William H. Kinney, Nina K. Stein, SUNY)

We consider recently proposed bouncing cosmological models for which the Hubble parameter is periodic in time, but the scale factor grows from one cycle to the next as a mechanism for shedding entropy. Since the scale factor for a flat universe is equivalent to an overall conformal factor, it has been argued that this growth corresponds to a physically irrelevant rescaling, and such bouncing universes can be made perfectly cyclic, extending infinitely into the past and future. We show that any bouncing universe which uses growth of the scale factor to dissipate entropy must necessarily be geodesically past-incomplete, and therefore cannot be truly cyclic in time.

Torben C. Frost

Current astrophysical observations show that on large scale the Universe is electrically neutral. However, locally this may be quite different. Black holes enveloped by a plasma in the presence of a strong magnetic field may have acquired a significant electric charge. We can also expect that some of these charged black holes are moving. Consequently to describe them we need spacetime metrics describing moving black holes. In general relativity such a solution is given by the charged C-de Sitter-metric. In this article we will assume that it can be used to describe moving charged black holes. We will investigate how to observe the electric charge using gravitational lensing. First we will use elliptic integrals and functions to solve the geodesic equations. Then we will derive lens equation, travel time and redshift. We will discuss the impact of the electric charge on these observables and potential limitations for its observation.

Daniel Green, Joel Meyers

The next generation of cosmological surveys are expected to measure a non-zero sum of neutrino masses, even down to the minimum value of 58 meV inferred from neutrino flavor oscillation. The implications of such a measurement for the physics of neutrinos have been well documented; in contrast, the cosmological implications of such a measurement have received less attention. In this paper, we explore the impact of a neutrino mass detection consistent with $\sum m_\nu = 58$ meV for our understanding of the history and contents of the universe. We focus primarily on three key areas: the thermal history of the universe, clustering of matter on diverse scales, and the application to dark matter and dark sectors. First we show that a detection of non-zero neutrino mass would provide a unique connection between the cosmic neutrino background, which is detected gravitationally, and neutrinos measured on Earth. We then discuss how the consistency of a detection between multiple probes will impact our knowledge of structure formation. Finally, we show how these measurements can be interpreted as sub-percent level tests of dark sector physics.