Gravitational waves from the coalescence of compact binaries provide a unique opportunity to test gravity in the strong field regime. In particular, the postmerger phase of the gravitational signal is a proxy for the nature of the remnant.

# Events Archive

## Gravity Initiative Seminar

### PGI Virtual Seminar Series | Elisa Maggio, University of Rome "Testing the nature of dark compact objects with gravitational waves"

### PGI Virtual Seminar Series | Claude Warnick, Cambridge University "Quasinormal modes of black holes"

During its ringdown phase a perturbed black-hole produces radiation at characteristic (complex) frequencies, much like the normal frequencies of a guitar string. These quasinormal frequencies carry information about the geometry of the black hole.

### PGI Virtual Seminar Series | Marcelo Disconzi, Vanderbilt University "General-relativistic viscous fluids

The discovery of the quark-gluon plasma that forms in heavy-ion collision experiments provides a unique opportunity to study the properties of matter under extreme conditions, as the quark-gluon plasma is the hottest, smallest, and densest fluid known to humanity.

### PGI Virtual Seminar Series | Lydia Bieri, University of Michigan "New Structures in Gravitational Radiation"

Gravitational waves transport information from faraway regions of the Universe. Since the first detection of gravitational waves by Advanced LIGO in September 2015, several other events have been recorded by the LIGO/VIRGO collaboration.

### PGI Virtual Seminar Series | Chris White, PU "Misaligned Accretion Flows and Their Impact on Black Hole Observations"

A priori it would be surprising if all low-luminosity supermassive black holes, such as those in the centers of M87 and our own galaxy, had accretion disks aligned with their spin.

### PGI Virtual Seminar Series | Brianna Grado-White, Brandeis "Multi-mouth Traversable Wormholes"

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### PGI Virtual Seminar Series | Eliot Quataert, PU "Horizon-scale Modeling of Black Hole Accretion"

Abstract: In this talk, I will provide an overview of theoretical models of black hole accretion aimed primarily at non-specialists. I will focus in particular on efforts to understand the dynamics of, and radiation from, plasma in the near-horizon environment, both analytically and using numerical simulations.

### PGI Virtual Seminar Series | Maya Fishbach, NU "Minding the Gap: Lessons from LIGO-Virgo’s Biggest Black Holes"

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### PGI Virtual Seminar Series | Antony Speranza, PI "Symmetries, observables, and entropy of black hole horizons"

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### PGI Virtual Seminar Series | Grigorios Fournodavlos, Sorbonne Université "Stable Big Bang formation"

In this talk we will investigate the past dynamics of cosmological solutions to Einstein's equations, containing a Big Bang singularity. More precisely, we will focus on the classical generalised Kasner examples. The celebrated "singularity'' theorem of Hawking states that the past of sufficiently small perturbations of such solutions are...

### Virtual Seminar Series | Sebastiano Bernuzzi (Friedrich-Schiller-Universität Jena) "Modeling the strong-field dynamics of binary neutron star merger"

The observation of gravitational and electromagnetic waves from a binary neutron star (BNS) merger in August 2017 conveyed unique information on the nature of matter at supranuclear densities, on the origin of short-gamma ray burst, on the production site of of heavy elements in the Universe, and on cosmography.

### PGI Virtual Seminar Series | Fani Dosopoulou, "The Merger History of Elliptical Galaxies: Mass Deficit"

Abstract: The structure and kinematics of galactic nuclei are fossil relics of the merger histories of galaxies and of the interaction between stars and SMBH binaries. Stars ejection during the SMBH binary evolution should reduce a galaxy’s central density and expand its core.

### PGI Virtual Seminar Series | Eliot Hijano Cubelos, "Where are BMS symmetries in the flat limit of AdS/CFT?"

Abstract: A holographic description of physics in Minkowski space is still elusive. A tempting approach is to implement a flat limit from AdS/CFT. Such a limit has not properly been understood, even at the level of the symmetries of the theory; How do BMS symmetries emerge from the flat limit of the asymptotic symmetries of anti-de Sitter space...

### PGI Virtual Seminar Series | Carolyn Raithel, "Constraining the Neutron Star Equation of State with Gravitational Wave Events"

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### PGI Virtual Seminar Series | Jonathan Wing-hong Luk, “Some singular spacetimes in general relativity”

Abstract: I will describe a few classes of solutions to the Einstein equations whose metrics are singular or highly oscillatory, and discuss the relation between them. The singular solutions include as special examples impulsive gravitational waves and null dust shell solutions.

### PGI Virtual Seminar Series | Yakov Shlapentokh-Rothman, "Naked Singularities for the Einstein Vacuum Equations: The Exterior Solution"

Abstract: We will start by recalling the weak cosmic censorship conjecture. Then we will review Christodoulou's construction of naked singularities for the spherically symmetric Einstein-scalar field system.

### PGI Virtual Seminar Series | Lia Medeiros, IAS "Gravitational Test beyond the First Post-Newtonian Order with the EHT"

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### Princeton Gravity Initiative | PCTS Workshop, “Exploring Supermassive Black Holes”

**October 14, 11:00 am-2:30 pm EDT (GMT-4) time | Day 1: SMBH-galaxy co-evolution (observations)**

**Marta Volonteri**11:00-11:30am

**Xin Liu**11:30-12:00pm

Break 15 min

### PGI Virtual Seminar Series | Matthew Heydeman, "Statistical Mechanics of Near-BPS Black Holes from N=4 JT Supergravity"

### PGI Virtual Seminar Series | Gabriele Benomio, "A new instability for higher dimensional black holes"

Abstract: In contrast with the classical stability of stationary, asymptotically flat black holes in four dimensions, some families of higher dimensional black holes suffer from dynamical instabilities.