BHI Colloquium


Tuesday, December 3, 2019, 1:30pm


BHI Meeting Room

Xiaohui Fan (University of Arizona)

Title: The First Luminous Quasars

Abstract: I will describe the ongoing surveys to discover luminous quasars at the highest redshift. These surveys allow the first measurements of quasar luminosity function at the epoch of reionization, and predict the redshift at which we will find the earliest luminous quasars powered by billion solar mass black holes in the observable universe. I will also update the effort to measure black hole mass function in quasars at the earliest epoch, and the possibility of directly measure black hole mass through gas dynamics at z>6.


Justin Ripley (Princeton University)

Title: Dynamics of scalarized black holes in a modified gravity theory

Abstract: I report on a numerical investigation of the nonlinear dynamics of scalarized black holes in a modified gravity theory, Einstein dilaton Gauss-Bonnet (EdGB) gravity. One motivation for this study is to understand how classical gravity might differ from the predictions of general relativity in the dynamical strong field regime, as is applicable to the last stages of binary black hole coalescence. EdGB gravity is also an important and representative member of a class of modified gravity theories, Horndeski theories, that have been invoked in attempts to address the discovery of dark matter, dark energy, and resolve the issues of the initial cosmological singularity and singularities formed during gravitational collapse. I discuss how initial data exists for which the equations of motion for the theory can dynamically change character from hyperbolic to elliptic differential equations, after which the theory presumably loses predictive power.