Kavli Affiliate: Ulrich Sperhake | Summary:In massive scalar-tensor gravity, core-collapse supernovae are strong sources of scalar-polarized gravitational waves. These can be detectable out to large distance. The dispersive nature of the propagation of waves in the massive scalar field mean the gravitational wave signals are long lived and many such signals can overlap to form […]
Kavli Affiliate: George Efstathiou | First 5 Authors: Harry T. J. Bevins, Stefan Heimersheim, Irene Abril-Cabezas, Anastasia Fialkov, Eloy de Lera Acedo | Summary: The first billion years of cosmic history remains largely unobserved. We demonstrate, using a novel machine learning technique, how combining upper limits on the spatial fluctuations in the 21-cm signal with […]
Kavli Affiliate: Ulrich Sperhake | Summary:We present a generalization of the curative initial data construction derived for equal-mass compact binaries in Helfer it et al (2019 Phys. Rev. D 99 044046; 2022 Class. Quantum Grav. 39 074001) to arbitrary mass ratios. We demonstrate how these improved initial data avoid substantial spurious artifacts in the collision […]
Kavli Affiliate: Anthony Lasenby | Summary:We discuss the challenges of motivating, constructing, and quantizing a canonically normalized inflationary perturbation in spatially curved universes. We show that this has historically proved challenging due to the interaction of nonadiabaticity with spatial curvature. We construct a novel curvature perturbation that is canonically normalized in the sense of its […]
Kavli Affiliate: E. P. S. Shellard | First 5 Authors: Amelia Drew, E. P. S. Shellard, , , | Summary: We implement adaptive mesh refinement (AMR) simulations of global topological strings using the public code, GRChombo. We perform a quantitative investigation of massive radiation from single sinusoidally displaced string configurations, studying a range of string […]
Kavli Affiliate: Martin Haehnelt | First 5 Authors: Harley Katz, Aayush Saxena, Joki Rosdahl, Taysun Kimm, Jeremy Blaizot | Summary: We use the SPHINX$^{20}$ cosmological radiation hydrodynamics simulation to study how Lyman Continuum (LyC) photons escape from galaxies and the observational signatures of this escape. We define two classes of LyC leaker: Bursty Leakers and […]
Kavli Affiliate: Ulrich Sperhake | Summary:Stationary compact astrophysical objects such as black holes and neutron stars behave as classical systems from the gravitational point of view. Their (observable) curvature is everywhere "small". Here we investigate whether mergers of such objects, or other strongly dynamical spacetimes such as collapsing configurations, may probe the strong-curvature regime of […]
Kavli Affiliate: A. C. Davis | Summary:Electroless nickel plating is an established industrial process that provides a robust and relatively low-cost coating suitable for transporting and storing ultracold neutrons (UCN). Using roughness measurements and UCN-storage experiments we characterized UCN guides made from polished aluminum or stainless-steel tubes plated by several vendors. All electroless nickel platings […]
Kavli Affiliate: Richard Hills | Summary:CMB-S4 — the next-generation ground-based cosmic microwave background (CMB) experiment – will significantly advance the sensitivity of CMB measurements and improve our understanding of the origin and evolution of the universe. CMB-S4 will deploy large-aperture telescopes fielding hundreds of thousands of detectors at millimeter wavelengths. We present the baseline optical […]
Kavli Affiliate: Anthony Lasenby | Summary:For conformally invariant gravity theories defined on Riemannian spacetime and having the Schwarzschild–de-Sitter (SdS) metric as a solution in the Einstein gauge, we consider whether one may conformally rescale this solution to obtain flat rotation curves, such as those observed in galaxies, without the need for dark matter. Contrary to […]