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Reposted by Philipp Mösta

Sera Markoff @profsera.bsky.social · Aug 14

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...

A Stellar Revolution: How Open-Source Tool MESA Changed the Way We Study Stars

A Stellar Revolution: How Open-Source Tool MESA Changed the Way We Study Stars on Simons Foundation

www.simonsfoundation.org

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Philipp Mösta @philippmoesta.bsky.social · Aug 5

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!

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Philipp Mösta @philippmoesta.bsky.social · Aug 5

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.

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Philipp Mösta @philippmoesta.bsky.social · Aug 5

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.

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Philipp Mösta @philippmoesta.bsky.social · Aug 5

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.

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Philipp Mösta @philippmoesta.bsky.social · Aug 5

We investigated three remnant lifetimes and different r-process heating prescriptions to explore the impact on kilonova lightcurves and spectra.

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Philipp Mösta @philippmoesta.bsky.social · Aug 5

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.

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Philipp Mösta @philippmoesta.bsky.social · Aug 5

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 🔭🧪

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Philipp Mösta @philippmoesta.bsky.social · Jul 3

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

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Philipp Mösta @philippmoesta.bsky.social · Jun 28

It’s a tough life out there for massive stars 😂

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

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!

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

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!

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

There's also a movie on youtube rendered by Swapnil Shankar www.youtube.com/shorts/4sisd...

A Black Hole is Born: 3D GRMHD Simulation of Black Hole Formation from Core-Collapse

YouTube video by Swapnil Shankar

www.youtube.com

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

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.

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

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 🔭🧪

A Black Hole is Born: 3D GRMHD Simulation of Black Hole Formation from Core-Collapse

We present the first three-dimensional, fully general-relativistic magnetohydrodynamic (3D GRMHD) simulation of a black hole (BH) formed from the collapsed core of a massive star. The ability to self-...

arxiv.org

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

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!

Philipp Mösta @philippmoesta.bsky.social · Jun 27

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.

The Einstein Toolkit

einsteintoolkit.org

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

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.

GRaM-X: A new GPU-accelerated dynamical spacetime GRMHD code for Exascale computing with the Einstein Toolkit

We present GRaM-X (General Relativistic accelerated Magnetohydrodynamics on AMReX), a new GPU-accelerated dynamical-spacetime general relativistic magnetohydrodynamics (GRMHD) code which extends the G...

arxiv.org

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

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.

CarpetX

CarpetX is a driver for the Cactus software framework. It provides adaptive mesh refinement and multi-block discretizations to applications. CarpetX uses AMReX to offer distributed memory parallelism,...

zenodo.org

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

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.

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

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.

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

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.

3D full-GR simulations of magnetorotational core-collapse supernovae on GPUs: A systematic study of rotation rates and magnetic fields

We present a series of fully three-dimensional, dynamical-spacetime general relativistic magnetohydrodynamics (GRMHD) simulations of core-collapse supernovae (CCSNe) for a progenitor of zero-age-main-...

arxiv.org

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Philipp Mösta @philippmoesta.bsky.social · Jun 27

Thanks so much for the intro @profannawatts.bsky.social! Starting to post now 😀

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Philipp Mösta @philippmoesta.bsky.social · Jun 26

astrophysicist at GRAPPA, University at Amsterdam

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Philipp Mösta @philippmoesta.bsky.social · Jun 26

yes

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