Great article about the importance of software engineering and open source code in astrophysics 🔭🧪 (and if anyone is keen to work with me on #BlackHoles lmk, I am planning to hire a software engineer soon!) 😊
www.simonsfoundation.org/2025/08/12/a...
Also a big shout-out to @sanjanacurtis.bsky.social for working closely with Lieke and myself. I am very thankful for our continued collaboration and am excited to model kilonova in 3D together soon!
It was such a pleasure seeing Lieke come in from a theoretical physics background and absolutely make this very astrophysicsy topic her own. I deeply admire her drive, tenacity, and careful approach to this complex end-to-end modelling project and am very excited for her next steps.
Finally, there is a lot to improve. For example, we need to model all ejecta components and verify that the 2D FLASH simulations capture all relevant dynamics. We also need to improve heating-rate prescriptions and modelling of composition effects.
Our results highlight the importance of self-consistent, long-term modeling of merger ejecta, and the importance of taking viewing-angle dependence into account when interpreting observed kilonova lightcurves. We find that magnetized outflows from a neutron-star remnant could explain blue kilonovae.
We investigated three remnant lifetimes and different r-process heating prescriptions to explore the impact on kilonova lightcurves and spectra.
We followed up GRMHD simulations of binary neutron-star merger remnants and their outflows via long-term 2D FLASH simulations and once homology is reached, performed SEDONA radiation transport to obtain lightcurves and spectra.
One more paper from the group out arxiv.org/abs/2508.00062 🎉 Led by Lieke Sippens Groenewegen, who finished her MSc in my group @grappainstitute.bsky.social in February, and with @sanjanacurtis.bsky.social we developed an end-to-end pipeline for kilonova lightcurves and spectra #highenergyastro 🔭🧪
Fun visit to the @einsteintelescope.bsky.social pathfinder at @maastrichtu.bsky.social yesterday with my research group. Really cool developments in the making, thanks very much for the great tour! #highenergyastro
It’s a tough life out there for massive stars 😂
and it is an absolute pleasure to still be collaborating with @gonihalevi.bsky.social who first started working with me when she was an undergraduate and I was a postdoc at UC Berkeley in 2016 :) Amazed by and proud of all the things you have done and the path you have charted out since!
There lots more work to do to evolve the simulation for longer after black-hole formation but for now it is really cool to measure the mass and spin of the newly-born black hole directly!
There's also a movie on youtube rendered by Swapnil Shankar www.youtube.com/shorts/4sisd...
Super exciting proof-of-principle work with GRaM-X lead by @gonihalevi.bsky.social following a 45 solar-mass low-metallicity progenitor star all the way to black-hole formation in full Numerical Relativity.
And one more paper just out today 🎉 The first 3D GRMHD simulation of black-hole formation in massive stellar core collapse in arxiv.org/abs/2506.20837. #highenergyastro 🔭🧪
There's many things to improve of course. For this initial study we made use of a computationally-efficient Leakage+M0 scheme, but M1 simulations are needed and in the works. Tracking explosions to late times and large distances also super important. More to come soon!
It is super rewarding to see GRaM-X produce science now and I am deeply grateful to the team for enabling this work. Large-scale software development wouldn't be possible without dedicated developers and embedding in large efforts like the einsteintoolkit.org and amrex-codes.github.io.
We then started building GRaM-X, a dynamical-spacetime GRMHD code, at @api.uva.nl @grappainstitute.bsky.social. GRaM-X dev was led by Swapnil and became the cornerstone of his PhD. You can find all the details about GRaM-X in arxiv.org/abs/2210.17509. GRaM-X will become open-source later this year.
Getting this out has been so rewarding as the science presented here builds off of 5 years of code development. I started development for zenodo.org/records/6131... togther with @eschnett.bsky.social, Roland Haas, and Steve Brandt.
This is the largest set of 3D MHD-driven supernova simulations to date and demonstrates that 3D parameter studies are now possible for extreme supernovae with modern GPU-enabled high-performance computing.
Led by former API PhD student Swapnil Shankar, we performed 12 MHD-driven core-collapse supernova simulations and systematically study the conditions under which jets can be successfully launched varying initial rotation rates and magnetic fields.
To kick off here on bluesky I wanted to share some recent work from the group. First off arxiv.org/abs/2504.11537, the first science paper produced with our new GPU-accelerated GRMHD code GRaM-X.
Thanks so much for the intro @profannawatts.bsky.social! Starting to post now 😀
astrophysicist at GRAPPA, University at Amsterdam
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