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## July 2020

### Atlantic GR Seminar: Sharmila Gunasekaran Gnanam (MUN) and Robert Santacruz (UNB)

Slow decay of waves in gravitational solitons Sharmila Gunasekaran Gnanam Memorial University of Newfoundland Gravitational solitons are globally stationary horizonless asymptotically flat spacetimes. In this talk, I will describe the methodology used to prove that massless scalar waves in a particular family of soliton spacetimes decay very slowly. The proof involves the construction of quasimodes which are approximate solutions to the wave equation. This slow decay can be attributed to the stable trapping of null geodesics and is suggestive of…

Find out more »## August 2020

### Atlantic GR Seminar: Nicholas Layden (Dalhousie) and Sharmin Akhter (MUN)

Geometric Horizons in the Szekeres Spacetime Nicholas Layden (Dalhousie University) A new conjecture for geometric horizons has been introduced which may provide a potential alternative to using apparent horizons and related surfaces for analyzing the dynamics of black hole spacetimes. In particular, using two examples of black hole formation in a collapsing universe in the Szekeres spacetime, the formation, evolution, and detection of geometric horizons are shown. In addition, a function for detecting apparent horizons in the Szekeres spacetime is…

Find out more »## September 2020

### Atlantic GR Seminar: Kam To Billy Chan (MUN)

The Reissner-Nordstrom Near Horizon Geometry is a Tangent Spacetime The near horizon geometry (NHG) of an extremal Reissner-Nordstrom black hole is obtained in conventional global AdS coordinates and in the coordinates of the parent spacetime. Geometrical objects, specifically Killing vectors and spacetime points, are mapped from the boundary and horizon of the NHG into the parent spacetime coordinates. The outcome is that the NHG is a tangent spacetime to the extremal Reissner-Nordstrom black hole’s degenerate horizon and that the degenerate…

Find out more »## October 2020

### Atlantic GR Seminar: Turkuler Durgut (MUN)

Asymptotically Anti-de Sitter Gravitational Solitons In this talk, I will consider the stability of asymptotically anti-de Sitter gravitational solitons. These are globally stationary, asymptotically (globally) AdS spacetimes with positive energy but without horizons. I will introduce my ongoing project investigating solutions of the linear wave equation in this class of backgrounds. I will provide analytical expressions for the behavior of the scalar field near the soliton bubble and at spatial infinity. The special BPS (supersymmetric) case will then be examined…

Find out more »## November 2020

### Atlantic GR Seminar: Jinzhao Wang (ETH Zurich) and Saikat Mondal (MUN)

Outer entropy equals Bartnik-Bray inner mass, and the gravitational ant conjecture Jinzhao Wang (ETH Zurich) Entropy and energy are found to be closely tied on our quest for quantum gravity. We point out an interesting connection between the recently proposed outer entropy, a coarse-grained entropy defined for a compact spacetime domain motivated by the holographic duality, and the Bartnik-Bray quasilocal mass long known in the mathematics community. In both scenarios, one seeks an optimal spacetime fill-in of a given closed,…

Find out more »## February 2021

### Atlantic GR Seminar: Sarah Muth (MUN)

Marginally Outer Trapped (Open) Surfaces in 4+1 Dimensional Schwarzschild In the case of binary black hole mergers, the surface of most obvious interest, the Event Horizon, is often computationally difficult to locate. Instead, it is useful to turn to quasi-local characterizations of black hole boundaries, such as Marginally Outer Trapped Surfaces (MOTS), which are defined for a single time slice of the spacetime, and the outer-most of which is the apparent horizon. In this talk, I will describe ongoing work…

Find out more »## March 2021

### Atlantic GR Seminar: Dr Robie Hennigar (MUN)

Holographic Complexity and Thermodynamic Volume I will discuss recent work exploring the holographic complexity conjectures for rotating black holes. A relationship between the complexity of formation and the thermodynamic volume of the black hole is found, and I discuss the evidence that suggests this relationship holds generally. This is one of the first connections between thermodynamic volume and holography, and I will discuss possible implications. The Atlantic General Relativity 2020 online postdoc/student seminar series is in the tradition of the…

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