BHI Colloquium


Tuesday, November 19, 2019, 1:30pm to 2:30pm


BHI Meeting Room

Andreas Bauswein (University of Heidelberg)

Title: The QCD phase transition in neutron star mergers

Abstract: At low temperature quantum chromodynamics predicts a transition from ordinary hadronic matter to de-confined quark matter at higher densities. Whether or not this transition occurs at densities which are realized in neutron stars is currently unclear. We discuss an unambiguous signature of this phase transition in neutron star mergers. This idea is based on a comparison between information from the gravitational-wave inspiral signal and the emission from the post-merger phase. Since densities increase during merging, the post-merger phase represents an ideal probe of high-density matter physics and can be employed to set constraints on the transition to de-confined quark matter.

Anna Ogorzalek (NASA GSFC/UMD)

Title: Uncovering the physics behind AGN feedback with high resolution X-ray spectroscopy

Abstract: Active galactic nuclei (AGN) significantly impact the evolution of their host galaxies, as they can prevent star formation by either expelling large fractions of gas with wide-angle outflows, or heating up the halo gas with jets. However, how the AGN energy is transferred to the galaxy remains unknown. The X-ray band is key to answering this question, as the gas immediately impacted by the black hole reaches high, X-ray emitting temperatures. In this talk, I will present new applications of modern statistical techniques to high resolution X-ray spectra of nearby AGN in Seyferts, elliptical galaxies, and galaxy clusters. Here, using Bayesian approaches allows us to place competitive constraints on gas kinematics and thermodynamics, and gain new insights into the physical processes behind AGN feedback.

Vasudev Shyam (Perimeter Institute)

Title: Holography at finite radius

Abstract: The theoretical setting which thoroughly realizes the holographic principle is the AdS/CFT correspondence. It equates quantum gravity in Anti de Sitter (AdS) space to a non gravitational conformal field theory (CFT) living on its asymptotic boundary. I will describe recent efforts to generalize this correspondence to the setting where the boundary is situated at a finite distance from any point in the interior of the AdS spacetime. This scenario serves as a prototype for understanding quantum gravity in finite spacetime volumes via holography.
In three spacetime dimensions, the theory living on such a finite boundary is conjectured to be a quantum field theory arising from a special irrelevant operator deformation of the conformal field theory that would have inhabited the asymptotic boundary. In this setting I will show that the so called holographic entanglement entropy conjectures, which point to a deep connection between spacetime geometry and quantum information theory, continue to hold.