Gravitational waves and axion stars from strings

• Edward Hardy (University of Oxford)

Room: Auditorium C.1 Axions are a well-motivated candidate for new physics. If the associated Peccei-Quinn symmetry was ever restored after inflation, cosmic strings form and inevitably produce a contribution to the stochastic gravitational wave background. I will discuss the resulting gravitational wave spectrum combining effective field theory with numerical simulations. Additionally, the axions produced by strings form (at least a component of) dark matter. I will argue that such axion dark matter has interesting substructure, in particular forming solitonic “axion stars”, which lead to possible observational and experimental signals.

Primordial Black Holes and the Early Universe

• Jessica Turner

Room: Auditorium C.1 Primordial black holes, which could have formed after inflation, can have significant implications for the history of the early Universe. Such a population of black holes, which may have differing mass and spin, can undergo evaporation due to Hawking radiation at different points in time. In this talk, I will review the potential impact of this evaporation on various cosmological observables, including the creation of matter-antimatter asymmetry, dark radiation, gravitational waves and dark matter.

Line-Intensity Mapping: opportunities, challenges and new windows for new physics

• José Luis Bernal

Room: Auditorium C.1 Line-Intensity mapping (LIM) uses the integrated flux along the line of sight with relatively low-aperture telescopes, recovering radial information targeting known spectral lines discarding the continuum emission. Mapping the intensity fluctuations of an array of lines from HI 21cm to optical-UV lines offers a unique opportunity to probe redshifts well beyond the reach of other cosmological observations, access regimes that cannot be explored otherwise, and exploit the enormous potential of cross-correlations with other measurements. This promises to open new windows to probe new physics and deepen our understanding of the main unknowns of the Universe. In this talk I will cover the current status of LIM, current experiments and discuss the main challenges to fulfill its promise, and will mention the potential that it holds for probing physics beyond the standard model in the future.