I’m releasing into the wild a simple code for computing neutron star structure in the slow-rotation expansion to first and second order. This code was origi...
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How to get remote jupyter to automatically open a local browser.
If you’re in the intersection of git, emacs, and persnickety about whitespace.
Our latest paper, Nonlinearities in black hole ringdowns, was just published in Physical Review Letters! This article was selected as an ❦ Editors’ Suggesti...
I am honored to have been selected as one of this year’s Sloan Research Fellows!
Hear me, Katie Bouman, and friends talk about how to snap a picture of a black hole with the Event Horizon Telescope!
I’m on Episode 42 of the Starts with a Bang Podcast
Want to hear me talk about numerical relativity and theories beyond GR?
I’m on Episode 64 of the Titanium Physicists Podcast
Just one more committee
I hosted a Quora session. It went well!
I’m on Episode 62 of the Titanium Physicists Podcast
I’m back in Pasadena!
How to do the STF multipole expansion of the magnetic potential and field (it’s been on my TODO list for a while)
So you have a function in terms of a continued fraction, and you want to compute its derivative…
The generalized harmonic formulation can be derived by adding a gauge-fixing term to the Einstein-Hilbert action
Sometimes in a numerical method, you need to be able to continuously turn a calculation on or off in space or time.
Integrability conditions when trying to solve for a conformal factor
Here to save you some algebra and column-inches
An identity between vector commutation coefficients and coframe connection coefficients
These three objects form a superalgebra! Whoa!
When can you integrate-by-parts with Lie derivatives?
Special thanks to Ben Mares for coming up with this identity.
There is a nice 4-dimensional Weyl identity that I can never seem to remember off the top of my head; so I decided I need to write this note so I don’t have ...
The Weyl decomposition, further splitting into E/B, and computing in terms of 3+1 objects
In an effort to keep myself organized, I decided I should type up some notes I have laying around.
Numerical relativity simulations provide the most precise templates for the gravitational waves produced by binary black hole mergers. However, many of t...
We present a numerical-relativity simulation of a black hole - neutron star merger in scalar-tensor (ST) gravity with binary parameters consistent with t...
This article was selected as an ❦ Editors’ Suggestion, and Featured in APS’s Physics magazine. More press coverage links here.
The Bondi-van der Burg-Metzner-Sachs (BMS) group, which uniquely describes the symmetries of asymptotic infinity and therefore of the gravitational waves...
One of the key ingredients for making binary waveform predictions in a beyond-GR theory of gravity is understanding the energy and angular momentum carri...
One of the important targets for the future space-based gravitational wave observatory LISA is extreme mass ratio inspirals (EMRIs), where long and accur...
Quasi-normal mode (QNM) modeling is an invaluable tool for characterizing remnant black holes, studying strong gravity, and testing general relativity. ...
Action-angle variables of a binary black-hole with arbitrary eccentricity, spins, and masses at 1.5 post-Newtonian order
Accurate and efficient modeling of the dynamics of binary black holes (BBHs) is crucial to their detection through gravitational waves (GWs), with LIGO/V...
We revisit a textbook example of a singularly perturbed nonlinear boundary-value problem. Unexpectedly, it shows a wealth of phenomena that seem to have ...
Perturbation theory is a crucial tool for many physical systems, when exact solutions are not available, or nonperturbative numerical solutions are intra...
Understanding the Bondi-Metzner-Sachs (BMS) frame of the gravitational waves produced by numerical relativity is crucial for ensuring that analyses on su...
We present a new study of remnant black hole properties from 13 binary black hole systems, numerically evolved using the Spectral Einstein Code. The mass...
We perform a new test of general relativity (GR) with signals from GWTC-2, the LIGO and Virgo catalog of gravitational wave detections. We search for the...
We show that an eccentric binary of black holes with misaligned spins is integrable at 2PN order. We also construct 4 out of 5 action variables at 1.5PN.
Brans-Dicke theory in Bondi-Sachs form: Asymptotically flat solutions, asymptotic symmetries and gravitational-wave memory effects
We study the structure of asymptotic null infinity in the Brans-Dicke theory of gravity
Merger dynamics create an attractive fixed-point in the space of distributions
The first astrophysically-relevant numerical simulation of merging black holes in a higher-curvature theory beyond GR.
The dividing line between bound and plunging orbits is an algebraic variety
qnm: A Python package for calculating Kerr quasinormal modes, separation constants, and spherical-spheroidal mixing coefficients
qnm is an open-source Python package for computing the Kerr quasinormal mode frequencies, angular separation constants, and spherical-spheroidal mixing coeff...
The first numerical beyond-GR binary black hole merger simulation.
A surrogate model extending the parameter space range of fully precessing quasicircular inspirals
Accurate models of gravitational waves from merging black holes are necessary for detectors to observe as many events as possible while extracting the maximu...
Real-time interactive visualizations of merging black holes in seconds!
Modeling black holes remnants directly from numerical relativity
Gravity theories beyond general relativity (GR) can change the properties of gravitational waves: their polarizations, dispersion, speed, and, importantly, e...
The grand challenges of contemporary fundamental physics—dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities an...
Black hole scalar charge from a topological horizon integral in Einstein-dilaton-Gauss-Bonnet gravity
In theories of gravity that include a scalar field, a compact object’s scalar charge is a crucial quantity since it controls dipole radiation, which can be s...
Modeling black holes’ kicks directly from numerical relativity
Finding the shape of extremal black holes in beyond-GR theories
Whenever you’ve got symmetry, you should use it!
One of the first numerical simulations of black hole mergers in beyond-GR effective field theories
Angular momentum is tricky to define in GR! Here’s an approach so that observers can all agree with each others’ measurements.
Invited review for CQG Focus Issue
Progress in understanding the structure of extremal black holes in Chern-Simons
Not all theories with long-ranged scalar fields produce dipole radiation in binaries
A generalization of symplectic integrators to non-conservative dynamics.
A major review on non-GR theories, black holes and neutron stars in non-GR theories, compact binaries in non-GR theories, and pulsar, gravitational-wave, and...
Extending Hamilton’s variational principle to nonconservative systems.
Explaining why universality emerges in compact objects.
Rapidly Rotating Black Holes in Dynamical Chern-Simons Gravity: Decoupling Limit Solutions and Breakdown
Numerical solutions for rapidly-rotating dCS black holes show where the weak-coupling expansion breaks down.
Short note simplifying a calculation in the literature.
Universal relations between the Newtonian multipole moments of rotating stars.
Connecting observables (pulsar binary pericenter precession and gravitational wave phase) to the parameters and structure of theoretical models.
Chern-Simons corrections to 1) internal structure (including mass shift) and 2) binary dynamics (including pericenter precession) of neutron stars.
The post-Newtonian calculation scheme applied to binary inspirals in a broad class of almost-GR theories.
Applying symplectic geometry to understand and refine Hamiltonian MC.
Parametrizing deviations from purely GR, vacuum black holes.
The deformation to spherically symmetric black holes under a class of corrections to general relativity.
Computing how much energy and momentum gravitational waves carry in a very broad class of almost-GR theories.
Turning an O(n^2) problem into an O(n log n) problem in radio interferometry, similar in spirit to how the fast Fourier transform operates.
Autonomous gravitational-wave searches—fully automated analyses of data that run without human intervention or assistance—are desirable for a number of re...
Coherent Network Analysis Technique for Discriminating Gravitational-wave Bursts From Instrumental Noise
How to overconstrain the problem of discriminating gravitational wave signals from detector noise and glitches.
I haven’t been posting every time I gave a talk, so here is a sporadic update. I contributed a talk to the 2021 April APS meeting. This talk is a status u...
Last week I gave an invited talk at the Spring 2020 workshop of the Black Hole Perturbation Toolkit (BHPToolkit). The BHPToolkit is a collection of open sou...
Just an update on talks I gave recently. Valeria Ferrari, Leonardo Gualtieri, and Paolo Pani hosted the conference “New Frontiers in Gravitational-Wave Astr...
My talk slides/movies from TG17 and APS17
My talk slides/movies from the EHT16 conference in Cambrige, MA
My talk slides/movies from the FF2016 conference at Northwestern
My talk slides/movies from the GR21 conference in NYC
My talks slides/movies from the 2016 April APS meeting in SLC
Interactive toy for understanding Poincaré sections and chaos
Interactive toy for visualizing relationship between polynomial roots and coefficients
Interactive tool for visualizing spherical/circular photon orbits in Kerr
Interactive tool to compute Kerr quantities
Interactive tool to compute ISCOs in Kerr