galax

Galactic and Gravitational Dynamics

Installation

pip install galax

Documentation

Coming soon. In the meantime, if you've used gala, then galax should be familiar!

Quick example

Let's compute an orbit!

import jax.numpy as jnp

import unxt as u
import coordinax as cx
import galax.coordinates as gc
import galax.dynamics as gd
import galax.potential as gp

w = gc.PhaseSpaceCoordinate(
    q=u.Quantity([8, 0, 0], "kpc"),
    p=u.Quantity([0, 220, 0], "km/s"),
    t=u.Quantity(0, "Myr"),
)

pot = gp.MilkyWayPotential()

orbit = gd.evaluate_orbit(pot, w, u.Quantity(jnp.linspace(0, 1, 100), "Gyr"))
print(orbit)
# Orbit(
#     q=<CartesianPos3D: (x, y, z) [kpc]
#         [[ 8.     0.     0.   ]
#          ...
#          [ 7.804 -0.106  0.   ]]>,
#     p=<CartesianVel3D: (x, y, z) [kpc / Myr]
#         [[ 0.     0.225  0.   ]
#          ...
#          [ 0.018  0.23   0.   ]]>,
#     t=Quantity(Array([0., ..., 1000.], dtype=float64), unit='Myr')
# )

orbit_sph = orbit.vconvert(cx.vecs.LonLatSphericalPos)
print(orbit_sph)
# Orbit(
#     q=<LonLatSphericalPos: (lon[rad], lat[deg], distance[kpc])
#         [[0.000e+00 3.858e-16 8.000e+00]
#          ...
#          [6.270e+00 3.858e-16 7.805e+00]]>,
#     p=<LonLatSphericalVelocity (lon[rad / Myr], lat[deg / Myr], distance[kpc / Myr])
#         [[ 0.028  0.     0.   ]
#          ...
#          [ 0.03   0.     0.015]]>,
#     t=Quantity(Array([0., ..., 1000.], dtype=float64), unit='Myr')
# )

Citation

If you found this library to be useful in academic work, then please cite.

Development

We welcome contributions!

Galax uses uv for development dependency management (make sure you have uv version >=0.4.27 installed). For example, to run the test suite, install the test group and run pytest with:

uv sync --group test
uv run pytest src docs tests

Contributors

See the AUTHORS.rst file for a complete list of contributors to the project.

The GalacticDynamics/galax maintainers would like to thank @Michael Anckaert for transferring the galax project domain on PyPI for use by this package. Without his generosity this package would have had a worse name.