Holographic computations with SageMath

Éric Gourgoulhon1 based on a collaboration with Dmitry Ageev2, Irina Ya. Aref’eva2 and Anastasia A. Golubtsova3

1 Laboratoire Univers et Théories, Observatoire de Paris, CNRS, Université PSL, Université de Paris, Meudon, France

2 Steklov Mathematical Institute, Moscow, Russia

3 Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna, Russia

Holographic QCD at high densities, neutron stars and gravitational waves APC, Paris 27 November 2019

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 1 / 25 Outline

1 Differential geometry with SageMath

2 Example 1: black branes in 5D Lifshitz-like spacetimes

3 Example 2: near-horizon geometry of the extremal Kerr black hole

4 Conclusions

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 2 / 25 Differential geometry with SageMath Outline

1 Differential geometry with SageMath

2 Example 1: black branes in 5D Lifshitz-like spacetimes

3 Example 2: near-horizon geometry of the extremal Kerr black hole

4 Conclusions

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 3 / 25 Differential geometry with SageMath The context: computational tools developed at LUTH

LORENE: library for solving PDE equations with spectral methods in spherical coordinates https://lorene.obspm.fr/ [C++] CoCoNut: GR-hydro code for 3D gravitational collapse [with U. Valencia] https://www.uv.es/coconut/ [C++] Kadath: library for solving PDE equations with spectral methods (generic coordinates) https://kadath.obspm.fr/ [C++] Gyoto: code for geodesic computation (ray-tracing) [with LESIA] https://gyoto.obspm.fr/ [C++, Python] CompOSE: Data base of nuclear matter equations of state https://compose.obspm.fr/ SageManifolds: differential geometry and tensor calculus with SageMath https://sagemanifolds.obspm.fr/ [Python]

All these tools are free software (GPL)

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 4 / 25 SageMath is free (GPL v2) Freedom means 1 everybody can use it, by downloading the software from http://sagemath.org 2 everybody can examine the source code and improve it

SageMath is based on Python no need to learn any specific syntax to use it Python is a powerful object oriented language, with a neat syntax SageMath benefits from the Python ecosystem (e.g. Jupyter notebook)

SageMath is developed by an enthusiastic community mostly composed of mathematicians welcoming newcomers

Differential geometry with SageMath SageMath in a few words

SageMath( nickname: Sage) is a free open-source computer algebra system

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 5 / 25 SageMath is based on Python no need to learn any specific syntax to use it Python is a powerful object oriented language, with a neat syntax SageMath benefits from the Python ecosystem (e.g. Jupyter notebook)

SageMath is developed by an enthusiastic community mostly composed of mathematicians welcoming newcomers

Differential geometry with SageMath SageMath in a few words

SageMath( nickname: Sage) is a free open-source computer algebra system

SageMath is free (GPL v2) Freedom means 1 everybody can use it, by downloading the software from http://sagemath.org 2 everybody can examine the source code and improve it

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 5 / 25 SageMath is developed by an enthusiastic community mostly composed of mathematicians welcoming newcomers

Differential geometry with SageMath SageMath in a few words

SageMath( nickname: Sage) is a free open-source computer algebra system

SageMath is free (GPL v2) Freedom means 1 everybody can use it, by downloading the software from http://sagemath.org 2 everybody can examine the source code and improve it

SageMath is based on Python no need to learn any specific syntax to use it Python is a powerful object oriented language, with a neat syntax SageMath benefits from the Python ecosystem (e.g. Jupyter notebook)

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 5 / 25 Differential geometry with SageMath SageMath in a few words

SageMath( nickname: Sage) is a free open-source computer algebra system

SageMath is free (GPL v2) Freedom means 1 everybody can use it, by downloading the software from http://sagemath.org 2 everybody can examine the source code and improve it

SageMath is based on Python no need to learn any specific syntax to use it Python is a powerful object oriented language, with a neat syntax SageMath benefits from the Python ecosystem (e.g. Jupyter notebook)

SageMath is developed by an enthusiastic community mostly composed of mathematicians welcoming newcomers

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 5 / 25 Differential geometry with SageMath Tensor calculus with SageMath

SageManifolds project: extends SageMath towards differential geometry and tensor calculus

https://sagemanifolds.obspm.fr fully included in SageMath (after review process) ∼ 15 contributors (developers and reviewers) cf. https://sagemanifolds.obspm.fr/ authors.html dedicated mailing list help: https://ask.sagemath.org

2 Stereographic-coordinate frame on S

Everybody is very welcome to contribute =⇒ visit https://sagemanifolds.obspm.fr/contrib.html

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 6 / 25 Differential geometry with SageMath Current status

Already present (SageMath 8.9): differentiable manifolds: tangent spaces, vector frames, tensor fields, curves, pullback and pushforward operators, submanifolds standard tensor calculus (tensor product, contraction, symmetrization, etc.), even on non-parallelizable manifolds, and with all monoterm tensor symmetries taken into account Lie derivatives of tensor fields differential forms: exterior and interior products, exterior derivative, Hodge duality multivector fields: exterior and interior products, Schouten-Nijenhuis bracket affine connections (curvature, torsion) pseudo-Riemannian metrics computation of geodesics (numerical integration)

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 7 / 25 Differential geometry with SageMath Current status

Already present (cont’d): some plotting capabilities (charts, points, curves, vector fields) parallelization (on tensor components) of CPU demanding computations extrinsic geometry of pseudo-Riemannian submanifolds series expansions of tensor fields 2 symbolic backends: Pynac/Maxima (SageMath’s default) and SymPy

Future prospects: more symbolic backends (Giac, FriCAS, ...) more graphical outputs symplectic forms, fibre bundles, spinors, integrals on submanifolds, variational calculus, etc. connection with numerical relativity: use SageMath to explore numerically-generated spacetimes

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 8 / 25 Example 1: black branes in 5D Lifshitz-like spacetimes Outline

1 Differential geometry with SageMath

2 Example 1: black branes in 5D Lifshitz-like spacetimes

3 Example 2: near-horizon geometry of the extremal Kerr black hole

4 Conclusions

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 9 / 25 Example 1: black branes in 5D Lifshitz-like spacetimes Quark-gluon plasma in the gauge/gravity duality

Quark-gluon plasma (QGP) in heavy-ion collisions: low-viscosity fluid with anisotropic pressure (px < py)

Thermalization of QGP ≡ 5D black hole formation

Gauge theory: QCD Gravity: 5D Lifshitz-like spacetime (anisotropic generalization of AdS5) supported by magnetic field with formation of a black brane (Vaidya-type collapse) Results: faster thermalization in the transversal Spacetime diagram of a direction; evolution of the entanglement entropy heavy-ion collision (LHC) −25 τ0 ' 0.2 fm/c = 6 10 s

τ1 ∼ 10τ0

[Aref’eva, Golubtsova & Gourgoulhon, J. High Ener. Phys. 09(2016), 142] [Ageev, Aref’eva, Golubtsova & Gourgoulhon, Nucl. Phys. B 931, 506 (2018)]

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 10 / 25 Example 1: black branes in 5D Lifshitz-like spacetimes Black branes in 5D Lifshitz-like spacetimes

The SageMath notebook: https://nbviewer.jupyter.org/github/sagemanifolds/SageManifolds/ blob/master/Notebooks/SM_Lifshitz_black_brane.ipynb

In the nbviewer menu, click on the icon to run an interactive version on a Binder server.

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 11 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole Outline

1 Differential geometry with SageMath

2 Example 1: black branes in 5D Lifshitz-like spacetimes

3 Example 2: near-horizon geometry of the extremal Kerr black hole

4 Conclusions

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 12 / 25 Let us explore this geometry with a SageMath notebook: https://nbviewer.jupyter.org/github/sagemanifolds/SageManifolds/ blob/master/Notebooks/SM_extremal_Kerr_near_horizon.ipynb In the nbviewer menu, click on the icon to run an interactive version on a Binder server.

Example 2: near-horizon geometry of the extremal Kerr black hole Near-horizon geometry of the extremal Kerr black hole

Extremal Kerr black hole: a = m ⇐⇒ κ = 0 (degenerate horizon) 2 Near-horizon geometry of extremal 4D Kerr is similar to AdS2 × S geometry; it has has extended isometry group: SL(2, R) × U(1), instead of merely R × U(1) for Kerr metric [Bardeen & Horowitz, PRD 60, 104030 (1999)] Near-horizon geometry of extremal Kerr black hole is at the basis of the Kerr/CFT correspondence (see [Compère, LRR 20, 1 (2017)] for a review)

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 13 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole Near-horizon geometry of the extremal Kerr black hole

Extremal Kerr black hole: a = m ⇐⇒ κ = 0 (degenerate horizon) 2 Near-horizon geometry of extremal 4D Kerr is similar to AdS2 × S geometry; it has has extended isometry group: SL(2, R) × U(1), instead of merely R × U(1) for Kerr metric [Bardeen & Horowitz, PRD 60, 104030 (1999)] Near-horizon geometry of extremal Kerr black hole is at the basis of the Kerr/CFT correspondence (see [Compère, LRR 20, 1 (2017)] for a review)

Let us explore this geometry with a SageMath notebook: https://nbviewer.jupyter.org/github/sagemanifolds/SageManifolds/ blob/master/Notebooks/SM_extremal_Kerr_near_horizon.ipynb In the nbviewer menu, click on the icon to run an interactive version on a Binder server.

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 13 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 14 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 15 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 16 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 17 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 18 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 19 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 20 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 21 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 22 / 25 Example 2: near-horizon geometry of the extremal Kerr black hole

The full notebook is available at https://nbviewer.jupyter.org/github/sagemanifolds/SageManifolds/ blob/master/Notebooks/SM_extremal_Kerr_near_horizon.ipynb (in the nbviewer menu, click on the icon to run an interactive version on a Binder server)

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 23 / 25 Conclusions Outline

1 Differential geometry with SageMath

2 Example 1: black branes in 5D Lifshitz-like spacetimes

3 Example 2: near-horizon geometry of the extremal Kerr black hole

4 Conclusions

E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 24 / 25 Conclusions Conclusions

Many explicit computations on spacetimes of interest for the gauge/gravity duality can be performed with SageMath. More examples at https://sagemanifolds.obspm.fr/examples.html in particular the AdS spacetime example, exploring various coordinate systems, with many 3D plots: https://nbviewer.jupyter.org/github/sagemanifolds/SageManifolds/ blob/master/Notebooks/SM_anti_de_Sitter.ipynb

Want to join the SageManifolds project or simply to stay tuned? visit https://sagemanifolds.obspm.fr/ (download, documentation, example notebooks, mailing list) E. Gourgoulhon (LUTH) Holographic computations with SageMath APC, Paris, 27 Nov. 2019 25 / 25