Hello, world! As a first post, I thought I'd introduce myself; I'm a NASA Einstein Fellow @ Cornell studying gravitational waves as a part of @sxs-collaboration.bsky.social, @ligo.org, and @lisacommunity.bsky.social. I study many aspects of gravity, but my latest ambition has been testing GR!

Check out the latest SXS preprint, led by member Yuan Feng of @caltech.edu! arxiv.org/abs/2605.03947 Effects of magnetically driven shocks on nucleosynthesis and kilonovae from neutron star mergers What's it about? 1/ ⚛️🧪🔭

Can potential subsolar-mass gravitational wave events reveal their origin? New preprint by SXS researchers @caltech.edu and Cornell: Eccentricity as a signature of hierarchical subsolar-mass mergers in collapsar disks Jiaxi Wu, Elias Most, et al. arxiv.org/abs/2604.26912 What's it about? 1/2 ⚛️🧪🔭

Eccentricity as a signature of hierarchical subsolar-mass mergers in collapsar disks

In this work, we investigate gravitational-wave signatures of a proposed subsolar-mass merger scenario resulting from fragmentation inside a collapsar accretion disk. This scenario has gained recent i...

arxiv.org

If you follow the @sxs-collaboration.bsky.social account, you've probably seen some of Keefe's research before!

Leo C. Stein@duetosymmetry.com · 3mo ago

Everyone say hi to @keefemitman.bsky.social! Keefe is an expert in black holes, gravitational waves, data analysis, and especially fun things like gravitational memory.

Everyone say hi to @keefemitman.bsky.social! Keefe is an expert in black holes, gravitational waves, data analysis, and especially fun things like gravitational memory.

📄New Preprint by Khairnar et al. arxiv.org/abs/2603.24661. ⚛️🧪 Here we improve the robustness of center-of-mass (CoM) frame fixing method for NR waveforms. We reduce the sensitivity of the fitting parameters by modeling the out-spiraling oscillations of the CoM charge using post-Newtonian results.

Fixing the center-of-mass frame of numerical relativity waveforms using the post-Newtonian center-of-mass charge

The Bondi--van der Burg--Metzner--Sachs (BMS) frame of gravitational waves produced by numerical relativity (NR) simulations is crucial for building accurate waveform models. A proper comparison of NR...

arxiv.org

Congrats to SXS member Elias Most (Asst. Prof. at @caltech.edu) on being named one of the 126 Sloan Research Fellows for 2026! www.caltech.edu/about/news/t...

Three Professors Named 2026 Sloan Fellows

Elias Most, Huy Tuan Pham, and Lingfu Zhang have been selected to receive the 2026 Sloan Research Fellowship.

caltech.edu

Alfred P. Sloan Foundation@sloanfoundation.bsky.social · 6mo ago

Congrats to the 126 early-career scholars awarded a 2026 Sloan Research Fellowship, whose creativity and innovation set them apart as the next generation of scientific leaders! Our #SloanFellows represent 7 fields and 44 institutions across the US and Canada. Full list: sloan.org/fellowships/...

Two of our papers on black-hole scattering have been published in Physical Review D! 🎉 To celebrate, here is a visualisation of the gravitational wave emission from a close scattering encounter: youtu.be/u9wBZEYfyAM Paper 1: doi.org/10.1103/p6fx... Paper 2: doi.org/10.1103/bdsb...

Our latest paper explores what happens when we push numerical relativity to the extreme when simulating black-hole scattering with the Spectral Einstein Code (SpEC). Check out this thread by the lead author to find out more!

Olly Long@hyperbolly.bsky.social · 9mo ago

How much information can we gain by pushing numerical relativity to its limit by simulating black hole scattering encounters? My latest paper (below) explores these extreme regions of the black-hole scattering parameter space using simulations generated using the Spectral Einstein Code (SpEC).

🎉 Happy paper publication day! 🎉 Our third catalog of binary black hole simulations, now published in Classical and Quantum Gravity. And it's open access! Scheel et al. 2025 Class. Quantum Grav. 42 195017 iopscience.iop.org/article/10.1... Also on the @arxiv.bsky.social at arxiv.org/abs/2505.13378

The SXS Collaboration's third catalog of binary black hole simulations

We present a major update to the Simulating eXtreme Spacetimes (SXS) Collaboration's catalog of binary black hole simulations. Using highly efficient spectral methods implemented in the Spectral Einst...

arxiv.org

SXS Collaboration@sxs-collaboration.bsky.social · last yr.

We are excited to release a major update to our catalog of binary black hole simulations, available at arxiv.org/abs/2505.13378! Such simulations are key to LIGO/Virgo/KAGRA being able to extract science from their gravitational wave detections. 1/13 🧪⚛️🔭

Just published in Physical Review Letters! Check out this article by SXS researchers Boyeneni, Wu and Most (@caltech.edu) on interpreting colliding black holes similar to the attraction of two electric charges. 🔒 journals.aps.org/prl/abstract... 🔓 arxiv.org/abs/2504.15978 🧪⚛️🔭

Cranking up the temperature! SXS researchers Hai-Yang Wang, Elias Most and Philip Hopkins (@caltech.edu) show how hot flows around supermassive black hole binaries with strong magnetic fields alter their feeding behavior. Full results at arxiv.org/abs/2508.16855

Earthquakes on neutron stars?! SXS researchers Louis Burnaz and Elias Most (@caltech.edu) and Ashley Bransgrove (Princeton) simulate how these could be detected in signals from very active radio burst transients. Read their results at arxiv.org/abs/2508.18033

A spacetime waltz. Simulations from @sxs-collaboration.bsky.social consistent with our 86 most confident new detections, each showing the orbiting components and their emitted gravitational waves www.youtube.com/watch?v=3B6W... 🎬I Markin/T Dietrich/H Pfeiffer #GWTC4 🔭🧪⚛️☄️🐚

Visualization of the GWTC-4.0 events

YouTube video by Max Planck Institute for Gravitational Physics

youtube.com

🎉 Great news 🎉 — yesterday CQG accepted our third catalog paper!! The accepted manuscript can be found on their site here: iopscience.iop.org/article/10.1... 🧪⚛️🔭

SXS Collaboration@sxs-collaboration.bsky.social · last yr.

We are excited to release a major update to our catalog of binary black hole simulations, available at arxiv.org/abs/2505.13378! Such simulations are key to LIGO/Virgo/KAGRA being able to extract science from their gravitational wave detections. 1/13 🧪⚛️🔭

2025 ICTP Dirac Medal Goes to Gravity Explorers: The award is attributed to four scientists who have turned black holes into windows onto the deepest laws of nature www.ictp.it/news/2025/8/...

We now have our first paper on binary black hole scattering simulations generated with the Spectral Einstein Code (SpEC)! For more info on modelling these high-energy systems, see this thread by the lead author!

Olly Long@hyperbolly.bsky.social · last yr.

What happens when high-velocity black holes hurtle past each other in a close encounter, deflecting through spacetime but never merging? My latest paper (below) presents the first simulations of black hole scattering generated using the Spectral Einstein Code (SpEC). (1/6)

Check out this article about star quakes and monster shocks — research done by SXS collaboration members Yoonsoo Kim and Elias Most, both at @caltech.edu

Caltech@caltech.edu · last yr.

To better understand the extreme physics underlying such a grizzly demise, researchers at Caltech are using supercomputers to simulate black hole–neutron star collisions. www.caltech.edu/about/news/s...

I’m incredibly proud to be part of this and to have my simulations turn into the first publicly available scattering and dynamical capture waveforms! Below is a plot I made for the Einstein Toolkit Blue Book (arXiv:2503.12263) showing the waveforms SXS:BBH:3999 (scatter) and SXS:BBH:4000 (capture).

SXS Collaboration@sxs-collaboration.bsky.social · last yr.

We are excited to release a major update to our catalog of binary black hole simulations, available at arxiv.org/abs/2505.13378! Such simulations are key to LIGO/Virgo/KAGRA being able to extract science from their gravitational wave detections. 1/13 🧪⚛️🔭

Bonus: here's an animation I generated showing how the sausage was made. Each frame is one commit from the paper repo.

We are excited to release a major update to our catalog of binary black hole simulations, available at arxiv.org/abs/2505.13378! Such simulations are key to LIGO/Virgo/KAGRA being able to extract science from their gravitational wave detections. 1/13 🧪⚛️🔭

When simulating orbiting black holes, we move our grid with the holes! One of the key lessons of general relativity is coordinates are meaningless. We exploit this to choose comoving coordinates where the metric changes as little as possible. www.youtube.com/watch?v=j4WG... 🧪⚛️🔭

A visualization of the moving mesh in binary black hole merger inspiral simulation

YouTube video by SXS Collaboration

youtube.com

A recent paper led by collaboration members Yoonsoo Kim and Elias Most (both at Caltech) is in @aasnova.org today! This work explores the formation of strongly magnetized "monster" shocks and a transient "black hole pulsar" state from mergers of a magnetized neutron star and a black hole. ⚛️🧪🔭

AAS Nova@aasnova.org · last yr.

Monster shocks and a “pulsar-like” black hole phase might form when a black hole collides with a neutron star. Could this cosmic clash produce observable electromagnetic signals? aasnova.org/2025/05/12/b... @caltech.edu 🔭🧪

When two black holes merge, they form a bigger black hole. The mass of the bigger black hole will be around 95% of the mass of its two parent black holes. The remaining 5% is carried away as the energy in the gravitational waves #BlackHoleWeek 2/🧵 🎞️: @sxs-collaboration.bsky.social

a black hole in the middle of a galaxy

Alt: Simulation of two black holes merging. They appear black against the background of stars, but the light from the stars is distorted by their gravity

media.tenor.com

Happy #BlackHoleWeek! To celebrate, we’re releasing the highest-resolution ray-traced still from one of our simulations to date. This skeet has a low res preview. To zoom into the full 43,200 × 21,600 pixel rendering, head to www.black-holes.org/2025/05/07/B... 🧪⚛️🔭

A recent paper presents a PN-inspired framework to measure eccentricity directly from gravitational waves 🌊🌀 Focused on non-precessing eccentric BBH mergers, using mode modulations driven by the eccentricity. 📄 arxiv.org/abs/2502.02739

Also, how do we feel about this account's handle? Should we switch to using our domain, becoming @black-holes.org?

Our web site, www.black-holes.org, has silently re-launched! Now that we're using Jekyll and github pages, we hope to give more frequent updates about our latest research. What do you want to see there? Leave a comment below! 🧪⚛️🔭

Wake up babe, new preprint just dropped Length dependence of waveform mismatch: a caveat on waveform accuracy Mitman, Stein, et al. arxiv.org/abs/2502.14025 ⚛️🧪🔭