The 35th Midwest Relativity Meeting & Eric Fest

Session

Saturday Afternoon Session 1

1 Nov 2025, 14:00

113 (MacKinnon Building)

59. Blue Apple Award

01/11/2025, 14:00

34. Initial data of slow fall off

David Garfinkle (Oakland University)

01/11/2025, 14:05

The usual definition of asymptotic flatness at spatial infinity requires that the flat metric be approached at a particular rate. However, slower rates of fall off are compatible with well-defined evolution under the Einstein vacuum equations. Since initial data must satisfy the constraint equations, we want to know if we can specify the fall off rate that we want and still have...

55. Asymptotically Euclidean Solutions of the Constraint Equations with Prescribed Asymptotics

James Wheeler (University of Michigan)

01/11/2025, 14:20

I will discuss ongoing work on the construction of asymptotically flat vacuum initial data sets in General Relativity via the conformal method. My collaborators and I have demonstrated that certain asymptotic structures may be prescribed a priori through the method's seed data, including the ADM momentum components, the leading- and next-to-leading-order decay rates, and anisotropy in the...

5. A “dictionary” to test GR with GW: from observations to theory

Suvendu Giri (Uppsala University, Sweden)

01/11/2025, 14:35

GR, while one of the most successful and well-tested theories to date, is expected to receive corrections at high energies—through higher-curvature terms, additional degrees of freedom, or both. Given the vast landscape of possible extensions, how can we test them in a systematic way?

In this talk, I will present a general framework for interpreting deviations in gravitational wave data,...

26. Measuring helicity of stochastic gravitational wave backgrounds

ueli pen (U)

01/11/2025, 14:50

We review GW helicity probes from LVK through LISA, PTA to CMB, and distill the kinematic projection of the three vectors consisting of two polarizations and their spatial separation, identifying the requirement of non co-linearity. LISA and PTA in their current form are thus not helicity sensitive. We present extensions that enable a measurement.

37. A binary black hole metric approximation for all practical purposes (in magnetohydrodynamics)

Luciano Combi Combi (Perimeter Institute)

01/11/2025, 15:05

Binary black holes can interact with surrounding matter, producing unique electromagnetic signatures and influencing their long-term evolution. Numerical simulations are crucial to understand the nonlinear behavior of gas and particles moving on this dynamical spacetime. We present a general binary black hole metric approximation valid at all binary separations for all practical purposes. We...

48. A Yang-Mills-like formulation of General Relativity

Erik Schnetter (Perimeter Institute for Theoretical Physics)

01/11/2025, 15:20

I present a new formulation of General Relativity. The action is quadratic in the curvature and the equations of motion involve the divergence of the Riemann tensor. I show that this formulation is well posed and is equivalent to the Einstein equations. Overall, this formulation provides a surprising and peculiar new point of view on the Einstein equations.

9. OGRePy: Object-Oriented General Relativity in Python

Prof. Barak Shoshany (Brock University)

01/11/2025, 15:35

I will present a detailed introduction to my Python package, OGRePy: An Object-Oriented General Relativity Package for Python, which will be of great interest to anyone doing research in general relativity. I will demonstrate the package's usage and features, including its ability to calculate arbitrary tensor formulas involving any combination of...

28. GW250114 reveals black hole horizon signatures

Sizheng Ma (Perimeter Institute)

01/11/2025, 15:50

The horizon of a black hole, the "surface of no return," is characterized by its rotation frequency $\Omega_H$ and surface gravity $\kappa$. A striking signature is that any infalling object appears to orbit at $\Omega_H$ due to frame dragging, while its emitted signals decay exponentially at a rate set by $\kappa$ as a consequence of gravitational redshift. Recent theoretical work predicts...

13. Rotating black holes beyond Einstein

Prof. Nicolas Yunes

01/11/2025, 16:05

I will present a new general method to find rotating black hole solutions (analytically and in closed form) for a large class of beyond Einstein theories. These solutions are valid for any black hole spin (including near-extremal black holes) and converge exponentially fast with the number of basis functions kept in the solution. These new solutions can now be used to study extreme mass-ratio...