrangian and show that it destabilizes the Q-ball at large charge Q. These unstable Q-balls exhibit a paradoxical growth behavior, leading to possible cosmological consequences.
2. Resonant leptogenesis provides a mechanism for generating the baryon asymmetry of the Universe with TeV scale right-handed neutrinos, but requires at least two nearly degenerate right-handed neutrinos. We consider resonant leptogenesis occurring in the false vacuum of a first order phase transition, which helps ease the fine-tuning problem and can result in a hierarchical mass texture in the true vacuum.
3. Many pathways to sterile (right-handed) neutrino production have been proposed, each generating a distinct spectrum. We consider multi-modal distributions of sterile neutrinos produced by a combination of different processes. These mixed populations could have both CDM and WDM components, potentially influencing small-scale structure formation.
4. Extremely light PBHs have correspondingly short lifetimes, evaporating before the era of Big Bang Nucleosynthesis and leaving few traces of their existence. We show that if light PBHs are formed with sufficient density to matter-dominate the Universe, they can cluster and form larger and longer-lived PBHs. These PBHs could be currently emitting high-energy Hawking radiation along with a coincident gravitational wave background signal.
