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OTI on FIRE: Testing the Efficacy of Orbital Torus Imaging to Recover the Galactic Potential

T0 review · 3 major / 5 minor · reviewed 2026-08-15 · deepseek-v4-flash

Pith's one-line read Run on a realistic, out-of-equilibrium simulated galaxy, Orbital Torus Imaging recovers the true vertical acceleration within $3\sigma$ for 15 of 16 solar-analog volumes and within $1\sigma$ for 12 of 16.

desk verdict Useful FIRE-2 benchmark for OTI, but the 94%/75% recovery fractions lean on precision-only error bars the authors themselves flag as incomplete. read the letter →

arxiv 2505.05590 v1 pith:ZTZ4LGPS submitted 2025-05-08 astro-ph.GA astro-ph.IMastro-ph.SR

classification astro-ph.GAastro-ph.IMastro-ph.SR
keywords OrbitalTorusImagingGalacticpotentialverticalaccelerationFIRE-2simulationdisequilibriummetallicitygradientsurfacemassdensityMilkyWaydisk
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

Orbital Torus Imaging (OTI) infers a galaxy's gravitational potential from the way a stellar label, here the mean iron abundance $\langle\mathrm{[Fe/H]}\rangle$, is arranged in the vertical phase space of height $z$ and vertical velocity $v_z$, without fitting a parametric potential or integrating orbits. The paper asks whether this steady-state machinery still works in a galaxy that is obviously not in equilibrium, the situation the Milky Way is actually in, and answers by running OTI on the FIRE-2 cosmological simulation m12i, whose true vertical accelerations are stored. It finds that OTI recovers the simulated acceleration profiles within $3\sigma$ for 15 of 16 and within $1\sigma$ for 12 of 16 solar-analog volumes, and that its estimates are roughly 85% more precise than Jeans modeling on the same data. Accuracy degrades in volumes with thick, old, kinematically heated stellar populations, pointing to the model's load-bearing assumption that vertical and radial motions decouple.

What carries the argument

The engine of the method is the vertical metallicity gradient: stars near the midplane carry higher $\langle\mathrm{[Fe/H]}\rangle$ than stars at large $|z|$, so contours of constant mean abundance in the $(z, v_z)$ plane outline the shapes of stellar orbits. OTI parameterizes those contours as ellipses distorted by $m = 2$ and $m = 4$ Fourier terms whose coefficients are splines of a proxy vertical action $r_z$, fits the 26-parameter model to binned abundance data by gradient descent through automatic differentiation, and then reads the vertical acceleration $a_z$ off the best-fit orbital shapes through the one-dimensional vertical collisionless Boltzmann equation with the radial term dropped. The proxy-action splines carry the argument: they let the model represent the transition from elliptical orbits near the midplane to pinched, diamond-like orbits at large heights without ever committing to a parameterized mass model, which is why the technique is insensitive to the selection function.

What would settle it

Re-run the analysis on the four volumes that missed the $1\sigma$ threshold (V2, V13, V14, V16) using only stars with $|z| < 1.5$ kpc. The paper's own explanation predicts these volumes should then agree within $3\sigma$; if they still disagree, the proposed failure mechanism, breakdown of vertical-radial separability, is wrong.

Watch

Extended reading notes

Core claim

The paper's central claim is that OTI, despite assuming axisymmetry and steady state, recovers the true vertical acceleration profile of a realistic Milky-Way-mass galaxy that is out of equilibrium. Across 16 solar-analog volumes at $R = 8$ kpc, the inferred $a_z$ matches the simulation's stored acceleration within $3\sigma$ in 15 volumes and within $1\sigma$ in 12, and the total surface mass density at $z = 1.1$ kpc agrees within $3\sigma$ in the same 15 volumes. The method's failures concentrate in the volumes with the largest scale heights (above roughly 1.5 kpc) and oldest stars, exactly where the assumed separability of vertical and radial motion breaks down; notably, vertical asymmetry of the density distribution does not hurt accuracy. A previously published OTI estimate of the Milky Way's surface mass density at $z = 1.1$ kpc falls squarely within the range of true simulated values, which the authors take as evidence that the method can be trusted on real survey data.

Load-bearing premise

The method assumes a star's up-down motion is independent of its in-plane motion, which holds only for stars on nearly circular, dynamically cold orbits and fails at heights above roughly 1.5 kpc.

Editorial extensions

If this is right

  • OTI can be applied to Milky Way-like disks that are mildly out of equilibrium, with a quantified error budget: 94% of volumes within $3\sigma$ and 75% within $1\sigma$ for the vertical acceleration, and the same 94% for the surface mass density at $z = 1.1$ kpc.
  • The Milky Way's OTI-inferred surface mass density from earlier work lands inside the range of true FIRE-2 values, so existing OTI-based Galactic constraints gain an independent plausibility check.
  • With uncertainties from MCMC sampling and bootstrapping, OTI's vertical acceleration estimates are about 85% more precise than Jeans modeling, making it the sharper tool for mapping the disk's vertical mass profile.
  • OTI is most trustworthy in thin, dense, young volumes; regions with scale heights above about 1.5 kpc or old stellar populations should be flagged before interpreting their inferred potentials.
  • The error bars derived from the simulation establish a touchstone for interpreting results from current and forthcoming surveys such as SDSS-V, Gaia, WEAVE, and 4MOST.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The four volumes that miss the $1\sigma$ bar (V2, V13, V14, V16) are precisely those with large scale heights and old median ages, so a cheap pre-analysis cut on those two observables could flag survey volumes where OTI results are likely biased before any potential fitting is done.
  • The residual pattern the paper reports, overpredicting $a_z$ above the midplane and underpredicting it below by about 15%, is a coherent fingerprint of the dropped radial term; if the same antisymmetric signature appears in real Milky Way data, it would identify the separability approximation, not measurement noise, as the limiting error.
  • Because the paper finds that vertical asymmetry barely affects accuracy, OTI may be resilient to the warps and breathing modes the Milky Way is currently experiencing; this resilience is testable directly by running the same protocol on mock Gaia-like catalogs drawn from other FIRE-2 snapshots.
  • The natural stress test is to repeat the 16-volume protocol on FIRE-2 galaxies that have undergone recent mergers; recovery fractions falling well below 94% would map out how much disequilibrium OTI can tolerate and where it should not be trusted.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 5 minor

Summary. This paper benchmarks the Orbital Torus Imaging (OTI) method on the FIRE-2 cosmological zoom-in simulation m12i. The authors select 16 solar-analog volumes at R = 8 kpc, fit OTI models to the binned mean [Fe/H] distribution in (z, vz) vertical phase space, and compare the inferred vertical acceleration profiles and total surface mass densities at z = 1.1 kpc against the accelerations and densities stored in the simulation. They report that the OTI-inferred az profiles match the known FIRE-2 profiles within 3σ for 15/16 volumes and within 1σ for 12/16 volumes, and that Σ☉(z = 1.1 kpc) agrees within 3σ for 15/16 volumes. The paper also compares OTI precision with Jeans modeling, identifies volume properties (scale height, median stellar age, surface density) that correlate with fit quality, and discusses implications of OTI for distinguishing dark matter models.

Significance. If the headline recovery fractions were supported by a complete error budget, this would be a valuable validation of OTI in a realistic, live, out-of-equilibrium simulated disk. The comparison is genuinely external: the FIRE-2 stored accelerations played no role in the OTI fit, so the benchmark is not circular. The use of 16 spatially separated volumes within one cosmological simulation is a meaningful step beyond the earlier single-volume N-body test, and the authors are commendably transparent about their assumptions and residual trends. However, the central quantitative claim currently rests on an error budget that the authors themselves state excludes model inaccuracies, and the paper's own Figure 7 shows a systematic residual pattern. The significance of the result is therefore conditional on re-framing or supplementing the uncertainty assessment.

major comments (3)
  1. [§5.1, Figure 6, and abstract] The central claim that OTI recovers the true vertical acceleration 'within 3σ/1σ for 94%/75% of volumes' is not supported by the quoted uncertainties. The errors shown in Figure 6 combine MCMC sampling and bootstrap resampling only. The text in §5.1 explicitly states that this combined uncertainty 'reflects the precision of our measurement but not model inaccuracies' and that OTI's symmetry assumptions are violated in m12i. Since the true FIRE-2 profiles are known, the appropriate accuracy statement would use a total error budget that includes model misspecification, or report residuals directly. Figure 7 shows a systematic trend: OTI overpredicts above the midplane and underpredicts below it, with median percent differences of 15% and 14%. With a precision-only σ, the 15/16 and 12/16 counts measure whether the precision error bars happen to cover the true profile, not whether the method is accurately recovering it. The abstract and conclusions should be revised to either quote residual-based accuracy metrics or to explicitly qualify the σ as precision-only, ideally with an added systematic component.
  2. [§7, first bullet] The argument that '12/16 within 1σ is almost what we observe' (expected 11/16 under pure statistical errors) is circular. The expected count of 11/16 is derived from the same incomplete σ that defines the observed count, so the near-agreement between expectation and observation carries no information about whether systematic errors dominate. A meaningful test would compare the observed residuals to a σ that includes model error, or would compare the magnitude of the systematic residual to the statistical precision independently. As written, this bullet over-interprets the agreement between an observation and an expectation that were constructed from the same input.
  3. [§3, §4.1, and Figure 6, volumes V13/V14] The paper's own model assumptions are acknowledged to break down in precisely the regimes where the failures occur: R–z separability and neglect of the radial term of the collisionless Boltzmann equation 'may not be valid for regions far (|z| ≥ 1.5 kpc) from the midplane' (footnote in §3), and §4.1 restricts the analysis accordingly. Volumes V13 and V14, which have the largest scale heights and oldest, kinematically heated populations, are the ones with the worst recovery, consistent with this misspecification. Because the model error from separability is not quantified, the reader cannot tell how much of the recovery success in the other volumes is due to the method working versus the volumes being close enough to the thin-disk regime that the misspecification is small. The authors should add a sensitivity test or comparable systematic-error estimate that varies the model assumptions (e.g., including the radial term or fitting a non-separable model) and report how the recovery fractions change.
minor comments (5)
  1. [§3, first paragraph] There is a typo: 'We employ the the 1D vertical collisionless Boltzmann equation' should read 'We employ the 1D vertical collisionless Boltzmann equation'.
  2. [§5.1, paragraph after Figure 6] The statement that OTI provides a more precise az estimate 'by ~85% across the disk' is not defined precisely: it is unclear whether this is the median ratio of Jeans to OTI error bars, averaged over z, or computed in some other way. A brief definition of the metric would improve reproducibility.
  3. [§4.2 and Appendix D] The 26 free parameters are listed, but the bounds and priors used in the MCMC sampling are not given. For a paper whose headline is about uncertainty quantification, specifying the priors and the chain convergence checks (e.g., R-hat, effective sample size) would be important for reproducibility.
  4. [§6, Figure 9] The Pearson correlation coefficients are reported to two decimals, but no significance or confidence intervals are given. Given only 16 volumes, reporting p-values or bootstrap confidence intervals on r would help the reader judge whether the claimed weak/moderate correlations are meaningful.
  5. [§1 and §2] The phrase 'recently quiescent' is used for m12i, but the quantitative definition is deferred to a citation. Stating the last major merger time and the current snapshot time explicitly would make the 'dynamically-evolving' context easier to interpret.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the OTI-inferred vertical acceleration is benchmarked against FIRE-2 stored accelerations that play no role in the fit.

full rationale

The OTI model is fit exclusively to binned mean-metallicity data in each of 16 solar-analog volumes, as described in Sections 4.1 and 4.2; no FIRE-2 acceleration value enters the likelihood, the optimization, or the MCMC and bootstrap error estimation. The ground-truth vertical acceleration used for validation is FIRE-2's stored particle acceleration, which the paper explicitly identifies as an independent quantity: 'The particle accelerations used for comparison with the OTI inferences are a stored quantity for Latte galaxies' (Section 2). Figure 6 is therefore an external benchmark rather than a fitted-input prediction. The method's assumptions (axisymmetry, steady-state, R-z separability, neglect of the radial collisionless Boltzmann term) are imported from Price-Whelan et al. (2025) through self-citations, but this import is not circular in the present paper because the new content is precisely a test of those assumptions against an independent simulation. The paper also explicitly concedes that the quoted uncertainty 'reflects the precision of our measurement but not model inaccuracies' and that OTI 'assumes a symmetric distribution, an assumption which is violated in a realistic simulated galaxy, m12i' (Section 5.1). This is an honest limitation and a statistical-correctness caveat, not a circular derivation: the 94%/75% recovery fractions may overstate accuracy because model error is excluded, but they do not reduce to the inputs of the fit. No equation is shown to be equivalent to its own input by construction, and no fitted parameter is renamed as a prediction. The only circularity-adjacent feature is that the method papers and the torusimaging package originate from coauthors, but the load-bearing comparison is to an external, independently stored simulation quantity, so this self-citation is not load-bearing.

Assumptions & free parameters 7 free parameters · 6 assumptions · 0 invented entities

The paper fits 26 OTI parameters per volume (spline knots, Fourier distortion knots, centroid, midplane frequency) plus hand-chosen hyperparameters and data-dependent bin extents; the vertical acceleration is derived from those fits, not measured directly. It relies on the steady-state, axisymmetric, R-z separable, phase-mixed assumptions of OTI, several of which are violated in m12i and are explicitly acknowledged. No new physical entities are introduced. The validation against FIRE-2 stored accelerations is the main external anchor.

free parameters (7)
  • OTI label spline knots (8 per volume, 16 volumes) = not tabulated
    The mean [Fe/H] as a function of the proxy vertical action is a monotonic quadratic spline with 8 knots, fit to simulated abundance data in every volume; the inferred az depends directly on this fitted label function (Section 4.2, Table 1).
  • e2 Fourier distortion spline knots (10 per volume, 16 volumes) = not tabulated
    The m=2 orbital shape distortion in the vertical phase plane is fit per volume; it controls the contour shapes from which az is computed (Section 4.2).
  • e4 Fourier distortion spline knots (5 per volume, 16 volumes) = not tabulated
    The m=4 orbital shape distortion is fit per volume; it refines the contour model entering the az inference (Section 4.2).
  • Centroid (z0, vz0) per volume = not tabulated
    The phase-space centroid of the mean abundance distribution is fit per volume; torusimaging recenters the midplane using this, which mitigates vertical asymmetry but directly shifts the az comparison (Section 4.2, Appendix B).
  • Midplane orbital frequency Omega0 per volume = not tabulated
    An asymptotic midplane orbital frequency parameter of the OTI model, fit per volume and entering the az computation (Section 4.2).
  • OTI hyperparameters (nknots, L2 regularization, smoothing, spacing power) = nknots=8/10/5; L2=1.0; smoothing=0.5/0.1/0.1; spacing power=0.75
    Hand-chosen model settings from Table 1. The accuracy fractions and az profiles depend on these choices, though they are not fit to the FIRE-2 az truth.
  • zmax and vzmax bin extents per volume = zmax 3.0-3.7 kpc; vzmax 139-154 km/s
    Binning limits derived from 3 x 1.5 x MAD of z and vz in each volume; they set the data range over which the OTI model is fit and therefore affect the inferred az (Section 4.1).
assumptions (6)
  • domain assumption The stellar distribution function is in steady state and phase-mixed
    Stated in Section 3 as an OTI assumption: equilibrium and phase-mixing. m12i violates this locally, and the paper's inference still mostly succeeds; if violated strongly, az is biased.
  • domain assumption The gravitational potential is axisymmetric
    OTI assumes axisymmetry (Section 3). m12i contains a bar and spiral arms, so the assumption is approximate; the method's robustness to this approximation is part of what is tested.
  • domain assumption Vertical and radial motions decouple; R-z separability and the radial term in the collisionless Boltzmann equation are neglected
    The paper explicitly drops the radial term and notes the approximation may fail for |z| >= 1.5 kpc (Section 3 footnote, Section 4.1). This is the main structural fragility for thick, kinematically heated stellar populations.
  • domain assumption The mean [Fe/H] is a function only of orbital invariants and carries no explicit orbital-phase dependence
    This is the core OTI mapping from abundance contours to orbital shapes (Section 3 and Price-Whelan et al. 2025). If abundance gradients are not phase-mixed, the contour fit misrepresents the orbit structure.
  • domain assumption FIRE-2 m12i is a representative testbed for Milky Way-like disequilibrium conditions
    The paper selects m12i because it is recently quiescent (Section 2). The quantitative accuracy fractions are specific to this one simulated galaxy and may not generalize to strongly perturbed systems.
  • domain assumption The MCMC plus bootstrap variance is treated as the total uncertainty for the sigma-agreement claims
    Used to define 1-sigma and 3-sigma agreement in Figures 6 and 8. The paper states this uncertainty is underestimated because it excludes model inaccuracies (Section 5.1).

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Cite this review

Pith. "Pith review of OTI on FIRE: Testing the Efficacy of Orbital Torus Imaging to Recover the Galactic Potential." pith.science (2026). https://pith.science/paper/ZTZ4LGPS

@misc{pith2026250505590,
  author       = {Pith},
  title        = {Pith review of: OTI on FIRE: Testing the Efficacy of Orbital Torus Imaging to Recover the Galactic Potential},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/ZTZ4LGPS}},
  note         = {Machine review of arXiv:2505.05590}
}
read the original abstract

Orbital Torus Imaging (OTI) is a dynamical inference method for determining the Milky Way's gravitational potential using stellar survey data. OTI uses gradients in stellar astrophysical quantities, such as element abundances, as functions of dynamical quantities, like orbital actions or energy, to estimate the Galactic mass distribution, assuming axisymmetry and steady-state of the system. While preliminary applications have shown promising outcomes, its sensitivity to disequilibrium effects is unknown. Here, we apply OTI to a benchmark Feedback in Realistic Environments (FIRE-2) cosmological hydrodynamic simulation, m12i, which enables a comparative analysis between known FIRE-2 vertical acceleration profiles and total surface mass densities to the analogous OTI-inferred results. We quantify OTI's accuracy within solar-analog volumes embedded in the simulated galactic disk. Despite a dynamically-evolving system, we find that OTI recovers the known vertical acceleration profiles within 3 sigma/1 sigma errors for 94%/75% of the volumes considered. We discuss the method's sensitivity to the local, instantaneous structure of the disk, reporting a loss in accuracy for volumes that have large (>1.5 kpc) scale heights and low total density at z=1.1 kpc. We present realistic OTI error bars from both MCMC sampling and bootstrapping the FIRE-2 simulated data, which provides a touchstone for interpreting results obtained from current and forthcoming surveys such as SDSS-V, Gaia, WEAVE, and 4MOST.

Figures

Figures reproduced from arXiv: 2505.05590 by the authors.

Figure 1
Figure 1. Selecting volumes of stars across the disk and analyzing within individual volumes enables us to explore how diverse disk environments impact OTI inferences. Left: The background displays stellar surface mass density for FIRE-2 simulated galaxy, m12i, at present-day. In the foreground, we plot open, colored circles indicating 16 solar-analog volumes, each centered at a galactocentric radius of 8 kpc, with a radius o… view at source ↗
Figure 2
Figure 2. Asymmetric global stellar kinematic conditions are present at present-day in m12i: violet and blue lobes near the solar annulus emphasize variations in stellar velocities. Top: A top-down view of the mean stellar radial velocity. Colored circles mark the solar regions shown in [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 4
Figure 4. [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗
Figures from the paper (5 more)
Figure 5
Figure 5. Figure 5: The OTI model reliably captures the known FIRE-2 ⟨[Fe/H]⟩ distribution with nonsystematic residuals. Left: 2D histogram of the ⟨[Fe/H]⟩ abundance from Volume 1 (V1) in m12i at present-day, in bins ranging from 170 to 226 (pc * km s −1 ), as in [PITH_FULL_IMAGE:figures…
Figure 6
Figure 6. Figure 6: The OTI model accurately recovers the true vertical acceleration profile within 3σ for 15 out of 16 solar volumes (all but V14) and within 1σ for 12 out of 16 solar volumes (all but V2, V13, V14, and V16) in m12i. The black solid line represents FIRE-2 simulated galaxy…
Figure 7
Figure 7. Figure 7: The median (across all 16 volumes) normalized residual profile shows the OTI model achieves reasonable accuracy in recovering FIRE-2 az profiles. We also plot 1σ (light shaded region from the median, and 1.5 × MAD (darker shaded region). This provides an estimate of th…
Figure 8
Figure 8. Figure 8: OTI estimates agree with FIRE-2 true values for total surface mass density at z=1.1 kpc within 3σ except for V14. Total surface mass density for FIRE (star symbols) and OTI (circle symbols) is shown with 1σ and 3σ error bars at |z|=1.1 kpc. The gray-shaded panel indica…
Figure 9
Figure 9. Figure 9: Vertical asymmetry (left) and slope of the metallicity gradient (middle left) have weak correlations with the goodness￾of-fit, χ 2 , normalized by θ, the total number of parameters, while total density (middle right), median age (right), and scale height moderately cor…

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Works this paper leans on

116 extracted references · 7 canonical work pages

  1. [1]

    , " * write output.state after.block = add.period write newline

    ENTRY address archivePrefix author booktitle chapter doi edition editor eprint howpublished institution journal key month number organization pages publisher school series title misctitle type volume year version url label extra.label sort.label short.list INTEGERS output.state before.all mid.sentence after.sentence after.block FUNCTION init.state.consts ...

  2. [2]

    write newline

    " write newline "" before.all 'output.state := FUNCTION format.url url empty "" new.block "" url * "" * if FUNCTION format.eprint eprint empty "" archivePrefix empty "" archivePrefix "arXiv" = new.block " " eprint * " " * new.block " " eprint * " " * if if if FUNCTION format.doi doi empty "" " " doi * " " * if FUNCTION format.pid doi empty eprint empty ur...

  3. [3]

    w po [Am۶׿ 5*& qRC&kdaVIIIƍ - r°, |殺pbt o 3f.c2 lbdc*'YU- ) Ι3'֐ G^

    thebibliography [1] 20pt to REFERENCES 6pt =0pt -12pt 10pt plus 3pt =0pt =0pt =1pt plus 1pt =0pt =0pt -12pt =13pt plus 1pt =20pt =13pt plus 1pt \@M =10000 =-1.0em =0pt =0pt 0pt =0pt =1.0em @enumiv\@empty 10000 10000 `\.\@m \@noitemerr \@latex@warning Empty `thebibliography' environment \@ifnextchar \@reference \@latexerr Missing key on reference command E...

  4. [4]

    G., Navarro , J

    Abadi , M. G., Navarro , J. F., Steinmetz , M., & Eke , V. R. 2003, , 597, 21, 10.1086/378316

  5. [5]

    E., et al

    Ansar , S., Pearson , S., Sanderson , R. E., et al. 2025, , 978, 37, 10.3847/1538-4357/ad8b45

  6. [6]

    2018, , 561, 360, 10.1038/s41586-018-0510-7

    Antoja , T., Helmi , A., Romero-G \'o mez , M., et al. 2018, , 561, 360, 10.1038/s41586-018-0510-7

  7. [7]

    E., Panithanpaisal , N., et al

    Arora , A., Sanderson , R. E., Panithanpaisal , N., et al. 2022, , 939, 2, 10.3847/1538-4357/ac93fb

  8. [8]

    2024 a , , 977, 23, 10.3847/1538-4357/ad88f0

    Arora , A., Sanderson , R., Regan , C., et al. 2024 a , , 977, 23, 10.3847/1538-4357/ad88f0

Show all 116 references
  1. [9]

    E., Chakrabarti , S., et al

    Arora , A., Sanderson , R. E., Chakrabarti , S., et al. 2024 b , , 974, 223, 10.3847/1538-4357/ad71c4

  2. [10]

    E., et al

    Arora, A., Garavito-Camargo, N., Sanderson, R. E., et al. 2025, arXiv e-prints. arXiv:2504.20133

  3. [11]

    J., & Scott , P

    Asplund , M., Grevesse , N., Sauval , A. J., & Scott , P. 2009, , 47, 481, 10.1146/annurev.astro.46.060407.145222

  4. [12]

    M., Sip o cz , B

    Astropy Collaboration , Price-Whelan , A. M., Sip o cz , B. M., et al. 2018, , 156, 123, 10.3847/1538-3881/aabc4f

  5. [13]

    Bahcall , J. N. 1984, , 287, 926, 10.1086/162750

  6. [14]

    N., & Soneira , R

    Bahcall , J. N., & Soneira , R. M. 1980, , 44, 73, 10.1086/190685

  7. [15]

    2022, Symmetry, 14, 1331, 10.3390/sym14071331

    Banik , I., & Zhao , H. 2022, Symmetry, 14, 1331, 10.3390/sym14071331

  8. [16]

    C., Flynn , K., & Gebhardt , K

    Beers , T. C., Flynn , K., & Gebhardt , K. 1990, , 100, 32, 10.1086/115487

  9. [17]

    A., Wetzel , A., Loebman , S

    Bellardini , M. A., Wetzel , A., Loebman , S. R., & Bailin , J. 2022, , 10.1093/mnras/stac1637

  10. [18]

    A., Wetzel , A., Loebman , S

    Bellardini , M. A., Wetzel , A., Loebman , S. R., et al. 2021, , 505, 4586, 10.1093/mnras/stab1606

  11. [19]

    B., Evans , N

    Belokurov , V., Zucker , D. B., Evans , N. W., et al. 2006, , 642, L137, 10.1086/504797

  12. [20]

    Bennett , M., Bovy , J., & Hunt , J. A. S. 2022, , 927, 131, 10.3847/1538-4357/ac5021

  13. [21]

    R., Ness , M

    Bhattarai , B., Loebman , S. R., Ness , M. K., et al. 2024, , 977, 70, 10.3847/1538-4357/ad8bac

  14. [22]

    C., Salomon , J

    Bienaym \'e , O., Robin , A. C., Salomon , J. B., & Reyl \'e , C. 2024, , 689, A280, 10.1051/0004-6361/202450327

  15. [23]

    2014, , 571, A92, 10.1051/0004-6361/201424478

    Bienaym \'e , O., Famaey , B., Siebert , A., et al. 2014, , 571, A92, 10.1051/0004-6361/201424478

  16. [24]

    2008, Galactic Dynamics: Second Edition (Princeton University Press)

    Binney , J., & Tremaine , S. 2008, Galactic Dynamics: Second Edition (Princeton University Press). http://adsabs.harvard.edu/abs/2008gady.book.....B

  17. [25]

    C., Loebman , S

    Bird , J. C., Loebman , S. R., Weinberg , D. H., et al. 2021, , 503, 1815, 10.1093/mnras/stab289

  18. [26]

    F., & Kere s , D

    Bonaca , A., Conroy , C., Wetzel , A., Hopkins , P. F., & Kere s , D. 2017, , 845, 101, 10.3847/1538-4357/aa7d0c

  19. [27]

    1981, , 86, 1791, 10.1086/113062

    Bosma , A. 1981, , 86, 1791, 10.1086/113062

  20. [28]

    2015, , 216, 29, 10.1088/0067-0049/216/2/29

    Bovy , J. 2015, , 216, 29, 10.1088/0067-0049/216/2/29

  21. [29]

    2018, JAX: Composable Transformations of Python+NumPy Programs, 0.3.13

    Bradbury, J., Frostig, R., Hawkins, P., et al. 2018, JAX: Composable Transformations of Python+NumPy Programs, 0.3.13. http://github.com/google/jax

  22. [30]

    S., & Johnston , K

    Bullock , J. S., & Johnston , K. V. 2005, , 635, 931, 10.1086/497422

  23. [31]

    R., & Schutz, K

    Buschmann, M., Safdi, B. R., & Schutz, K. 2021, Phys. Rev. Lett., 127, 241104, 10.1103/PhysRevLett.127.241104

  24. [32]

    H., Lu , P., Nocedal , J., & Zhu , C

    Byrd , R. H., Lu , P., Nocedal , J., & Zhu , C. 1995, SIAM Journal on Scientific Computing, 16, 1190, 10.1137/0916069

  25. [33]

    2024, BlackJAX: Composable B ayesian inference in JAX

    Cabezas, A., Corenflos, A., Lao, J., & Louf, R. 2024, BlackJAX: Composable B ayesian inference in JAX . 2402.10797

  26. [34]

    2024, arXiv e-prints, arXiv:2402.10797, 10.48550/arXiv.2402.10797

    Cabezas , A., Corenflos , A., Lao , J., et al. 2024, arXiv e-prints, arXiv:2402.10797, 10.48550/arXiv.2402.10797

  27. [35]

    2012, , 144, 185, 10.1088/0004-6256/144/6/185

    Carrell , K., Chen , Y., & Zhao , G. 2012, , 144, 185, 10.1088/0004-6256/144/6/185

  28. [36]

    K., Hawkins , K., et al

    Carrillo , A., Ness , M. K., Hawkins , K., et al. 2023, , 942, 35, 10.3847/1538-4357/aca1c7

  29. [37]

    T., Vigeland , S

    Chakrabarti , S., Chang , P., Lam , M. T., Vigeland , S. J., & Quillen , A. C. 2021, , 907, L26, 10.3847/2041-8213/abd635

  30. [38]

    2020, The Astrophysical Journal, 902, L28, 10.3847/2041-8213/abb9b5

    Chakrabarti, S., Wright, J., Chang, P., et al. 2020, The Astrophysical Journal, 902, L28, 10.3847/2041-8213/abb9b5

  31. [39]

    Chiba , R., Friske , J. K. S., & Sch \"o nrich , R. 2021, , 500, 4710, 10.1093/mnras/staa3585

  32. [40]

    A., Schaye , J., Bower , R

    Crain , R. A., Schaye , J., Bower , R. G., et al. 2015, , 450, 1937, 10.1093/mnras/stv725

  33. [41]

    J., Belokurov , V., Evans , N

    Deason , A. J., Belokurov , V., Evans , N. W., & Johnston , K. V. 2013, , 763, 113, 10.1088/0004-637X/763/2/113

  34. [42]

    1998, , 294, 429, 10.1046/j.1365-8711.1998.01282.x10.1111/j.1365-8711.1998.01282.x

    Dehnen , W., & Binney , J. 1998, , 294, 429, 10.1046/j.1365-8711.1998.01282.x10.1111/j.1365-8711.1998.01282.x

  35. [43]

    M., et al

    Donlon , T., Chakrabarti , S., Widrow , L. M., et al. 2024, , 110, 023026, 10.1103/PhysRevD.110.023026

  36. [44]

    D'Souza , R., & Bell , E. F. 2022, , 512, 739, 10.1093/mnras/stac404

  37. [45]

    W., Rix , H.-W., & Ness , M

    Eilers , A.-C., Hogg , D. W., Rix , H.-W., & Ness , M. K. 2019, , 871, 120, 10.3847/1538-4357/aaf648

  38. [46]

    Faucher-Gigu \`e re , C.-A., Quataert , E., & Hopkins , P. F. 2013, , 433, 1970, 10.1093/mnras/stt866

  39. [47]

    Gaia Collaboration , Prusti , T., de Bruijne , J. H. J., et al. 2016, , 595, A1, 10.1051/0004-6361/201629272

  40. [48]

    Garavito-Camargo , N., Besla , G., Laporte , C. F. P., et al. 2019, , 884, 51, 10.3847/1538-4357/ab32eb

  41. [49]

    M., Samuel , J., et al

    Garavito-Camargo , N., Price-Whelan , A. M., Samuel , J., et al. 2024, , 975, 100, 10.3847/1538-4357/ad6e7e

  42. [50]

    I., & Lake , G

    Garbari , S., Liu , C., Read , J. I., & Lake , G. 2012, , 425, 1445, 10.1111/j.1365-2966.2012.21608.x

  43. [51]

    A., White , S

    G \'o mez , F. A., White , S. D. M., Marinacci , F., et al. 2016, , 456, 2779, 10.1093/mnras/stv2786

  44. [52]

    L., Wetzel , A., Bellardini , M

    Graf , R. L., Wetzel , A., Bellardini , M. A., & Bailin , J. 2025, , 981, 47, 10.3847/1538-4357/adacd7

  45. [53]

    Grand , R. J. J., G \'o mez , F. A., Marinacci , F., et al. 2017, , 467, 179, 10.1093/mnras/stx071

  46. [54]

    2020, , 495, 4828, 10.1093/mnras/staa1483

    Guo , R., Liu , C., Mao , S., et al. 2020, , 495, 4828, 10.1093/mnras/staa1483

  47. [55]

    B., Faucher-Gigu \`e re , C.-A., Richings , A

    Gurvich , A. B., Faucher-Gigu \`e re , C.-A., Richings , A. J., et al. 2020, , 498, 3664, 10.1093/mnras/staa2578

  48. [56]

    R., Millman , K

    Harris , C. R., Millman , K. J., van der Walt , S. J., et al. 2020, , 585, 357, 10.1038/s41586-020-2649-2

  49. [57]

    R., Holtzman , J

    Hayden , M. R., Holtzman , J. A., Bovy , J., et al. 2014, , 147, 116, 10.1088/0004-6256/147/5/116

  50. [58]

    H., et al

    Helmi, A., Babusiaux, C., Koppelman, H. H., et al. 2018, Nature, 563, 85, 10.1038/s41586-018-0625-x

  51. [59]

    Hopkins , P. F. 2015, , 450, 53, 10.1093/mnras/stv195

  52. [60]

    F., Wetzel , A., Kere s , D., et al

    Hopkins , P. F., Wetzel , A., Kere s , D., et al. 2018, , 480, 800, 10.1093/mnras/sty1690

  53. [61]

    M., Hogg , D

    Horta , D., Price-Whelan , A. M., Hogg , D. W., et al. 2024, , 962, 165, 10.3847/1538-4357/ad16e8

  54. [62]

    W., Yuan , H

    Huang , Y., Liu , X. W., Yuan , H. B., et al. 2016, , 463, 2623, 10.1093/mnras/stw2096

  55. [63]

    Hunt , J. A. S., Stelea , I. A., Johnston , K. V., et al. 2021, , 508, 1459, 10.1093/mnras/stab2580

  56. [64]

    Hunter, J. D. 2007, Computing in Science & Engineering, 9, 90, 10.1109/MCSE.2007.55

  57. [65]

    A., et al

    Imig , J., Price , C., Holtzman , J. A., et al. 2023, , 954, 124, 10.3847/1538-4357/ace9b8

  58. [66]

    2008, , 684, 287, 10.1086/589678

    Ivezi \'c , Z ., Sesar , B., Juri \'c , M., et al. 2008, , 684, 287, 10.1086/589678

  59. [67]

    Jeans , J. H. 1915, , 76, 70, 10.1093/mnras/76.2.70

  60. [68]

    1922, , 82, 122, 10.1093/mnras/82.3.122

    ---. 1922, , 82, 122, 10.1093/mnras/82.3.122

  61. [69]

    Kapteyn , J. C. 1922, , 55, 302, 10.1086/142670

  62. [70]

    2014, , 210, 14, 10.1088/0067-0049/210/1/14

    Kim , J.-h., Abel , T., Agertz , O., et al. 2014, , 210, 14, 10.1088/0067-0049/210/1/14

  63. [71]

    M., & Laporte , C

    Koop , O., Antoja , T., Helmi , A., Callingham , T. M., & Laporte , C. F. P. 2024, , 692, A50, 10.1051/0004-6361/202450911

  64. [72]

    2001, , 322, 231, 10.1046/j.1365-8711.2001.04022.x

    Kroupa , P. 2001, , 322, 231, 10.1046/j.1365-8711.2001.04022.x

  65. [74]

    1989 b , , 239, 571, 10.1093/mnras/239.2.571

    ---. 1989 b , , 239, 571, 10.1093/mnras/239.2.571

  66. [75]

    1991, , 367, L9, 10.1086/185920

    ---. 1991, , 367, L9, 10.1086/185920

  67. [76]

    Lacey , C. G. 1984, , 208, 687, 10.1093/mnras/208.4.687

  68. [77]

    Laporte , C. F. P., Johnston , K. V., G \'o mez , F. A., Garavito-Camargo , N., & Besla , G. 2018, , 481, 286, 10.1093/mnras/sty1574

  69. [78]

    D., et al

    Leitherer , C., Schaerer , D., Goldader , J. D., et al. 1999, , 123, 3, 10.1086/313233

  70. [79]

    R., Ivezi \'c , Z ., Quinn , T

    Loebman , S. R., Ivezi \'c , Z ., Quinn , T. R., et al. 2012, , 758, L23, 10.1088/2041-8205/758/1/L23

  71. [80]

    2014, , 794, 151, 10.1088/0004-637X/794/2/151

    ---. 2014, , 794, 151, 10.1088/0004-637X/794/2/151

  72. [81]

    2006, , 370, 773, 10.1111/j.1365-2966.2006.10501.x

    Mannucci , F., Della Valle , M., & Panagia , N. 2006, , 370, 773, 10.1111/j.1365-2966.2006.10501.x

  73. [82]

    R., et al

    McCluskey , F., Wetzel , A., Loebman , S. R., et al. 2024, , 527, 6926, 10.1093/mnras/stad3547

  74. [83]

    F., Parravano , A., & Hollenbach , D

    McKee , C. F., Parravano , A., & Hollenbach , D. J. 2015, , 814, 13, 10.1088/0004-637X/814/1/13

  75. [84]

    2019, , 883, 27, 10.3847/1538-4357/ab3afc

    Necib , L., Lisanti , M., Garrison-Kimmel , S., et al. 2019, , 883, 27, 10.3847/1538-4357/ab3afc

  76. [85]

    Oort , J. H. 1932, , 6, 249

  77. [86]

    E., Fielding , D

    Orr , M. E., Fielding , D. B., Hayward , C. C., & Burkhart , B. 2022, , 932, 88, 10.3847/1538-4357/ac6c26

  78. [87]

    E., Burkhart , B., Wetzel , A., et al

    Orr , M. E., Burkhart , B., Wetzel , A., et al. 2023, , 521, 3708, 10.1093/mnras/stad676

  79. [88]

    2024, , 528, 693, 10.1093/mnras/stae034

    Ou , X., Eilers , A.-C., Necib , L., & Frebel , A. 2024, , 528, 693, 10.1093/mnras/stae034

  80. [89]

    2025, arXiv e-prints, arXiv:2503.05877

    Ou , X., Necib , L., Wetzel , A., et al. 2025, arXiv e-prints, arXiv:2503.05877. 2503.05877

  81. [90]

    E., Wetzel , A., et al

    Panithanpaisal , N., Sanderson , R. E., Wetzel , A., et al. 2021, , 920, 10, 10.3847/1538-4357/ac1109

  82. [91]

    R., et al

    Parul , H., Bailin , J., Loebman , S. R., et al. 2025, , 537, 1571, 10.1093/mnras/staf137

  83. [92]

    Perez, F., & Granger, B. E. 2007, Computing in Science & Engineering, 9, 21, 10.1109/MCSE.2007.53

  84. [93]

    2024, adrn/TorusImaging: v0.1, v0.1, Zenodo, 10.5281/zenodo.10498412

    Price-Whelan, A. 2024, adrn/TorusImaging: v0.1, v0.1, Zenodo, 10.5281/zenodo.10498412

  85. [94]

    M., Hunt , J

    Price-Whelan , A. M., Hunt , J. A. S., Horta , D., et al. 2025, , 979, 115, 10.3847/1538-4357/ad969a

  86. [95]

    M., Hogg , D

    Price-Whelan , A. M., Hogg , D. W., Johnston , K. V., et al. 2021, , 910, 17, 10.3847/1538-4357/abe1b7

  87. [96]

    W., Bullock , J

    Purcell , C. W., Bullock , J. S., Tollerud , E. J., Rocha , M., & Chakrabarti , S. 2011, , 477, 301, 10.1038/nature10417

  88. [97]

    Read , J. I. 2014, Journal of Physics G Nuclear Physics, 41, 063101, 10.1088/0954-3899/41/6/063101

  89. [98]

    2024, , 972, 70, 10.3847/1538-4357/ad58d7

    Roche , C., Necib , L., Lin , T., Ou , X., & Nguyen , T. 2024, , 972, 70, 10.3847/1538-4357/ad58d7

  90. [99]

    C., Torrey , P., Villaescusa-Navarro , F., et al

    Rose , J. C., Torrey , P., Villaescusa-Navarro , F., et al. 2025, , 982, 68, 10.3847/1538-4357/adb8e5

  91. [100]

    C., & Ford , W

    Rubin , V. C., & Ford , W. Kent, J. 1970, , 159, 379, 10.1086/150317

  92. [101]

    E., Wetzel , A., Loebman , S., et al

    Sanderson , R. E., Wetzel , A., Loebman , S., et al. 2020, , 246, 6, 10.3847/1538-4365/ab5b9d

  93. [102]

    A., Bower , R

    Schaye , J., Crain , R. A., Bower , R. G., et al. 2015, , 446, 521, 10.1093/mnras/stu2058

  94. [103]

    1993, , 409, 563, 10.1086/172687

    Schwarzschild , M. 1993, , 409, 563, 10.1086/172687

  95. [104]

    1951, , 114, 385, 10.1086/145478

    Spitzer , Jr., L., & Schwarzschild , M. 1951, , 114, 385, 10.1086/145478

  96. [105]

    van der Marel , R. P. 1991, , 248, 515, 10.1093/mnras/248.3.515

  97. [106]

    2020, , 497, 4162, 10.1093/mnras/staa2114

    Vasiliev , E., & Belokurov , V. 2020, , 497, 4162, 10.1093/mnras/staa2114

  98. [107]

    2021, , 501, 2279, 10.1093/mnras/staa3673

    Vasiliev , E., Belokurov , V., & Erkal , D. 2021, , 501, 2279, 10.1093/mnras/staa3673

  99. [108]

    E., et al

    Virtanen, P., Gommers, R., Oliphant, T. E., et al. 2020, Nature Methods, 17, 261, 10.1038/s41592-019-0686-2

  100. [109]

    2014, , 444, 1518, 10.1093/mnras/stu1536

    Vogelsberger , M., Genel , S., Springel , V., et al. 2014, , 444, 1518, 10.1093/mnras/stu1536

  101. [110]

    L., Evans, N

    Watkins, L. L., Evans, N. W., & An, J. H. 2010, Mon. Not. R. Astron. Soc, 406, 264, 10.1111/j.1365-2966.2010.16708.x

  102. [111]

    2020 a , HaloAnalysis: Read and analyze halo catalogs and merger trees

    Wetzel , A., & Garrison-Kimmel , S. 2020 a , HaloAnalysis: Read and analyze halo catalogs and merger trees . 2002.014

  103. [112]

    2020 b , GizmoAnalysis: Read and analyze Gizmo simulations

    ---. 2020 b , GizmoAnalysis: Read and analyze Gizmo simulations . 2002.015

  104. [113]

    C., Sanderson , R

    Wetzel , A., Hayward , C. C., Sanderson , R. E., et al. 2023, , 265, 44, 10.3847/1538-4365/acb99a

  105. [114]

    R., Hopkins , P

    Wetzel , A. R., Hopkins , P. F., Kim , J.-h., et al. 2016, , 827, L23, 10.3847/2041-8205/827/2/L23

  106. [115]

    M., Barber , J., Chequers , M

    Widrow , L. M., Barber , J., Chequers , M. H., & Cheng , E. 2014, , 440, 1971, 10.1093/mnras/stu396

  107. [116]

    2022, , 2022, 031, 10.1088/1475-7516/2022/07/031

    Zentner , A., Dandavate , S., Slone , O., & Lisanti , M. 2022, , 2022, 031, 10.1088/1475-7516/2022/07/031

  108. [117]

    2013, , 772, 108, 10.1088/0004-637X/772/2/108

    Zhang , L., Rix , H.-W., van de Ven , G., et al. 2013, , 772, 108, 10.1088/0004-637X/772/2/108

Pith tools

Reviewed August 15, 2026 · model on record in the stance chip above.