Posts by Category

Simple slow-rotation neutron star structure solver External link

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...

ssh ipython notebook tunneling magic

How to get remote jupyter to automatically open a local browser.

Elliptic Integrals in Javascript External link

I just created a repo on github for computing complete elliptic integrals in javascript. The README.md is below, and a demo after that. You might ask yoursel...

Whitespace Cleanup on Diff Lines in Emacs

If you’re in the intersection of git, emacs, and persnickety about whitespace.

Titanium Physicists podcast episode 80 External link

Hear me, Katie Bouman, and friends talk about how to snap a picture of a black hole with the Event Horizon Telescope!

On the Starts with a Bang Podcast! External link

I’m on Episode 42 of the Starts with a Bang Podcast

Talk on the Latin American Webinar on Physics External link

Want to hear me talk about numerical relativity and theories beyond GR?

On the Titanium Physicists Podcast AGAIN! External link

I’m on Episode 64 of the Titanium Physicists Podcast

Member-at-large of APS Topical Group on Gravitation

Just one more committee

Quora session on gravitational waves, LIGO, black holes External link

I hosted a Quora session. It went well!

On the Titanium Physicists Podcast! External link

I’m on Episode 62 of the Titanium Physicists Podcast

Moved to Caltech

I’m back in Pasadena!

Notes: A family of ramp functions and the Beta function

Sometimes in a numerical method, you need to be able to continuously turn a calculation on or off in space or time.

(Notes) When is a metric conformal to Ricci-flat?

Integrability conditions when trying to solve for a conformal factor

Note on simple(r) equations for Einstein-dilaton-Gauss-Bonnet and dynamical Chern-Simons theories

Here to save you some algebra and column-inches

Note on commutation coefficients in two ways

An identity between vector commutation coefficients and coframe connection coefficients

Note on exterior, interior, and Lie derivative superalgebra

These three objects form a superalgebra! Whoa!

Note on Lie derivatives and divergences

When can you integrate-by-parts with Lie derivatives?

Note on generating a divergence identity

Special thanks to Ben Mares for coming up with this identity.

Note on a (dimension-dependent) Weyl 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 ...

Notes on the Weyl, E/B, and 3+1 decompositions of Riemann, and curvature invariants

The Weyl decomposition, further splitting into E/B, and computing in terms of 3+1 objects

Notes on the pullback connection

In an effort to keep myself organized, I decided I should type up some notes I have laying around.

The location of the last stable orbit in Kerr spacetime

The dividing line between bound and plunging orbits is an algebraic variety

Numerical relativity simulation of GW150914 beyond general relativity

The first astrophysically-relevant numerical simulation of merging black holes in a higher-curvature theory beyond GR.

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...

Numerical binary black hole collisions in dynamical Chern-Simons gravity

The first numerical beyond-GR binary black hole merger simulation.

Surrogate models for precessing binary black hole simulations with unequal masses

A surrogate model extending the parameter space range of fully precessing quasicircular inspirals

The SXS Collaboration catalog of binary black hole simulations

Accurate models of gravitational waves from merging black holes are necessary for detectors to observe as many events as possible while extracting the maximu...

The binary black hole explorer: on-the-fly visualizations of precessing binary black holes

Real-time interactive visualizations of merging black holes in seconds!

High-accuracy mass, spin, and recoil predictions of generic black-hole merger remnants

Modeling black holes remnants directly from numerical relativity

Measuring stochastic gravitational-wave energy beyond general relativity

Gravity theories beyond general relativity (GR) can change the properties of gravitational waves: their polarizations, dispersion, speed, and, importantly, e...

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...

Black-hole kicks from numerical-relativity surrogate models

Modeling black holes’ kicks directly from numerical relativity

Deformation of extremal black holes from stringy interactions

Finding the shape of extremal black holes in beyond-GR theories

Separating metric perturbations in near-horizon extremal Kerr spacetimes

Whenever you’ve got symmetry, you should use it!

Numerical binary black hole mergers in dynamical Chern-Simons: I. Scalar field

One of the first numerical simulations of black hole mergers in beyond-GR effective field theories

Prescriptions for Measuring and Transporting Local Angular Momenta in General Relativity

Angular momentum is tricky to define in GR! Here’s an approach so that observers can all agree with each others’ measurements.

Black Hole Based Tests of General Relativity

Invited review for CQG Focus Issue

Extremal Black Holes in Dynamical Chern-Simons Gravity

Progress in understanding the structure of extremal black holes in Chern-Simons

Challenging the Presence of Scalar Charge and Dipolar Radiation in Binary Pulsars

Not all theories with long-ranged scalar fields produce dipole radiation in binaries

“Slimplectic” Integrators: Variational Integrators for General Nonconservative Systems

A generalization of symplectic integrators to non-conservative dynamics.

Testing General Relativity With Present and Future Astrophysical Observations

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...

The Principle of Stationary Nonconservative Action for Classical Mechanics and Field Theories

Extending Hamilton’s variational principle to nonconservative systems.

Why I-Love-Q: Explaining why universality emerges in compact objects

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.

Note on Legendre Decomposition of the Pontryagin Density in Kerr

Short note simplifying a calculation in the literature.

Three-Hair Newtonian Relations for Rotating Stars

Universal relations between the Newtonian multipole moments of rotating stars.

Parametrizing and Constraining Scalar Corrections to General Relativity

Connecting observables (pulsar binary pericenter precession and gravitational wave phase) to the parameters and structure of theoretical models.

Isolated and Binary Neutron Stars in Dynamical Chern-Simons Gravity

Chern-Simons corrections to 1) internal structure (including mass shift) and 2) binary dynamics (including pericenter precession) of neutron stars.

Probes of Strong-field Gravity (PhD Thesis) External link

MIT PhD thesis of Leo C. Stein

Post-Newtonian, Quasicircular Binary Inspirals in Quadratic Modified Gravity

The post-Newtonian calculation scheme applied to binary inspirals in a broad class of almost-GR theories.

The Geometry of Hamiltonian Monte Carlo

Applying symplectic geometry to understand and refine Hamiltonian MC.

Bumpy Black Holes in Alternative Theories of Gravity

Parametrizing deviations from purely GR, vacuum black holes.

Nonspinning Black Holes in Alternative Theories of Gravity

The deformation to spherically symmetric black holes under a class of corrections to general relativity.

Effective Gravitational Wave Stress-energy Tensor in Alternative Theories of Gravity

Computing how much energy and momentum gravitational waves carry in a very broad class of almost-GR theories.

Solving the Corner-turning Problem for Large Interferometers

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.

X-Pipeline: An Analysis Package for Autonomous Gravitational-wave Burst Searches

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.

Recent talks in Rome and Nottingham

Just an update on talks I gave recently. Valeria Ferrari, Leonardo Gualtieri, and Paolo Pani hosted the conference “New Frontiers in Gravitational-Wave Astr...