One acceleration measurement equals ~10^5 phase-space measurements for local dark matter density estimation, with acceleration outperforming Jeans modeling in both equilibrium and perturbed Milky Way simulations.
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galpy: A Python Library for Galactic Dynamics
Tool reference. 88% of classified Pith citations use this work as a method, library, or software dependency, not as a substantive claim.
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88% of classified citations
abstract
I describe the design, implementation, and usage of galpy, a Python package for galactic-dynamics calculations. At its core, galpy consists of a general framework for representing galactic potentials both in Python and in C (for accelerated computations); galpy functions, objects, and methods can generally take arbitrary combinations of these as arguments. Numerical orbit integration is supported with a variety of Runge-Kutta-type and symplectic integrators. For planar orbits, integration of the phase-space volume is also possible. galpy supports the calculation of action-angle coordinates and orbital frequencies for a given phase-space point for general spherical potentials, using state-of-the-art numerical approximations for axisymmetric potentials, and making use of a recent general approximation for any static potential. A number of different distribution functions (DFs) are also included in the current release; currently these consist of two-dimensional axisymmetric and non-axisymmetric disk DFs, a three-dimensional disk DF, and a DF framework for tidal streams. I provide several examples to illustrate the use of the code. I present a simple model for the Milky Way's gravitational potential consistent with the latest observations. I also numerically calculate the Oort functions for different tracer populations of stars and compare it to a new analytical approximation. Additionally, I characterize the response of a kinematically-warm disk to an elliptical m=2 perturbation in detail. Overall, galpy consists of about 54,000 lines, including 23,000 lines of code in the module, 11,000 lines of test code, and about 20,000 lines of documentation. The test suite covers 99.6% of the code. galpy is available at http://github.com/jobovy/galpy with extensive documentation available at http://galpy.readthedocs.org/en/latest .
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representative citing papers
A 6D kinematic census identifies 18 anomalous Cepheids with extreme orbits, including one possibly scattered by globular cluster E3, and finds consistency between dynamical and stellar ages.
A data-driven decomposition of stellar abundance vectors into four latent patterns identifies distinct contributions from core-collapse supernovae, Type Ia supernovae, and AGB stars across the Milky Way disc.
Stellar streams encode the initial mass function of globular clusters, recovered as a declining power-law with slope 1.3 for streams above 1000 solar masses.
Blue straggler stars in old open clusters exhibit a Kraft break in rotation, with rapid rotators above the break and slow rotators below, indicating their envelopes behave like those of single stars.
Severe gas expulsion and expansion in a primordial star cluster, combined with a top-heavy IMF, can reproduce the high velocity dispersion and broad stream of C-19 without dark matter subhalos.
DESI-HVS1 is the first reported old, low-mass, metal-poor hypervelocity star candidate whose reconstructed orbit points to a Galactic Center origin.
A PINN approach learns galactic gravitational potentials from acceleration data, achieving sub-percent errors on simulations while outperforming analytic models and retaining interpretability via structured priors.
Koposov 2 is shown to be an old (13.7 Gyr) star cluster with half-light radius 2.7 pc, absolute magnitude -0.95, and stellar mass 372 solar masses, supporting a star cluster classification over a dwarf galaxy.
A complete classification of Gaia-selected hypervelocity candidates yields 10 D6 and 3 LP 40-365 stars, with forward modeling favoring intermediate-heating evolutionary scenarios and low birth rates relative to the SN Ia rate.
N-body simulations demonstrate runaway GW BBH mergers in dense BH clusters (≥5×10^9 M⊙/pc³) produce ~10³ M⊙ IMBHs within 10 Myr.
Empirical three-parameter fit to f_esc(M_h,z) yields steep redshift evolution with population-averaged escape fraction rising from ~2% at z=5 to ~9% at z=12.
Reprojects abundances of 199k stars into 4 patterns, identifying enrichment pathways with strong chemo-spatial, age, and vertical correlations plus a transition at ~6 Gyr.
Hot Jupiter occurrence in the Galactic halo is low at ~0.13% with no significant difference between in-situ and accreted populations, well below disk rates.
Blue straggler stars in old open clusters predominantly appear near the terminal-age main sequence because mass transfer from asymptotic giant branch donors enriches their cores with helium.
IY Lyr is a thick-disk RRc star with a 1.37 solar-mass companion most likely a neutron star in a 3.94-year eccentric orbit, confirmed by photometry, spectroscopy, and astrometry.
The Milky Way stellar disk shows a broken radial density profile with four components, azimuthal dependence, inner and outer flaring, and a density-metallicity bump possibly from radial migration.
The Gaia-Sausage-Enceladus merger occurred 11.2 ± 0.1 Gyr ago, coinciding with the formation of a group of globular clusters and potentially leaving ω Centauri as its remnant, while placing disk formation at z ≳ 4.
300S stellar stream exhibits three density peaks, smooth width variations, a possible 4.7 degree gap, and a kink modeled as resulting from Large Magellanic Cloud interaction across its full known footprint.
Simulations show Lindblad-resonance wrinkles from non-winding spirals are filled with zero-age stars on orbits normally occupied by much older populations, offering an age-based constraint on past transient spiral patterns.
Generates and publicly releases 81,498 detrended Kepler light curves plus a catalog of 87 periodic variables (26 new) in the 2.5 Gyr cluster NGC 6819 using Gaia DR3 for membership.
Test-particle simulations show that Galactic bar pattern speed systematically deflects open-cluster tidal tail orientations, with NGC 2632 and Hyades tails disfavouring moderate speeds.
A blind 12D chemo-dynamical clustering analysis with UMAP and HDBSCAN on SDSS-V DR19 and Gaia DR3 data recovers seven known halo substructures and reports five new tightly bound candidates FO1-FO5.
A lithium chemical evolution model for the GSE galaxy matches survey data showing Spite-like and eRGB plateaus at low metallicity with a hint of reduced nova contributions.
citing papers explorer
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Constraints on Einstein-aether gravity from the precision timing of PSR J1738+0333
Precision timing of PSR J1738+0333 from EPTA and NANOGrav data yields the tightest strong-field constraints on Einstein-aether parameters from any single binary pulsar.