(Tracking Spin before, between and after gravitational collapse) QuasiLocal Toolkit: Mathematical Software for Spacetime Rotation and Angular Momentum Conservation
Abstract
"The QuasiLocal Toolkit isn't just J = (1/3)αr²f. It's the complete mathematical infrastructure that MAKES that formula valid, efficient, and usable in real numerical relativity, with surgical excision, coordinate freedom, constraint preservation, and machine-precision validation against exact solutions." Without the full toolkit, you get: A formula that breaks during surgery No way to validate your implementation No handling of general surfaces/coordinates No detection of wrong/mislabeled fields With the full toolkit, you get: Mathematical guarantees Surgical flux conservation Coordinate freedom Validation against Kerr/Schwarzschild Production-ready for NR simulations Core Capabilities: Axisymmetric Angular Momentum Clebsch-Komar Identity: General angular momentum decomposition Surgical Flux Theorem: ΔJ computation across excision boundaries Vorticity Bounds: verification Zero Angular Momentum Detection: α≡0 or dβ≡0 ⇒ J=0 Helicity Conservation: d/dλ ∫ V∧dV = 0 tracking For Numerical Relativity: Reads SpEC, Cactus HDF5/ASCII formats Coordinate transformations between common systems Killing vector generation for known spacetimes Surface and volume integration on arbitrary grids Validation against analytic solutions Why This Matters: Traditional methods need horizon finding (expensive, fails during mergers). This approach uses Clebsch fields (always defined, even inside horizons). This enables: Rotation tracking during black hole formation Angular momentum measurement without horizons Surgical excision with conservation guarantees Local rotation density maps (not just global quantities) Validation Status: Kerr metric: J = Ma to machine precision (10^-14 relative error) Schwarzschild: J = 0, M correct Flat space: J = 0, M = 0 Surgical flux: Conservation to numerical tolerance For Researchers: This toolkit enables new studies of: Differential rotation in black holes Angular momentum transport in mergers Vorticity structure of gravitational collapse Surgical effects on rotation Rotation without horizon assumptions The formula is the destination with the toolkit is the process turning theorems about spacetime rotation into tools for understanding the universe's spin. Collaboration Welcome: We actively welcome collaborations on: Extending to non-axisymmetric cases Integrating with other NR codes Developing new visualization tools Applying to specific astrophysical scenarios Educational materials and tutorials contact: raydperu@gmail.com, Research Lead. Keywords: general relativity, numerical relativity, angular momentum, quasilocal quantities, Clebsch representation, vorticity, black holes, gravitational waves, mathematical software, scientific computing
Fields of Study & Subjects
Pulsars and Gravitational Waves Research
Relativity and Gravitational Theory
Black Holes and Theoretical Physics
Publication details
- Journal / source
- Zenodo (CERN European Organization for Nuclear Research)
- Publication date
- 15 January 2026