Events Archive

Princeton Gravity Initiative - Symmetry Algebras and Black Holes in Self Dual Gravity - Noah Miller - Harvard University
Mon, Dec 11, 2023, 12:30 pm1:30 pm

This talk will explore recent insights into the structure of classical self dual gravity and non-Kerr-Newman black holes from the study of celestial holography and scattering amplitudes. “Self dual gravity” refers to a theory in which the Riemann curvature 2-form is required to be invariant under the Hodge star operator. Such spacetimes are…

Faculty, post docs, grads
Princeton Gravity Initiative - Dynamics of gaseous stars - Juhi Jang (University of Southern California)
Mon, Dec 4, 2023, 12:30 pm1:30 pm

In astrophysical fluid dynamics, stars are considered as isolated fluid masses subject to self-gravity. A classical model of a self-gravitating Newtonian star is given by the gravitational Euler- Poisson system, while a relativistic star is modeled by the Einstein-Euler system. In the talk, I will review some recent progress on the local and…

Faculty, Postdocs, graduate students
Princeton Gravity Initiative - Global stability of the Kaluza - Klein spacetime - Annalaura Stingo (École Polytechnique Paris)
Mon, Nov 27, 2023, 12:30 pm1:30 pm

The Kaluza-Klein theories represent the classical mathematical approach to the unification of general relativity with electromagnetism and more generally with gauge fields. In these theories, general relativity is considered in 1+3+d dimensions and in the simplest case d=1 dimensional gravity is compactified on a circle to obtain at low…

Faculty, Postdocs, graduate students
Princeton Gravity Initiative - On linear and non-linear stability of collisionless systems on black hole exteriors - Renato Velozo Ruiz (University of Toronto)
Mon, Nov 13, 2023, 12:30 pm1:30 pm

I will present upcoming linear and non-linear stability results concerning the asymptotic behavior of collisionless many-particle systems on black hole exteriors. On the one hand, I will discuss the decay properties of massive Vlasov fields on Schwarzschild spacetime. On the other hand, I will discuss an asymptotic stability result for the…

Faculty, Postdocs, graduate students
Princeton Gravity Initiative - Nanohertz Gravitational Waves: exploring the most massive black holes in the Universe - Luke Kelley (Northwestern University)
Mon, Nov 6, 2023, 12:30 pm1:30 pm

Earlier this year NANOGrav, along with other pulsar timing arrays, announced strong evidence for a stochastic gravitational wave (GW) background at nanohertz frequencies.  For decades, such a signal has been predicted from binaries of supermassive black holes (SMBHs).  I will present NANOGrav’s recent data and our interpretation of…

Faculty, Postdocs, graduate students
Princeton Gravity Initiative - There are still innovations in general relativistic ray tracing! - Chi-Kwan Chan (University of Arizona)
Mon, Oct 30, 2023, 12:30 pm1:30 pm

General relativistic ray tracing and radiative transfer (GRRT) are numerical techniques for simulating images of black holes.  They have played an instrumental role in both predicting and interpreting the horizon scale resolution images observed by the Event Horizon Telescope. Over the past two decades, these techniques have undergone…

Faculty, Postdocs, graduate students
Princeton Gravity Initiative - From Gaia to LISA: white dwarfs at the centre of the stellar revolution -Ilaria Caiazzo (California Institute of Technology)
Mon, Oct 23, 2023, 12:30 pm1:30 pm

This is an exciting time for stellar astrophysics as high-cadence time domain surveys (Gaia, PTF, ZTF, ATLAS, Kepler, TESS, and, in the near future, the Vera Rubin Observatory) are revolutionizing the landscape of stellar studies by allowing the exploration of the dynamic sky. Furthermore, spectroscopic surveys are ongoing (SDSS V, DESI, WEAVE,…

Faculty, Postdocs, graduate students
Princeton Gravity Initiative - Singing and Dancing with Black Holes - Vishal Baibhav (Northwestern University)
Thu, Oct 19, 2023, 2:00 pm3:00 pm

Gravitational waves have uncovered a treasure trove of nearly 90 merging black holes and neutron stars, each with its own unique story to tell. In the first part of the talk, our focus will center on black hole spins, seeking to decipher the secrets hidden within, including their origins, hometowns, and the forces driving their mergers. We will…

Faculty, Postdocs, graduate students
Princeton Gravity Initiative - Bosonic Fields in Strong-Field Gravity - Nils Siemonsen (Princeton University)
Mon, Oct 9, 2023, 12:30 pm1:30 pm

Gravitational wave and electromagnetic observations of strongly gravitating systems allow us not only to probe black holes and neutron stars, but also have the potential to uncover new fundamental physics. Superradiant bosonic clouds and boson stars are unique probes of new ultralight weakly-coupled scalar, vector, and spin-2 particles, as well…

Faculty, Postdocs, graduate students
Princeton Gravity Initiative - What’s inside a black hole - Ram Brustein (Ben-Gurion University)
Mon, Oct 2, 2023, 12:30 pm1:30 pm

I will present general arguments, based on fundamental physics principles, as to why we should expect a significant, horizon scale, departure from semiclassical gravity inside astrophysical black holes. Then, I will present a simple model which realizes this idea: the frozen star model. I will show that a static frozen star looks exactly like a…

Faculty, Postdocs, graduate students
Princeton Gravity Initiative - w(1+infinity) Symmetry in 4D Gravitational Scattering - Elizabeth Himwich
Mon, Sep 25, 2023, 12:30 pm1:30 pm

In four-dimensional asymptotically flat spacetimes, the infinite tower of soft graviton modes is known to generate a w(1+infinity) symmetry algebra at tree-level.  In this talk, I will review this symmetry and demonstrate that it acts non-trivially on massive scalar particles.  The symmetry action is derived from previously-discovered…

Faculty, Postdocs, graduate students
Princeton Gravity Initiative - Tower of states and black holes - Alex Bedroya
Mon, Sep 18, 2023, 12:30 pm1:30 pm

The towers of massive states in quantum gravity are ubiquitous and highly constrained. I will review some of the Swampland conjectures, known as distance conjectures, that quantify the universal behaviors of such towers in string theory. Due to the strong implications of distance conjectures, connecting them to more fundamental principles…

Faculty, Postdocs, graduate students
PGI Seminar Series Fall 2022|A. Sylvia Biscoveanu|MIT|"From Black Holes to the Big Bang: Astrophysics and Cosmology with Gravitational Waves and their Electromagnetic Counterparts"
Mon, Nov 28, 2022, 12:30 pm1:30 pm

The growing catalog of gravitational-wave signals from compact object mergers has allowed us to study the properties of black holes and neutron stars more precisely than ever before and has opened a new window through which to probe the earliest moments in our universe’s history. In this talk, I will demonstrate how current and future…

Faculty, post docs, grads
PGI Fall Seminar Series|Maximiliano Isi|Flatiron Instititue|"Probing Strong Gravity with Black Hole Ringdowns"
Mon, Oct 31, 2022, 12:30 pm1:30 pm

Gravitational waves provide a unique observational handle on the properties of strong, dynamical gravity. Black hole ringdowns, in particular, cleanly encode information about the structure of black holes, allowing us to test fundamental principles like the no-hair theorem and the area law. In this talk, I will review the status of this effort,…

Special Joint Gravity Group and Gravity Initiative Seminar: Neil Cornish|Montana State| "Gravitational Wave Astronomy: Where we are at, and What’s next”
Fri, May 20, 2022, 12:00 pm12:00 pm

Following the first detection of a binary black hole merger in 2015, the number of gravitational wave events has grown to almost one hundred, including binary neutron star mergers and mixed black hole, neutron star mergers. Going forward, the next few years should bring a wealth of new discoveries, including several more neutron star mergers…

PGI Spring Seminar Series|Dan Marrone|University of Arizona|"The Single Aperture Large Telescope for Universe Studies"
Mon, Apr 18, 2022, 12:30 pm12:30 pm

This year, NASA is beginning its search for a Probe-class ($1B) mission to fly in ~2032. This once-per-decade opportunity was endorsed by astro2020 as a way to achieve some of the science promised by the more complex and expensive far-infrared and X-ray missions that were prepared for the decadal survey. SALTUS, latin for leap, is a far…

PGI Spring Seminar Series|Marc Casals|CBPF|"Stability Properties and Strong Cosmic Censorship for Rotating Black Hole Spacetimes"
Mon, Apr 4, 2022, 11:30 am11:30 am

Black holes in the Universe do not exist in isolation but, rather, they are surrounded by matter. It is therefore important to study the stability properties of black holes under matter field perturbations. In this talk we will discuss the stability properties under classical field perturbations of several rotating (Kerr) black hole spacetimes…

PGI Spring Seminar|Zoe Wyatt|University of Cambridge|"Stabilizing Relativistic Fluids on Slowly Expanding Cosmological Spacetimes "
Mon, Mar 28, 2022, 12:30 pm12:30 pm

"On a background Minkowski spacetime, the relativistic Euler equations are known, for a relatively general equation of state, to admit unstable homogeneous solutions with finite-time shock formation. By contrast, such shock formation can be suppressed on background cosmological spacetimes whose spatial slices expand at an accelerated rate. The…

PGI Spring Seminar Series|Edgar Shaghoulian|University of Pennsylvania|"Applications of the Gravitational Path Integral to Black Holes and Cosmology"
Mon, Feb 28, 2022, 12:30 pm12:30 pm

I will introduce the gravitational path integral and discuss some of its modern applications. Our first application will be to the black hole information paradox, where we will see that nontrivial gravitational saddles are important in exhibiting unitarity of black hole evaporation. Our second application will be to cosmological spacetimes,…

PGI Spring Seminar|J. (Jácome) Armas|University of Amsterdam|"A Stable and Causal Model of Magnetohydrodynamics"
Mon, Feb 21, 2022, 12:30 pm12:30 pm

Magnetohydrodynamics (MHD) is a theory with a broad range of applications, from plasma physics to heavy-ion collisions and astrophysics. In this talk, I will show how methodologies in formal hydrodynamics allows to reformulate MHD in terms of symmetry considerations. In particular, I will show that MHD can be viewed as a theory of…