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

Erik Schnetter; Philipp M\"osta; Roland Haas; Swapnil Shankar

arxiv: 2504.11537 · v1 · submitted 2025-04-15 · 🌌 astro-ph.HE · gr-qc

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

Swapnil Shankar , Philipp M\"osta , Roland Haas , Erik Schnetter This is my paper

Pith reviewed 2026-05-22 19:56 UTC · model grok-4.3

classification 🌌 astro-ph.HE gr-qc

keywords core-collapse supernovaemagnetorotational mechanismgeneral relativistic MHDjet formationstellar rotationmagnetic fieldstype Ic supernovae3D simulations

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The pith

Simulations show only the fastest-rotating, most strongly magnetized cores produce high-velocity ejecta suitable for broad-lined type Ic supernovae.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper runs a grid of twelve three-dimensional general-relativistic magnetohydrodynamics simulations of the collapse of a 25 solar-mass star. It varies the initial magnetic-field strength between 10^11 and 10^12 Gauss and the core rotation rate between 0.14 and 2.5 rad/s while always resolving the shock region at 1.48 km or better. Models with the stronger field and rotation rates of 2 rad/s or higher launch jets that reach ejecta speeds above 15,000 km/s. These speeds match the requirements for broad-lined type Ic supernovae. Intermediate rotation rates produce jets that bend sideways and yield more spherical ejecta that could be mistaken for neutrino-driven explosions.

Core claim

In fully three-dimensional dynamical-spacetime GRMHD simulations of a 25 solar-mass progenitor, models with initial magnetic field B0 = 10^12 G and rotation rates Omega0 >= 2.0 rad/s produce ejecta velocities gtrsim 15000 km/s and are therefore suitable candidates for broad-lined type Ic supernova progenitors, whereas models with B0 = 10^11 G fail to explode and models with B0 = 10^12 G and Omega0 = 1.0-1.5 rad/s form bending jets that give the ejecta a more spherical character.

What carries the argument

Magnetorotational jet formation driven by the combination of initial magnetic field strength B0 and rotation rate Omega0 in full general-relativistic MHD.

If this is right

Models with B0=10^12 G and Omega0=(1.0,1.5) rad/s form jets that bend sideways and produce more spherical ejecta.
Models with B0=10^11 G fail to explode within 190-260 ms.
Models with B0=10^12 G and Omega0 >=2.0 rad/s reach ejecta velocities gtrsim15000 km/s and match broad-lined type Ic requirements.
All models resolve the entire shock-containing region at least at 1.48 km and evolve for 190-260 ms after collapse.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Broad-lined Ic events should preferentially come from progenitors whose cores rotate at or above roughly 2 rad/s if the velocity threshold holds.
The bending-jet cases suggest that some apparently neutrino-driven explosions could actually be magnetorotationally powered.
Extending these runs to later times would test whether the high-velocity material continues to accelerate or eventually slows.

Load-bearing premise

The chosen initial rotation profiles and magnetic-field configurations accurately represent the conditions inside a real collapsing stellar core at the onset of collapse.

What would settle it

An observed broad-lined type Ic supernova whose progenitor rotation rate is measured below 2 rad/s yet still shows ejecta velocities above 15000 km/s would contradict the reported threshold.

read the original abstract

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-sequence (ZAMS) mass $25\, M_\odot$. We simulate a total of 12 models for simulation times in the range $190-260\, \mathrm{ms}$ to systematically study the effect of rotation rates and magnetic fields on jet formation via the magnetorotational mechanism. We have performed simulations on OLCF's Frontier using the new GPU-accelerated dynamical-spacetime GRMHD code \theCode for magnetic fields $B_0 = (10^{11}, 10^{12})\, \mathrm{G}$ and rotation rates $\Omega_0 = (0.14, 0.5, 1.0, 1.5, 2.0, 2.5)\, \mathrm{rad/s}$. We always resolve the entire region containing the shock with a resolution of at least $1.48\, \mathrm{km}$. We find that models with $B_0=10^{11}\, \mathrm{G}$ fail to explode, while those with $B_0=10^{12}\, \mathrm{G}$ show a wide range of jet morphologies and explosive outcomes depending on the rotation rate. Models with $B_0=10^{12}\, \mathrm{G}$ and $\Omega_0=(1.0,1.5)\, \mathrm{rad/s}$ form jets that bend sideways, giving the ejecta a more spherical character, and possibly representing explosions that \textit{appear} neutrino-driven even though they are magnetorotationally-driven. Models with $B_0=10^{12}\, \mathrm{G}$ and $\Omega_0\geq2.0\, \mathrm{rad/s}$ show ejecta velocities $\gtrsim15000\, \mathrm{km/s}$, making them suitable candidates for broad-lined type Ic supernova progenitors. This work represents the largest set of 3D general-relativistic GRMHD simulations studying magnetorotational supernovae in full GR and demonstrates the potential of systematic studies with GPU-accelerated 3D simulations of CCSNe.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This is the largest published grid of 3D full-GR GRMHD core-collapse runs, and it maps how rotation rate and field strength control jet shape and ejecta speed, with bent jets at intermediate spin as the most interesting outcome.

read the letter

The punchline is that this is the largest published grid of 3D full-GR GRMHD core-collapse runs, and it maps how rotation rate and field strength control jet shape and ejecta speed, with bent jets at intermediate spin as the most interesting outcome. They ran 12 models for a 25 solar mass progenitor, stepping initial rotation from 0.14 to 2.5 rad/s at two field strengths, all evolved in dynamical spacetime with the shock region resolved to at least 1.48 km and followed for 190-260 ms. The GPU code made the grid feasible. Weak fields produce no explosion, strong fields with moderate rotation bend the jets sideways so the ejecta look more spherical, and the fastest rotators reach ejecta speeds above 15,000 km/s that line up with broad-lined Ic events. The bent-jet cases are a useful addition because they offer one way a magnetorotational explosion could be misread as neutrino-driven in observations. The numerical effort is straightforward and the trends with the two parameters come through clearly. The main limitation is the initial conditions. The runs use uniform or dipolar fields and constant rotation profiles. Real pre-collapse cores carry differential rotation and fields that stellar evolution has tangled, and jet terminal velocity is known to depend on those details. The high speeds and specific morphologies reported here could therefore be tied to the chosen idealization rather than generic. The abstract gives no convergence tests or viscosity settings, so those would need checking. This work is aimed at people running or comparing supernova simulations and at observers who want to link energetic events to progenitor properties. Anyone who needs concrete numbers from full-GR GRMHD for a 25 solar mass star will find the scan useful. I would send it for peer review. The computational scale and the parameter trends are worth referee attention even with the standard questions about initial-condition realism.

Referee Report

1 major / 2 minor

Summary. The manuscript reports a systematic set of 12 three-dimensional dynamical-spacetime GRMHD simulations of core-collapse supernovae for a 25 solar-mass progenitor. It varies initial magnetic field strengths (10^11 G and 10^12 G) and rotation rates (0.14 to 2.5 rad/s), evolving each model for 190-260 ms at a minimum resolution of 1.48 km throughout the shock region. The central finding is that B0 = 10^12 G models with Omega0 >= 2.0 rad/s produce ejecta velocities greater than or equal to 15000 km/s and are therefore proposed as candidates for broad-lined type Ic supernova progenitors, while lower fields fail to explode and intermediate rotations yield bent jets with more spherical ejecta.

Significance. If the results hold, the work supplies a useful parameter survey of magnetorotational jet formation in full general relativity. The scale of the study (twelve 3D runs) and the use of GPU-accelerated dynamical-spacetime GRMHD code represent a technical advance that enables systematic exploration of rotation and magnetic-field effects on explosion morphology and ejecta kinematics.

major comments (1)

The claim that B0=10^12 G and Omega0 >=2.0 rad/s models are suitable broad-lined Ic candidates rests on the reported ejecta velocities being representative of real progenitors. The initial data employ constant-Omega rotation profiles and uniform or dipolar magnetic fields (described in the initial-conditions section). Real pre-collapse cores are expected to possess differential rotation and tangled fields set by stellar evolution; because jet formation and terminal velocity are known to depend sensitively on angular-momentum distribution and field geometry, the high-velocity outcome may be specific to the chosen idealization. A sensitivity test or expanded discussion of this limitation is required to support the applicability statement.

minor comments (2)

The abstract refers to 'theCode'; replace with the actual code name or a citation.
Clarify the sentence stating that bent-jet models 'appear neutrino-driven even though they are magnetorotationally-driven' to prevent misreading by non-specialist readers.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their constructive and detailed review of our manuscript. We have addressed the major comment by expanding the discussion of limitations in the initial conditions while noting the computational constraints on additional tests.

read point-by-point responses

Referee: The claim that B0=10^12 G and Omega0 >=2.0 rad/s models are suitable broad-lined Ic candidates rests on the reported ejecta velocities being representative of real progenitors. The initial data employ constant-Omega rotation profiles and uniform or dipolar magnetic fields (described in the initial-conditions section). Real pre-collapse cores are expected to possess differential rotation and tangled fields set by stellar evolution; because jet formation and terminal velocity are known to depend sensitively on angular-momentum distribution and field geometry, the high-velocity outcome may be specific to the chosen idealization. A sensitivity test or expanded discussion of this limitation is required to support the applicability statement.

Authors: We agree that the constant-Omega rotation profiles and uniform or dipolar magnetic field configurations represent an idealization relative to the differential rotation and tangled fields expected from stellar evolution. These choices were adopted to systematically isolate the effects of rotation rate and field strength in a controlled parameter study, following standard practice in the magnetorotational supernova literature. We acknowledge that jet morphology and terminal velocities can depend sensitively on the angular-momentum distribution and field geometry. Performing dedicated sensitivity tests with differential rotation and more complex fields would require a new suite of computationally expensive 3D dynamical-spacetime GRMHD simulations that is beyond the scope of the present work. In the revised manuscript we have added an expanded discussion (new subsection in the conclusions) that explicitly states this limitation, discusses its implications for the applicability of the high-velocity models to broad-lined Ic progenitors, and cites relevant studies on differential rotation effects to provide appropriate context and caveats. revision: partial

Circularity Check

0 steps flagged

No circularity: direct numerical outcomes from GRMHD evolution

full rationale

The paper evolves the GRMHD equations forward in time from fixed initial conditions (B0, Omega0 profiles) and reports the resulting ejecta velocities and morphologies as simulation outputs. No derived quantity is defined in terms of a fitted parameter that is then relabeled a prediction, no self-citation chain supports a load-bearing uniqueness claim, and no ansatz is smuggled via prior work. The central results are therefore independent of the reported values themselves.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

The study rests on standard GRMHD equations and a fixed 25 M_sun progenitor model; the two magnetic-field strengths and six rotation rates are the only quantities varied systematically.

free parameters (2)

Initial magnetic field strength B0
Set to 10^11 G or 10^12 G as the two values explored.
Initial rotation rate Omega0
Set to the six discrete values 0.14, 0.5, 1.0, 1.5, 2.0, 2.5 rad/s.

axioms (2)

standard math The GRMHD equations in dynamical spacetime accurately describe the collapse and jet-launching phase.
Invoked by the choice of full-GR code.
domain assumption The 25 M_sun ZAMS progenitor model provides realistic initial density, rotation, and magnetic-field profiles.
Used as the starting condition for all runs.

pith-pipeline@v0.9.0 · 5973 in / 1453 out tokens · 56892 ms · 2026-05-22T19:56:39.171044+00:00 · methodology

discussion (0)

Forward citations

Cited by 1 Pith paper

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