Join us for Cosmolunch! This week we will have a follow-up Q&A session with our presenters from last week, Linda Xu (Harvard) and Dustin Madison (West Virginia).
Speaker: Linda Xu (Harvard)
Title: Cosmological Measurements of Massive Light Relics
Abstract: An intriguing possibility for the particle makeup of the dark sector posits the existence of light, feebly interacting particles that constitute a fraction of the observed dark matter abundance. These types of light relics arise ubiquitously in particle theories, and detection prospects are surprisingly optimistic when leveraging cosmological datasets. In this talk I discuss the impact of these new particle species on observables, the CMB and LSS in particular, and the power of near-future galaxy surveys to detect or constrain them.
Speaker: Dustin Madison (West Virginia)
Title: Gravitational Wave Memory and the Cosmic Microwave Background
Abstract: Gravitational waves (GWs) leave in their wake permanent residual distortions of space referred to as “memory.” Memory accumulates over the entire history of gravitationally radiating systems, but it grows especially rapidly during bright GW events like binary black hole mergers. From an observational perspective, such GW bursts with memory (BWMs) generate long-lasting redshifts and permanent angular deflections in distant sources of light. Unlike purely transient GW events, observational signatures of BWMs can superpose and reinforce one another over cosmological time scales, leading to ever-larger perturbations to the appearance of more distant sources of light. The largest possible manifestation of this cumulative signature of memory, built up over nearly the entire history of the Universe, will like in the cosmic microwave background (CMB). I will discuss some of my recent efforts to understand these imprints of GW memory in the CMB and future work to describe the ultimate character and detectability of this signature of memory.