pith. sign in

arxiv: 2605.18731 · v1 · pith:72V3BKITnew · submitted 2026-05-18 · 🌌 astro-ph.HE · astro-ph.SR

Pulse profile modelling of the 2024 outburst of the accreting millisecond pulsar SRGA J144459.2-604207

Bas Dorsman , Tuomo Salmi , Anna L. Watts , Mason Ng , Anna Bobrikova , Alessandro Di Marco , Duncan K. Galloway , Sebastien Guillot
show 9 more authors
Mariska Hoogkamer Yves Kini Fabio La Monaca Vladislav Loktev Matteo Lucchini Christian Malacaria Ying-Han Mao Alessandro Papitto Juri Poutanen
This is my paper

Pith reviewed 2026-05-20 08:52 UTC · model grok-4.3

classification 🌌 astro-ph.HE astro-ph.SR
keywords accreting millisecond pulsarpulse profile modelingneutron star mass and radiusX-ray polarizationNICERIXPEhotspot geometryrelativistic ray-tracing
0
0 comments X

The pith

NICER and IXPE data favor large mass and radius for the accreting pulsar SRGA J144459.2-604207 with two hotspots.

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

The paper applies relativistic ray-tracing to model the pulse profiles from combined NICER and IXPE observations of the 448-Hz accreting millisecond pulsar during its 2024 outburst. It seeks to constrain the neutron star mass, radius, and the locations and properties of its X-ray emitting regions. A sympathetic reader would care because these measurements bear on the equation of state of matter at the highest densities. The joint fit prefers a model with one large primary hotspot near the north rotational pole and a hotter secondary hotspot in the southern hemisphere, viewed at an inclination of 50 to 75 degrees. The primary region supplies most of the steady emission while the secondary dominates the pulsed signal, yet many fitted values sit near the edges of the allowed ranges.

Core claim

NICER and IXPE jointly favour a large mass and radius for our best-fitting model, for which the neutron star has two independent hotspots. The primary hotspot is centered near the northern rotational pole, the secondary in the southern hemisphere, and the observer inclination is in the range 50-75 degrees. The primary hotspot is large (up to half the surface area) and contributes the majority of the non-pulsed X-rays, while the secondary is hotter and the major contributor to the overall pulse profile shape.

What carries the argument

Two-hotspot relativistic ray-tracing model fitted simultaneously to NICER timing and IXPE polarization data.

If this is right

  • The neutron star is inferred to have both large mass and large radius.
  • The primary hotspot covers up to half the stellar surface and supplies most of the steady X-ray flux.
  • The secondary hotspot is hotter and largely determines the shape of the pulse profile.
  • The line of sight lies at an inclination between 50 and 75 degrees.
  • The numerical results depend on the precise method chosen to combine the two data sets.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The noted sensitivity to analysis method indicates that synthetic-data tests will be needed to validate joint fitting procedures for future multi-instrument campaigns.
  • If the near-bound parameters persist in higher-quality data, the model will need to incorporate atmospheric or column physics to remain viable.
  • The same two-hotspot framework can be applied to other accreting millisecond pulsars to enlarge the sample of mass-radius constraints.

Load-bearing premise

The two-hotspot relativistic ray-tracing model fully accounts for the emission physics without needing additional effects such as complex spot shapes, atmospheric scattering, or accretion-column contributions.

What would settle it

An independent mass or radius measurement for this neutron star that lies well below the large values preferred by the current two-hotspot fit.

Figures

Figures reproduced from arXiv: 2605.18731 by Alessandro Di Marco, Alessandro Papitto, Anna Bobrikova, Anna L. Watts, Bas Dorsman, Christian Malacaria, Duncan K. Galloway, Fabio La Monaca, Juri Poutanen, Mariska Hoogkamer, Mason Ng, Matteo Lucchini, Sebastien Guillot, Tuomo Salmi, Vladislav Loktev, Ying-Han Mao, Yves Kini.

Figure 1
Figure 1. Figure 1: The outburst as captured by MAXI, IXPE, and NICER. Only the NICER data selected for the analysis are shown. 3 DATA PREPARATION This section describes the preparation of the NICER and IXPE data into pulse profiles [PITH_FULL_IMAGE:figures/full_fig_p006_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Pulse profiles of NICER (left) and the three IXPE detector units (right). Top panels: bolometric counts. Bottom panels: phase-energy resolved pulse profiles. For IXPE, only the phase-energy resolved pulse profile of DU1 is shown, because the other two are very similar. and manually excised five time intervals (a total of 349 s) that con￾tained type-I X-ray bursts (for more on the bursts, see Molkov et al. … view at source ↗
Figure 3
Figure 3. Figure 3: Projection plots, spectra, pulse profiles and residuals for the (from left to right) NICER-only, IXPE-informed NICER, IXPE-only, NICER-informed IXPE analyses. The top row of panels show the projection plots of the maximum a posteriori (MAP) samples from the perspective of the observer. The red solid lines indicate the primary hotspots, the blue dash-dotted lines indicate the secondary hotspots, and the gre… view at source ↗
Figure 4
Figure 4. Figure 4: shows a corner plot of the inferred posteriors of 𝜃c. Interestingly, the combined run results in a lower 𝑀 = 1.928+0.012 −0.012 M⊙ and higher 𝑅eq= 13.94+0.04 −0.05 km than either of the individual runs. At first glance this result seems counter-intuitive, but we interpret it by looking at the 𝑀−𝑅eq posteriors. Here, we see that the NICER￾only posterior lies in the top-right corner, whereas the IXPE-only po… view at source ↗
Figure 5
Figure 5. Figure 5: Posterior distributions for the IXPE Stokes 𝐼, 𝑄, and 𝑈 anal￾ysis informed by NICER posteriors (IQU_prNICER), and two NICER analyses informed by IXPE posteriors. The first retains the flat 𝑁H prior (NICER_prIQU_flat_nH) and the second utilises the IXPE posterior of 𝑁H as prior (NICER_prIQU). These correspond to combination method 2 (See Section 4.4). See the caption of [PITH_FULL_IMAGE:figures/full_fig_p0… view at source ↗
read the original abstract

Pulse profile modelling via relativistic ray-tracing can constrain the system parameters of neutron stars, notably their mass and radius. Among these objects, accreting millisecond pulsars (AMPs) are promising targets, because they are bright in X-rays and their potentially polarized radiation can lead to complementary constraints on the emission geometry. We perform combined analysis of NICER and IXPE observations of the recently discovered the 448-Hz pulsar SRGA J144459.2-604207, with IXPE providing X-ray polarization information. NICER and IXPE jointly favour a large mass and radius for our best-fitting model, for which the neutron star has two independent hotspots. The primary hotspot is centered near the northern rotational pole, the secondary in the southern hemisphere, and the observer inclination is in the range 50-75 degrees. The primary hotspot is large (up to half the surface area) and contributes the majority of the non-pulsed X-rays, while the secondary is hotter and the major contributor to the overall pulse profile shape. However, many parameters are inferred to be near the prior bounds, which could indicate that the model does not adequately account for important physics. Furthermore, we tested several different methodologies for joint analysis of the two data sets: the results are sensitive to the method used, something that merits further study with synthetic data. In the future, we expect simultaneously recorded data will lead to improved parameter constraints, especially when multi-band and polarized data are combined.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript presents a combined NICER and IXPE analysis of the 448-Hz accreting millisecond pulsar SRGA J144459.2-604207 during its 2024 outburst. Using relativistic ray-tracing pulse-profile modeling with a two-hotspot geometry, the authors report that the data jointly favor a large neutron-star mass and radius. The primary hotspot is large (up to half the surface), centered near the northern rotational pole, and dominates the non-pulsed flux; the secondary hotspot is hotter, located in the southern hemisphere, and primarily shapes the pulse profile. Observer inclination is constrained to 50–75°. The paper notes that multiple parameters lie near prior boundaries and that the inferred values are sensitive to the choice of joint-analysis methodology, recommending synthetic-data tests for validation.

Significance. If the two-hotspot model proves adequate, the work would supply useful mass-radius constraints for an accreting millisecond pulsar by combining timing and polarimetric information. The joint use of NICER count-rate and IXPE polarization data is a methodological strength that could tighten geometric inferences. However, the reported proximity of parameters to prior bounds and the dependence on joint-analysis choices indicate that the specific large-mass/large-radius preference may not yet be robust, limiting its immediate utility for equation-of-state studies until the suggested validation is performed.

major comments (2)
  1. [Abstract and Results] The central claim that NICER and IXPE jointly favour a large mass and radius rests on the two-hotspot relativistic ray-tracing model. The abstract and results section explicitly state that many parameters lie near prior bounds; this raises the possibility that the model is forcing unphysical configurations (e.g., hotspot size reaching half the surface or extreme temperatures) to accommodate the data, which can systematically shift the mass-radius posteriors. Because the pulse shape and polarization signals depend directly on spot geometry, beaming, and temperature, boundary-hitting parameters constitute a load-bearing concern for the quantitative M-R result.
  2. [Discussion] The paper reports that the inferred mass and radius change with the choice of joint-analysis methodology for combining the NICER and IXPE datasets. Since the headline claim of large mass and radius is obtained from this joint fit, the lack of robustness to reasonable variations in analysis approach directly undermines in the reported values. The authors themselves flag the need for synthetic-data tests; until such tests are completed and the methodology dependence is quantified, the specific numerical constraints cannot be regarded as secure.
minor comments (2)
  1. Tabulate the exact prior ranges and any boundary conditions applied to each free parameter (mass, radius, hotspot colatitudes, sizes, temperatures, etc.) so that readers can immediately see which quantities are hitting the edges.
  2. Clarify in the figure captions or text whether the reported 50–75° inclination range is the 68 % or 90 % credible interval, and whether it is marginalized over the full posterior or conditioned on the best-fit hotspot geometry.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful and constructive review of our manuscript. We address each major comment below and have made targeted revisions to improve clarity and emphasize limitations.

read point-by-point responses

  1. Referee: [Abstract and Results] The central claim that NICER and IXPE jointly favour a large mass and radius rests on the two-hotspot relativistic ray-tracing model. The abstract and results section explicitly state that many parameters lie near prior bounds; this raises the possibility that the model is forcing unphysical configurations (e.g., hotspot size reaching half the surface or extreme temperatures) to accommodate the data, which can systematically shift the mass-radius posteriors. Because the pulse shape and polarization signals depend directly on spot geometry, beaming, and temperature, boundary-hitting parameters constitute a load-bearing concern for the quantitative M-R result.

    Authors: We agree this is a substantive concern. The manuscript already states that many parameters lie near prior bounds and that this could indicate missing physics. In the revised version we have expanded the discussion to quantify the effect of boundary proximity on the M-R posteriors (via additional prior-variation runs) and have added explicit language in both the abstract and results cautioning that the precise numerical values should be interpreted with care for EOS applications. The two-hotspot geometry remains the statistically preferred model, but we now more clearly separate the qualitative geometric conclusions from the quantitative M-R constraints. revision: partial

  2. Referee: [Discussion] The paper reports that the inferred mass and radius change with the choice of joint-analysis methodology for combining the NICER and IXPE datasets. Since the headline claim of large mass and radius is obtained from this joint fit, the lack of robustness to reasonable variations in analysis approach directly undermines in the reported values. The authors themselves flag the need for synthetic-data tests; until such tests are completed and the methodology dependence is quantified, the specific numerical constraints cannot be regarded as secure.

    Authors: We concur that the observed sensitivity to joint-analysis choices limits the robustness of the specific M-R numbers. The original text already reports results from multiple methodologies and notes the need for synthetic-data validation. In revision we have added a quantitative comparison table of M-R posteriors across the tested methods and have strengthened the discussion of this dependence. Full synthetic-data tests are computationally demanding and were not completed for the current submission; we have therefore inserted a clearer statement that the reported numerical constraints should be regarded as preliminary pending such validation, while the geometric inferences (two hotspots, inclination range) are more stable across methods. revision: partial

Circularity Check

0 steps flagged

No significant circularity; derivation is data-driven fit to external observations

full rationale

The paper conducts Bayesian inference of neutron-star mass, radius, and hotspot geometry by fitting a two-hotspot relativistic ray-tracing model directly to independent NICER count-rate and IXPE polarization data. No equation reduces the reported mass or radius to a fitted normalization constant, nor does any step equate a prediction to its own input by construction. The authors explicitly flag that several parameters lie near prior bounds and that results are sensitive to joint-analysis methodology, but these are acknowledged model limitations rather than self-referential derivations. The central claim therefore rests on external observational constraints and remains self-contained.

Axiom & Free-Parameter Ledger

5 free parameters · 2 axioms · 0 invented entities

The model relies on standard general-relativistic ray-tracing for a rotating neutron star plus several free parameters describing hot-spot geometry, temperature, and observer angle that are fitted to the data.

free parameters (5)
  • neutron-star mass
    Fitted parameter whose posterior is reported as large; central to the headline claim.
  • neutron-star radius
    Fitted parameter whose posterior is reported as large; central to the headline claim.
  • primary hotspot size and location
    Fitted geometric parameters; primary spot described as large and near north pole.
  • secondary hotspot temperature and location
    Fitted parameters; secondary spot hotter and in southern hemisphere.
  • observer inclination
    Fitted angle reported in 50-75 degree range.
axioms (2)
  • domain assumption Relativistic ray-tracing accurately maps emission from surface hotspots to the observer for the chosen spacetime metric.
    Invoked throughout the pulse-profile modeling section.
  • domain assumption Two independent circular hotspots are sufficient to describe the emission geometry.
    Adopted as the best-fitting model; paper notes parameters near bounds may indicate inadequacy.

pith-pipeline@v0.9.0 · 5879 in / 1717 out tokens · 33208 ms · 2026-05-20T08:52:29.469294+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

What do these tags mean?
matches
The paper's claim is directly supported by a theorem in the formal canon.
supports
The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses
The paper appears to rely on the theorem as machinery.
contradicts
The paper's claim conflicts with a theorem or certificate in the canon.
unclear
Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

246 extracted references · 246 canonical work pages · 84 internal anchors

  1. [1]

    2021, AJ, 162, 208, doi: 10.3847/1538-3881/ac19b0

    The Instrument of the Imaging X-Ray Polarimetry Explorer. , keywords =. doi:10.3847/1538-3881/ac19b0 , archivePrefix =. 2108.00284 , primaryClass =

    work page doi:10.3847/1538-3881/ac19b0

  2. [2]

    , keywords =

    The Neutron Star Mass, Distance, and Inclination from Precision Timing of the Brilliant Millisecond Pulsar J0437-4715. , keywords =. doi:10.3847/2041-8213/ad614a , archivePrefix =. 2407.07132 , primaryClass =

    work page doi:10.3847/2041-8213/ad614a 2041

  3. [3]

    The MAXI Mission on the ISS: Science and Instruments for Monitoring All Sky X-Ray Images

    The MAXI Mission on the ISS: Science and Instruments for Monitoring All-Sky X-Ray Images. , keywords =. doi:10.1093/pasj/61.5.999 , archivePrefix =. 0906.0631 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/pasj/61.5.999

  4. [4]

    2021 , pages =

    SRG X-ray orbital observatory. Its telescopes and first scientific results. , keywords =. doi:10.1051/0004-6361/202141179 , archivePrefix =. 2104.13267 , primaryClass =

    work page doi:10.1051/0004-6361/202141179

  5. [5]

    The disc instability model of dwarf-novae and low-mass X-ray binary transients

    The disc instability model of dwarf novae and low-mass X-ray binary transients. , keywords =. doi:10.1016/S1387-6473(01)00112-9 , archivePrefix =. astro-ph/0102072 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1016/s1387-6473(01)00112-9

  6. [6]

    Pulsar Polar Cap Heating and Surface Thermal X-Ray Emission. I. Curvature Radiation Pair Fronts. , keywords =. doi:10.1086/321589 , archivePrefix =. astro-ph/0104146 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/321589

  7. [7]

    Analyzing the Data from X-ray Polarimeters with Stokes Parameters

    Analyzing the data from X-ray polarimeters with Stokes parameters. Astroparticle Physics , keywords =. doi:10.1016/j.astropartphys.2015.02.007 , archivePrefix =. 1409.6214 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1016/j.astropartphys.2015.02.007 2015

  8. [8]

    , keywords =

    Handling Background in IXPE polarimetric data. , keywords =. doi:10.3847/1538-3881/acba0f , archivePrefix =. 2302.02927 , primaryClass =

    work page doi:10.3847/1538-3881/acba0f

  9. [9]

    , keywords =

    A Weighted Analysis to Improve the X-Ray Polarization Sensitivity of the Imaging X-ray Polarimetry Explorer. , keywords =. doi:10.3847/1538-3881/ac51c9 , archivePrefix =. 2202.01093 , primaryClass =

    work page doi:10.3847/1538-3881/ac51c9

  10. [10]

    , keywords =

    The Radius of PSR J0437─4715 from NICER Data. , keywords =. doi:10.3847/2041-8213/ae5057 , archivePrefix =. 2512.08790 , primaryClass =

    work page doi:10.3847/2041-8213/ae5057 2041

  11. [11]

    , keywords =

    Discovery of SRGA J144459.2‑604207 with the SRG/ART-XC telescope: A well-tempered bursting accreting millisecond X-ray pulsar. , keywords =. doi:10.1051/0004-6361/202450581 , archivePrefix =. 2404.19709 , primaryClass =

    work page doi:10.1051/0004-6361/202450581

  12. [12]

    , keywords =

    A Comprehensive Study of Type I (Thermonuclear) Bursts in the New Transient SRGA J144459.2 604207. , keywords =. doi:10.3847/1538-4357/adadee , archivePrefix =. 2412.05779 , primaryClass =

    work page doi:10.3847/1538-4357/adadee

  13. [13]

    , keywords =

    Disk reflection and energetics from the accreting millisecond pulsar SRGA J144459.2‑604207. , keywords =. doi:10.1051/0004-6361/202554075 , archivePrefix =. 2502.08239 , primaryClass =

    work page doi:10.1051/0004-6361/202554075

  14. [14]

    , keywords =

    Relativistic X-ray reflection and thermonuclear burst from accreting millisecond X-ray pulsar SRGA J144459.2 604207. , keywords =. doi:10.1093/mnras/staf1207 , archivePrefix =. 2507.15982 , primaryClass =

    work page doi:10.1093/mnras/staf1207

  15. [15]

    , keywords =

    Timing and Spectral Studies of SRGA J144459.2‑604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT, and INTEGRAL During its 2024 Outburst. , keywords =. doi:10.3847/1538-4357/adf0ff , archivePrefix =. 2507.00793 , primaryClass =

    work page doi:10.3847/1538-4357/adf0ff 2024

  16. [16]

    The Two-Phase Pair Corona Model for Active Galactic Nuclei and X-ray Binaries: How to Obtain Exact Solutions

    The Two-Phase Pair Corona Model for Active Galactic Nuclei and X-Ray Binaries: How to Obtain Exact Solutions. , keywords =. doi:10.1086/177865 , archivePrefix =. astro-ph/9605073 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/177865

  17. [17]

    Neutron star mass and radius measurements from atmospheric model fits to X-ray burst cooling tail spectra

    Neutron star mass and radius measurements from atmospheric model fits to X-ray burst cooling tail spectra. , keywords =. doi:10.1051/0004-6361/201731082 , archivePrefix =. 1709.09120 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201731082

  18. [18]

    Equation of state constraints for the cold dense matter inside neutron stars using the cooling tail method

    Equation of state constraints for the cold dense matter inside neutron stars using the cooling tail method. , keywords =. doi:10.1051/0004-6361/201527416 , archivePrefix =. 1509.06561 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201527416

  19. [19]

    Neutron star stiff equation of state derived from cooling phases of the X-ray burster 4U 1724-307

    A Neutron Star Stiff Equation of State Derived from Cooling Phases of the X-Ray Burster 4U 1724-307. , keywords =. doi:10.1088/0004-637X/742/2/122 , archivePrefix =. 1004.4871 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/742/2/122

  20. [20]

    , keywords =

    The Radius of the High-mass Pulsar PSR J0740+6620 with 3.6 yr of NICER Data. , keywords =. doi:10.3847/1538-4357/ad5f1f , archivePrefix =. 2406.14466 , primaryClass =

    work page doi:10.3847/1538-4357/ad5f1f

  21. [21]

    , keywords =

    Polarized radiation from an accretion shock in accreting millisecond pulsars using exact Compton scattering formalism. , keywords =. doi:10.1051/0004-6361/202346833 , archivePrefix =. 2309.02329 , primaryClass =

    work page doi:10.1051/0004-6361/202346833

  22. [22]

    , keywords =

    Energy spectra of low-mass binary X-ray sources observed from Tenma. , keywords =

    work page

  23. [23]

    Dense matter with eXTP

    Dense matter with eXTP. Science China Physics, Mechanics, and Astronomy , keywords =. doi:10.1007/s11433-017-9188-4 , archivePrefix =. 1812.04021 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1007/s11433-017-9188-4

  24. [24]

    Xiamen-CUSTIPEN Workshop on the Equation of State of Dense Neutron-Rich Matter in the Era of Gravitational Wave Astronomy , year = 2019, series =

    Constraining the neutron star equation of state using pulse profile modeling. Xiamen-CUSTIPEN Workshop on the Equation of State of Dense Neutron-Rich Matter in the Era of Gravitational Wave Astronomy , year = 2019, series =. doi:10.1063/1.5117798 , archivePrefix =. 1904.07012 , primaryClass =

    work page doi:10.1063/1.5117798 2019

  25. [25]

    PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter

    PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter. , keywords =. doi:10.3847/2041-8213/ab50c5 , archivePrefix =. 1912.05705 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/2041-8213/ab50c5 2041

  26. [26]

    , keywords =

    A NICER View of PSR J0030+0451: Millisecond Pulsar Parameter Estimation. , keywords =. doi:10.3847/2041-8213/ab481c , archivePrefix =. 1912.05702 , primaryClass =

    work page doi:10.3847/2041-8213/ab481c 2041

  27. [27]

    Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. I. The Millisecond Pulsar X-Ray Data Set. , keywords =. doi:10.3847/2041-8213/ab53eb , archivePrefix =. 1912.05706 , primaryClass =

    work page doi:10.3847/2041-8213/ab53eb 2041

  28. [28]

    Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. II. Emission from Hot Spots on a Rapidly Rotating Neutron Star. , keywords =. doi:10.3847/2041-8213/ab5968 , archivePrefix =. 1912.05707 , primaryClass =

    work page doi:10.3847/2041-8213/ab5968 2041

  29. [29]

    The effect of neglecting variability

    Pulse profile modelling of thermonuclear burst oscillations - I. The effect of neglecting variability. , keywords =. doi:10.1093/mnras/stad1030 , archivePrefix =. 2304.01770 , primaryClass =

    work page doi:10.1093/mnras/stad1030

  30. [30]

    Determining Neutron Star Properties by Fitting Oblate-Star Waveforms To X-ray Burst Oscillations

    Determining Neutron Star Properties by Fitting Oblate-star Waveform Models to X-Ray Burst Oscillations. , keywords =. doi:10.1088/0004-637X/808/1/31 , archivePrefix =. 1407.2579 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/808/1/31

  31. [31]

    , keywords =

    Hot spots on neutron stars - The near-field gravitational lens. , keywords =. doi:10.1086/161498 , adsurl =

    work page doi:10.1086/161498

  32. [32]

    , year = 1998, month = jul, volume =

    A millisecond pulsar in an X-ray binary system. , year = 1998, month = jul, volume =. doi:10.1038/28557 , adsurl =

    work page doi:10.1038/28557 1998

  33. [33]

    Springer International Publishing, Cham, pp 87--124, @doi 10.1007/978-3-030-85198-9_4 , https://doi.org/10.1007/978-3-030-85198-9_4

    Accretion Powered X-ray Millisecond Pulsars. Millisecond Pulsars , year = 2022, editor =. doi:10.1007/978-3-030-85198-9_4 , adsurl =

    work page doi:10.1007/978-3-030-85198-9_4 2022

  34. [34]

    Discovery of the X-ray transient SAX J1808.4-3658, a likely low mass X-ray binary

    Discovery of the X-ray transient SAX J1808.4-3658, a likely low-mass X-ray binary. , keywords =. doi:10.48550/arXiv.astro-ph/9802098 , archivePrefix =. astro-ph/9802098 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.astro-ph/9802098

  35. [35]

    , keywords =

    Timing Analysis of the 2022 Outburst of the Accreting Millisecond X-Ray Pulsar SAX J1808.4-3658: Hints of an Orbital Shrinking. , keywords =. doi:10.3847/2041-8213/acad81 , archivePrefix =. 2212.09778 , primaryClass =

    work page doi:10.3847/2041-8213/acad81 2022

  36. [36]

    Helium-rich thermonuclear bursts and the distance to the accretion-powered millisecond pulsar SAX J1808.4-3658

    Helium-rich Thermonuclear Bursts and the Distance to the Accretion-powered Millisecond Pulsar SAX J1808.4-3658. , keywords =. doi:10.1086/507598 , archivePrefix =. astro-ph/0607213 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/507598

  37. [37]

    The Journal of Open Source Software , keywords =

    X-PSI: A Python package for neutron star X-ray pulse simulation and inference. The Journal of Open Source Software , keywords =. doi:10.21105/joss.04977 , adsurl =

    work page doi:10.21105/joss.04977

  38. [38]

    Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. III. Model Description and Verification of Parameter Estimation Codes. , keywords =. doi:10.3847/2041-8213/abfb79 , archivePrefix =. 2104.06928 , primaryClass =

    work page doi:10.3847/2041-8213/abfb79 2041

  39. [39]

    , keywords =

    Simultaneous X-Ray and Optical Observations of GX 339-4 in an X-Ray High State. , keywords =. doi:10.1086/164534 , adsurl =

    work page doi:10.1086/164534

  40. [40]

    , keywords =

    Accretion discs in astrophysics. , keywords =. doi:10.1146/annurev.aa.19.090181.001033 , adsurl =

    work page doi:10.1146/annurev.aa.19.090181.001033

  41. [41]

    , keywords =

    Constraining the magnetic field geometry of the millisecond pulsar PSR J0030+0451 from joint radio, thermal X-ray, and -ray emission. , keywords =. doi:10.1051/0004-6361/202346913 , archivePrefix =. 2309.03620 , primaryClass =

    work page doi:10.1051/0004-6361/202346913

  42. [42]

    , keywords =

    The Multipolar Magnetic Field of the Millisecond Pulsar PSR J0030+0451. , keywords =. doi:10.3847/1538-4357/abcec0 , archivePrefix =. 2009.08567 , primaryClass =

    work page doi:10.3847/1538-4357/abcec0 2009

  43. [43]

    , keywords =

    A NICER Thermonuclear Burst from the Millisecond X-Ray Pulsar SAX J1808.4-3658. , keywords =. doi:10.3847/2041-8213/ab4ae1 , archivePrefix =. 1909.03595 , primaryClass =

    work page doi:10.3847/2041-8213/ab4ae1 2041

  44. [44]

    , keywords =

    Timing the Pulsations of the Accreting Millisecond Pulsar SAX J1808.4-3658 during Its 2019 Outburst. , keywords =. doi:10.3847/1538-4357/ab9827 , archivePrefix =. 1910.03062 , primaryClass =

    work page doi:10.3847/1538-4357/ab9827 2019

  45. [45]

    , keywords =

    AstroSat observation of the accreting millisecond X-ray pulsar SAX J1808.4-3658 during its 2019 outburst. , keywords =. doi:10.1093/mnras/stac3779 , archivePrefix =. 2212.10088 , primaryClass =

    work page doi:10.1093/mnras/stac3779 2019

  46. [46]

    NuSTAR and XMM-Newton broad-band spectrum of SAX J1808.4-3658 during its latest outburst in 2015

    NuSTAR and XMM-Newton broad-band spectrum of SAX J1808.4-3658 during its latest outburst in 2015. , keywords =. doi:10.1093/mnras/sty2974 , archivePrefix =. 1811.00940 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/sty2974 2015

  47. [47]

    , keywords =

    GRMHD simulations of accreting neutron stars with non-dipole fields. , keywords =. doi:10.1093/mnras/stac1817 , archivePrefix =. 2204.00249 , primaryClass =

    work page doi:10.1093/mnras/stac1817

  48. [48]

    The Reflares and Outburst Evolution in the Accreting Millisecond Pulsar SAX J1808.4-3658: a Disk Truncated Near Co-rotation?

    The Reflares and Outburst Evolution in the Accreting Millisecond Pulsar SAX J1808.4-3658: A Disk Truncated Near Co-Rotation?. , keywords =. doi:10.3847/0004-637X/817/2/100 , archivePrefix =. 1504.05048 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/0004-637x/817/2/100

  49. [49]

    M., Langer, N., & Kramer, M

    Varying disc-magnetosphere coupling as the origin of pulse profile variability in SAX J1808.4-3658. , keywords =. doi:10.1111/j.1365-2966.2011.19360.x , archivePrefix =. 1107.0180 , primaryClass =

    work page doi:10.1111/j.1365-2966.2011.19360.x 2011

  50. [50]

    Nature Astronomy , keywords =

    Optical and ultraviolet pulsed emission from an accreting millisecond pulsar. Nature Astronomy , keywords =. doi:10.1038/s41550-021-01308-0 , archivePrefix =. 2102.11704 , primaryClass =

    work page doi:10.1038/s41550-021-01308-0

  51. [51]

    Bayesian parameter constraints for neutron star masses and radii using X-ray timing observations of accretion-powered millisecond pulsars

    Bayesian parameter constraints for neutron star masses and radii using X-ray timing observations of accretion-powered millisecond pulsars. , keywords =. doi:10.1051/0004-6361/201833348 , archivePrefix =. 1805.01149 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201833348

  52. [52]

    , keywords =

    Neutron star parameter constraints for accretion-powered millisecond pulsars from the simulated IXPE data. , keywords =. doi:10.1051/0004-6361/202039470 , archivePrefix =. 2009.09744 , primaryClass =

    work page doi:10.1051/0004-6361/202039470 2009

  53. [53]

    , keywords =

    Effects of scattering in the accretion funnel on the pulse profiles of accreting millisecond pulsars. , keywords =. doi:10.1051/0004-6361/202348153 , archivePrefix =. 2312.08142 , primaryClass =

    work page doi:10.1051/0004-6361/202348153

  54. [54]

    L., 2021, in Belloni T

    Accreting Millisecond X-ray Pulsars. Timing Neutron Stars: Pulsations, Oscillations and Explosions , year = 2021, editor =. doi:10.1007/978-3-662-62110-3_4 , archivePrefix =. 1206.2727 , primaryClass =

    work page doi:10.1007/978-3-662-62110-3_4 2021

  55. [55]

    The two-hour orbit of a binary millisecond X-ray pulsar

    The two-hour orbit of a binary millisecond X-ray pulsar. , keywords =. doi:10.1038/28561 , archivePrefix =. astro-ph/9804248 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1038/28561

  56. [56]

    The Oblate Schwarzschild Approximation for Light Curves of Rapidly Rotating Neutron Stars

    The Oblate Schwarzschild Approximation for Light Curves of Rapidly Rotating Neutron Stars. , keywords =. doi:10.1086/518648 , archivePrefix =. astro-ph/0703123 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/518648

  57. [57]

    , keywords =

    Inferring system parameters from the bursts of the accretion-powered pulsar IGR J17498-2921. , keywords =. doi:10.1093/mnras/stae2422 , archivePrefix =. 2403.16471 , primaryClass =

    work page doi:10.1093/mnras/stae2422

  58. [58]

    Nested Sampling. Bayesian Inference and Maximum Entropy Methods in Science and Engineering: 24th International Workshop on Bayesian Inference and Maximum Entropy Methods in Science and Engineering , year = 2004, editor =. doi:10.1063/1.1835238 , adsurl =

    work page doi:10.1063/1.1835238 2004

  59. [59]

    PyMultiNest: Python interface for MultiNest

    work page

  60. [60]

    Analytical Hot Spot Shapes and Magnetospheric Radius from 3D Simulations of Magnetospheric Accretion

    Analytical hotspot shapes and magnetospheric radius from 3D simulations of magnetospheric accretion. , keywords =. doi:10.1093/mnras/stt945 , archivePrefix =. 1303.4681 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stt945

  61. [61]

    2001, MNRAS, 322, 231, doi:10.1046/j.1365-8711.2001

    Atmospheres and spectra of strongly magnetized neutron stars. , keywords =. doi:10.1046/j.1365-8711.2001.04801.x , archivePrefix =. astro-ph/0104199 , primaryClass =

    work page doi:10.1046/j.1365-8711.2001.04801.x 2001

  62. [62]

    A Neutron Star with a Carbon Atmosphere in the Cassiopeia A Supernova Remnant

    A neutron star with a carbon atmosphere in the Cassiopeia A supernova remnant. , keywords =. doi:10.1038/nature08525 , archivePrefix =. 0911.0672 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1038/nature08525

  63. [63]

    2003, MNRAS, 344, 1000, doi: 10.1046/j.1365-8711.2003.06897.x

    On the nature of the X-ray emission from the accreting millisecond pulsar SAX J1808.4-3658. , keywords =. doi:10.1046/j.1365-8711.2003.06773.x , archivePrefix =. astro-ph/0303084 , primaryClass =

    work page doi:10.1046/j.1365-8711.2003.06773.x 2003

  64. [64]

    Limits on Mass and Radius for the ms-Period X-ray Pulsar SAX J1808.4-3658

    Limits on Mass and Radius for the Millisecond-Period X-Ray Pulsar SAX J1808.4-3658. , keywords =. doi:10.1086/523794 , archivePrefix =. astro-ph/0703287 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/523794

  65. [65]

    40 Years of Pulsars: Millisecond Pulsars, Magnetars and More , year = 2008, editor =

    Time delays, Doppler effects and oblateness: results for the ms pulsar SAXJ1808-3658. 40 Years of Pulsars: Millisecond Pulsars, Magnetars and More , year = 2008, editor =. doi:10.1063/1.2900293 , adsurl =

    work page doi:10.1063/1.2900293 2008

  66. [66]

    A Simple Comptonization Model

    A Simple Comptonization Model. , keywords =. doi:10.1086/648535 , archivePrefix =. 0810.1758 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/648535

  67. [67]

    L., Kuncic, Z., & Wu, K

    Accreting millisecond pulsar SAX J1808.4-3658 during its 2002 outburst: evidence for a receding disc. , keywords =. doi:10.1111/j.1365-2966.2009.15477.x , archivePrefix =. 0901.0073 , primaryClass =

    work page doi:10.1111/j.1365-2966.2009.15477.x 2002

  68. [68]

    On the nature of pulse profile variations and timing noise in accreting millisecond pulsars

    On the Nature of Pulse Profile Variations and Timing Noise in Accreting Millisecond Pulsars. , keywords =. doi:10.1088/0004-637X/706/1/L129 , archivePrefix =. 0910.5868 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/706/1/l129

  69. [69]

    Light curves and polarization of accretion- and nuclear-powered millisecond pulsars

    Light curves and polarization of accretion- and nuclear-powered millisecond pulsars. , keywords =. doi:10.1051/0004-6361:20041084 , archivePrefix =. astro-ph/0408250 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361:20041084

  70. [70]

    , keywords =

    Comptonization of low-frequency radiation in accretion disks Angular distribution and polarization of hard radiation. , keywords =

    work page

  71. [71]

    Multi-epoch Analysis of Pulse Shapes from the Neutron Star SAX J1808.4-3658

    Multi-epoch Analysis of Pulse Shapes from the Neutron Star SAX J1808.4-3658. , keywords =. doi:10.1088/0004-637X/726/1/56 , archivePrefix =. 0911.0887 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/726/1/56

  72. [72]

    Constraints on the Properties of the Neutron Star XTE J1814-338 from Pulse Shape Models

    Constraints on the Properties of the Neutron Star XTE J1814-338 from Pulse-Shape Models. , keywords =. doi:10.1088/0004-637X/691/2/1235 , archivePrefix =. 0806.0824 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/691/2/1235

  73. [73]

    Universality of the Acceleration Due to Gravity on the Surface of a Rapidly Rotating Neutron Star

    Universality of the Acceleration due to Gravity on the Surface of a Rapidly Rotating Neutron Star. , keywords =. doi:10.1088/0004-637X/791/2/78 , archivePrefix =. 1404.0609 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/791/2/78

  74. [74]

    Bounds on the Compactness of Neutron Stars from Brightness Oscillations

    Bounds on the Compactness of Neutron Stars from Brightness Oscillations during X-Ray Bursts. , keywords =. doi:10.1086/311335 , archivePrefix =. astro-ph/9711325 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/311335

  75. [75]

    Three-dimensional Simulations of Disk Accretion to an Inclined Dipole. II. Hot Spots and Variability. , keywords =. doi:10.1086/421867 , archivePrefix =. astro-ph/0404496 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/421867

  76. [76]

    Modelling the behaviour of accretion flows in X-ray binaries

    Modelling the behaviour of accretion flows in X-ray binaries. Everything you always wanted to know about accretion but were afraid to ask. , keywords =. doi:10.1007/s00159-007-0006-1 , archivePrefix =. 0708.0148 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1007/s00159-007-0006-1

  77. [77]

    , keywords =

    A NICER View of the Nearest and Brightest Millisecond Pulsar: PSR J0437-4715. , keywords =. doi:10.3847/2041-8213/ad5a6f , archivePrefix =. 2407.06789 , primaryClass =

    work page doi:10.3847/2041-8213/ad5a6f 2041

  78. [78]

    , keywords =

    Exploring Waveform Variations among Neutron Star Ray-tracing Codes for Complex Emission Geometries. , keywords =. doi:10.3847/1538-4357/ad7255 , archivePrefix =. 2406.07285 , primaryClass =

    work page doi:10.3847/1538-4357/ad7255

  79. [79]

    Determining neutron star masses and radii using energy-resolved waveforms of X-ray burst oscillations

    Determining Neutron Star Masses and Radii Using Energy-resolved Waveforms of X-Ray Burst Oscillations. , keywords =. doi:10.1088/0004-637X/776/1/19 , archivePrefix =. 1304.2330 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/776/1/19

  80. [80]

    , keywords =

    The Radius of PSR J0740+6620 from NICER with NICER Background Estimates. , keywords =. doi:10.3847/1538-4357/ac983d , archivePrefix =. 2209.12840 , primaryClass =

    work page doi:10.3847/1538-4357/ac983d

Showing first 80 references.