UF23 Galactic Magnetic Field Models

C++ implementation of Galactic Magnetic Field models from the paper The Coherent Magnetic Field of the Milky Way by Michael Unger and Glennys R. Farrar.

Usage

To calculate the magnetic field of the models, only the code implemented in the UF23Field class is needed. E.g., the magnetic field of the base model at a certain position can be obtained as

const UF23Field uf23Field(UF23Field::base);
const Vector3 position(1, 3, 2);
const auto field = uf23Field(position);
cout << field.x << " " << field.y << " " << field.z << endl;

Here the constructor takes an argument specifying one of the eight UF23 models (base, cre10, expX, neCL, nebCor, spur, synCG or twistX). The position is given in Cartesian galacto-centric coordinates in units of kpc (Earth at negative x, North at positive z). The output magnetic field vector is again in Cartesian galacto-centric coordinates, the unit of its components is μG (micro-Gauss).

Example programs

Type

make

to compile two simple example programs. Then type e.g.

./calcUF23Field base 1 3 2

to obtain the following output:

(x,y,z)    = (1.0000e+00, 3.0000e+00, 2.0000e+00) kpc
(bx,by,bz) = (-1.7697e+00, 8.5706e-01, 6.6356e-01) microgauss

Note: this is just a test program. If many evaluations are needed it is very inefficient to execute the calcUF23Field program repeatedly due to the overhead of initialization. For that case it is better to implement a loop over positions inside the code.

Another example program called sampleUF23Field illustrates the sampling of parameter uncertainties for advanced users.

For further technical tests, run

make test

License

Released under BSD 2-Clause "Simplified" License.

Please cite Unger and Farrar (2024) if you find this code useful in your research. The BibTeX entry for the paper is:

@article{UngerFarrar2023,
    author = "Unger, Michael and Farrar, Glennys R.",
    title = "{The Coherent Magnetic Field of the Milky Way}",
    eprint = "2311.12120",
    archivePrefix = "arXiv",
    primaryClass = "astro-ph.GA",
    doi = "10.3847/1538-4357/ad4a54",
    journal = "Astrophys. J.",
    volume = "970",
    number = "1",
    pages = "95",
    year = "2024"
}