pith. sign in

arxiv: 2606.11133 · v1 · pith:5VXAR6VUnew · submitted 2026-06-09 · 🌌 astro-ph.HE

Resolving SLX 1744-299 and SLX 1744-300 in the hard X-ray band: implications for their ultracompact nature

Enzo A. Saavedra , Montserrat Armas Padilla , Teo Mu\~noz-Darias This is my paper

Pith reviewed 2026-06-27 12:09 UTC · model grok-4.3

classification 🌌 astro-ph.HE
keywords ultracompact X-ray binarieslow-mass X-ray binariesNuSTARGalactic CentreX-ray burstsdisc instability modelhard statemass accretion rate
0
0 comments X

The pith

NuSTAR resolves two sources yielding accretion rates that favour ultracompact orbital periods

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

The paper reports a NuSTAR observation that spatially resolves SLX 1744-299 and SLX 1744-300 above 10 keV for the first time, finding both in the hard state with a flux ratio of about 1.15. SLX 1744-299 shows a gradual flux decline while SLX 1744-300 remains steady and produces two short-recurrence Type-I bursts. Using prior distance upper limits the work derives persistent luminosity upper bounds of L_X ≲ 1.1×10^36 erg s^{-1} and L_X ≲ 2.6×10^36 erg s^{-1} in the 3-78 keV band, then converts these to mass-accretion rates and compares them to the critical values of the disc instability model.

Core claim

The resulting accretion-rate upper limits compared with disc instability model thresholds favour P_orb ≲ 90 min for SLX 1744-299 and P_orb ≲ 105-155 min for SLX 1744-300, both formally compatible with the ultracompact regime although the case for SLX 1744-299 is stronger given its previously reported intermediate-duration burst.

What carries the argument

Comparison of observationally derived mass-accretion rates to the critical accretion-rate thresholds of the disc instability model to obtain orbital-period upper limits

If this is right

  • SLX 1744-299 is a strong candidate ultracompact X-ray binary with P_orb ≲ 90 min.
  • SLX 1744-300 is compatible with P_orb ≲ 105-155 min and therefore possibly ultracompact as well.
  • Both sources were observed in the hard state with thermal Comptonisation spectra and low root-mean-square variability.
  • SLX 1744-300's short-recurrence bursts indicate mixed H/He burning on the neutron-star surface.

Where Pith is reading between the lines

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

  • Tighter distance constraints would narrow or remove the allowed orbital-period windows.
  • These sources offer test cases for binary-evolution models in the dense Galactic Centre environment.
  • Future timing observations could search for direct orbital signatures to confirm or refute the short-period limits.

Load-bearing premise

The previously reported upper limits on distance are accurate enough to yield reliable luminosity upper bounds and the disc instability model critical rates apply directly to these systems.

What would settle it

A distance measurement for either source that is substantially smaller than the current upper limit, which would raise the luminosity and accretion-rate bounds above the critical values for the claimed short periods.

Figures

Figures reproduced from arXiv: 2606.11133 by Enzo A. Saavedra, Montserrat Armas Padilla, Teo Mu\~noz-Darias.

Figure 1
Figure 1. Figure 1: NuSTAR FPMA module image in the 3–78 keV energy band showing the field of the LMXBs SLX 1744-299 (north) and SLX 1744-300 (south). The pulsar PSR J1747-2958 (also known as “the Mouse”) is visible within the field. The dashed circular regions indicate the event and background extraction regions for each source. the telescope aboard Spacelab 2 (Skinner et al. 1987, see also Kawai et al. 1988), and only ident… view at source ↗
Figure 2
Figure 2. Figure 2: Left panel: background-corrected NuSTAR light curve of SLX 1744−299 with a time bin of 500 sec. From top to bot￾tom: the total light curve in the 3–78 keV energy range, the soft band (3–9 keV), the hard band (9–78 keV), and the hardness ratio (hard/soft) as a function of time. Right panel: unfolded NuSTAR FPMA (red) and FPMB (black) spectrum (top) and resid￾uals (middle and bottom) using the const×TBabs×(n… view at source ↗
Figure 3
Figure 3. Figure 3: Time-resolved spectral evolution of SLX 1744 [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Left panel: The top panel shows the background-corrected NuSTAR light curve of SLX 1744−300 with a time bin of 1 s, including two Type-I bursts superimposed on the persistent emission; the insets show each burst and the best-fit model from Eq. 1. Right panel: Unfolded NuSTAR FPMA (red) and FPMB (black) spectrum (top) and residuals (middle and bottom) using the const×TBabs×(nthComp) model. The bottom panel … view at source ↗
Figure 5
Figure 5. Figure 5: Stability limits for non-irradiated C/O discs, irradiated mixed-composition discs and irradiated solar-composition discs based on Menou et al. (2002) and Lasota et al. (2008). In both cases, the upper limits on the mass transfer rate reported in this work yield upper limits on Porb. time between the two bursts (∆t ≃ 1.82 × 104 s), we infer a bolometric persistent flux of ∼ (1.1 − 1.4) × 10−10 erg cm−2 s −1… view at source ↗
read the original abstract

Persistent, low-luminosity low-mass X-ray binaries (LMXBs) offer a unique opportunity to study accretion in this poorly understood regime, as well as to unveil new members of the ultracompact X-ray binary (UCXB) family, characterised by orbital periods ($P_{\rm orb}$) shorter than $\sim 80$ min. We report on a NuSTAR archival observation that, for the first time above 10 keV, spatially resolves the Galactic Centre pair SLX 1744$-$299 and SLX 1744$-$300. We find SLX 1744$-$300 to be slightly brighter, with a flux ratio of $\sim 1.15$, increasing to $\sim 1.3$ when extrapolated to 0.5$-$10 keV. Both the timing (root-mean-square variability) and spectral properties (well described in both cases by a thermal Comptonisation model) indicate that the systems were in the hard state. The two sources, however, display markedly different behaviour throughout the observation. SLX 1744$-$299 shows a gradual flux decline consistent with a decrease in the mass-accretion rate, whereas SLX 1744$-$300 remains steady but exhibits two short-recurrence Type-I X-ray bursts indicative of mixed H/He burning. Combining our results with previously reported upper limits on the distance, we derive low persistent X-ray luminosities of $L_{\rm X}\lesssim 1.1\times10^{36}$ erg s$^{-1}$ and $L_{\rm X}\lesssim 2.6\times10^{36}$ erg s$^{-1}$ (3$-$78 keV) for SLX 1744$-$299 and SLX 1744$-$300, respectively. The corresponding mass-accretion rates, when compared with the critical values from the disc instability model, favour $P_{\rm orb}\lesssim 90$ min and $P_{\rm orb}\lesssim 105-155$ min. Although both limits are formally compatible with the UCXB regime, the case of SLX 1744$-$299 appears significantly more compelling, also considering the previously reported intermediate-duration burst.

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 paper reports the first spatially resolved NuSTAR observation above 10 keV of the Galactic Centre pair SLX 1744-299 and SLX 1744-300. Both sources are found in the hard state via timing (rms variability) and spectral (thermal Comptonisation) analysis, with SLX 1744-300 showing two Type-I bursts. Using previously reported distance upper limits, the authors derive persistent luminosity upper bounds L_X ≲ 1.1×10^36 erg s^{-1} (SLX 1744-299) and ≲ 2.6×10^36 erg s^{-1} (SLX 1744-300) in 3-78 keV, convert these to mass-accretion rate upper limits, and compare against disc instability model critical rates to obtain P_orb ≲ 90 min and ≲ 105-155 min, favouring an ultracompact classification.

Significance. If the distance upper limits remain valid for the individually resolved sources and the DIM critical rates apply without additional systematics, the work supplies new hard-state constraints and orbital-period limits on two candidate UCXBs near the Galactic Centre. The resolved flux ratio (~1.15 in 3-78 keV) and differing variability behaviours are useful observational results independent of the period inference.

major comments (2)
  1. [abstract and luminosity derivation section] The luminosity upper limits and subsequent P_orb constraints (abstract and the paragraph combining results with prior distance limits) rest on distance upper bounds derived from spatially unresolved observations. The manuscript does not re-derive or validate these limits using the new resolved fluxes (ratio ~1.15); if the true distances exceed the adopted bounds, the L_X and Ṁ upper limits increase and the orbital-period constraints are removed. This is load-bearing for the central UCXB claim.
  2. [luminosity and accretion-rate comparison paragraph] The comparison of derived Ṁ upper limits to DIM critical accretion rates (same paragraph) adopts literature critical values without independent verification or discussion of possible systematics for these specific systems; the resulting P_orb bounds are therefore model-dependent in a way not quantified.
minor comments (2)
  1. [spectral analysis section] The flux ratio is stated as ~1.15 in 3-78 keV and ~1.3 when extrapolated to 0.5-10 keV; clarify whether the extrapolation uses the same Comptonisation parameters for both sources.
  2. Notation for mass-accretion rate should be consistent (e.g., Ṁ vs. Ṁ_dot) throughout the text and abstract.

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 indicate where revisions will be made.

read point-by-point responses

  1. Referee: [abstract and luminosity derivation section] The luminosity upper limits and subsequent P_orb constraints (abstract and the paragraph combining results with prior distance limits) rest on distance upper bounds derived from spatially unresolved observations. The manuscript does not re-derive or validate these limits using the new resolved fluxes (ratio ~1.15); if the true distances exceed the adopted bounds, the L_X and Ṁ upper limits increase and the orbital-period constraints are removed. This is load-bearing for the central UCXB claim.

    Authors: The distance upper limits are taken from the existing literature on the unresolved pair. Our resolved observation yields a flux ratio of only ~1.15 (3-78 keV), rising to ~1.3 when extrapolated to 0.5-10 keV. Given the sources' close projected separation and presumed common distance, this modest ratio means the individual luminosity upper limits differ from the combined-flux limits by at most this factor. We will revise the manuscript to state this explicitly and note that the resulting P_orb constraints remain valid within the quoted uncertainties. revision: yes

  2. Referee: [luminosity and accretion-rate comparison paragraph] The comparison of derived Ṁ upper limits to DIM critical accretion rates (same paragraph) adopts literature critical values without independent verification or discussion of possible systematics for these specific systems; the resulting P_orb bounds are therefore model-dependent in a way not quantified.

    Authors: The critical accretion rates are adopted from standard references in the disc instability model literature. We agree that an explicit discussion of model assumptions would improve clarity. In the revised manuscript we will expand the relevant paragraph to summarise the main systematics (e.g., hydrogen mass fraction, disc truncation radius) and to emphasise that the derived P_orb upper limits are indicative within the DIM framework. revision: yes

Circularity Check

0 steps flagged

No significant circularity; derivation relies on external inputs

full rationale

The paper's chain obtains resolved fluxes from new NuSTAR data, combines them with previously reported (external) distance upper limits to produce L_X ≲ 1.1×10^36 and ≲ 2.6×10^36 erg s^{-1}, converts to \dot{M} upper bounds, and compares those bounds against critical accretion rates taken from the disc instability model in the literature to obtain P_orb limits. No self-definitional equations, no fitted parameters renamed as predictions, and no load-bearing self-citations appear in the provided derivation steps. The result is therefore not forced by construction from the paper's own inputs.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

No new free parameters or invented entities; the analysis rests on standard Comptonisation spectral models, the disc instability framework, and external distance upper limits.

axioms (1)
  • domain assumption Critical mass-accretion rates from the disc instability model as a function of orbital period
    Invoked to convert observed luminosities into orbital-period upper limits.

pith-pipeline@v0.9.1-grok · 5975 in / 1403 out tokens · 30002 ms · 2026-06-27T12:09:47.721298+00:00 · methodology

discussion (0)

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

Reference graph

Works this paper leans on

62 extracted references · 5 canonical work pages · 2 internal anchors

  1. [1]

    2020, MNRAS, 494, 2509

    Alizai, K., Chenevez, J., Brandt, S., & Lund, N. 2020, MNRAS, 494, 2509

    2020

  2. [2]

    L., Linares, M., Homan, J., & Chakrabarty, D

    Allen, J. L., Linares, M., Homan, J., & Chakrabarty, D. 2015, ApJ, 801, 10

    2015

  3. [3]

    2023, Living Reviews in Relativity, 26, 2 Armas Padilla, M., Corral-Santana, J

    Amaro-Seoane, P., Andrews, J., Arca Sedda, M., et al. 2023, Living Reviews in Relativity, 26, 2 Armas Padilla, M., Corral-Santana, J. M., Borghese, A., et al. 2023, A&A, 677, A186 Armas Padilla, M., Degenaar, N., & Wijnands, R. 2013a, MNRAS, 434, 1586 Armas Padilla, M., Ponti, G., De Marco, B., Muñoz-Darias, T., & Haberl, F. 2018, MNRAS, 473, 3789 Armas P...

    2023

  4. [4]

    M., Sivakoff, G

    Arnason, R. M., Sivakoff, G. R., Heinke, C. O., Cohn, H. N., & Lugger, P. M. 2015, ApJ, 807, 52

    2015

  5. [5]

    Arnaud, K. A. 1996, in Astronomical Society of the Pacific Conference Series, V ol. 101, Astronomical Data Analysis Software and Systems V , ed. G. H. Jacoby & J. Barnes, 17

    1996

  6. [6]

    2018, HENDRICS: High ENergy Data Reduction Interface from the Command Shell, Astrophysics Source Code Library, record ascl:1805.019

    Bachetti, M. 2018, HENDRICS: High ENergy Data Reduction Interface from the Command Shell, Astrophysics Source Code Library, record ascl:1805.019

    2018

  7. [7]

    & Huppenkothen, D

    Bachetti, M. & Huppenkothen, D. 2018, ApJ, 853, L21

    2018

  8. [8]

    & Degenaar, N

    Bahramian, A. & Degenaar, N. 2023, in Handbook of X-ray and Gamma-ray Astrophysics. Edited by Cosimo Bambi and Andrea Santangelo, 120

    2023

  9. [9]

    O., Tudor, V ., et al

    Bahramian, A., Heinke, C. O., Tudor, V ., et al. 2017, MNRAS, 467, 2199

    2017

  10. [10]

    2024, A&A, 688, A214

    Ballhausen, R., Thalhammer, P., Pradhan, P., et al. 2024, A&A, 688, A214

    2024

  11. [11]

    Blackburn, J. K. 1995, in Astronomical Society of the Pacific Conference Se- ries, V ol. 77, Astronomical Data Analysis Software and Systems IV , ed. R. A

    1995

  12. [12]

    The NuSTAR view of Ultra-Compact X-ray Binaries

    Borghese, A., Armas Padilla, M., & Muñoz-Darias, T. 2026, arXiv e-prints, arXiv:2604.13187

    work page internal anchor Pith review Pith/arXiv arXiv 2026

  13. [13]

    J., Gilfanov, M., & Sunyaev, R

    Burke, M. J., Gilfanov, M., & Sunyaev, R. 2017, MNRAS, 466, 194

    2017

  14. [14]

    V ., Grebenev, S

    Chelovekov, I. V ., Grebenev, S. A., Mereminskiy, I. A., & Prosvetov, A. V . 2017, Astronomy Letters, 43, 781

    2017

  15. [15]

    M., Han, Z., & Chen, X

    Chen, H.-L., Tauris, T. M., Han, Z., & Chen, X. 2021, MNRAS, 503, 3540

    2021

  16. [16]

    P., & Dubus, G

    Coriat, M., Fender, R. P., & Dubus, G. 2012, MNRAS, 424, 1991

    2012

  17. [17]

    2004, Nuclear Physics B Proceedings Supplements, 132, 435

    Cumming, A. 2004, Nuclear Physics B Proceedings Supplements, 132, 435

    2004

  18. [18]

    Degenaar, N., Koljonen, K. I. I., Chakrabarty, D., et al. 2016, MNRAS, 456, 4256

    2016

  19. [19]

    M., Chakrabarty, D., et al

    Degenaar, N., Miller, J. M., Chakrabarty, D., et al. 2015, MNRAS, 451, L85

    2015

  20. [20]

    Degenaar, N., Wijnands, R., & Miller, J. M. 2013, ApJ, 767, L31

    2013

  21. [21]

    M., Grinberg, V ., Fürst, F., et al

    Diez, C. M., Grinberg, V ., Fürst, F., et al. 2023, A&A, 674, A147

    2023

  22. [22]

    2007, A&A Rev., 15, 1

    Done, C., Gierli´nski, M., & Kubota, A. 2007, A&A Rev., 15, 1

    2007

  23. [23]

    2024, arXiv e-prints, arXiv:2401.11931

    Fortin, F., Kalsi, A., García, F., & Chaty, S. 2024, arXiv e-prints, arXiv:2401.11931

    work page arXiv 2024

  24. [24]

    K., Muno, M

    Galloway, D. K., Muno, M. P., Hartman, J. M., Psaltis, D., & Chakrabarty, D. 2008, ApJS, 179, 360

    2008

  25. [25]

    & Weare, J

    Goodman, J. & Weare, J. 2010, Communications in Applied Mathematics and Computational Science, 5, 65

    2010

  26. [26]

    P., et al

    Grefenstette, B., Brightman, M., Earnshaw, H. P., et al. 2022, arXiv e-prints, arXiv:2206.04058

    work page arXiv 2022

  27. [27]

    A., Craig, W

    Harrison, F. A., Craig, W. W., Christensen, F. E., et al. 2013, ApJ, 770, 103

    2013

  28. [28]

    L., et al

    Huppenkothen, D., Bachetti, M., Stevens, A. L., et al. 2019, ApJ, 881, 39 in’t Zand, J. J. M., Galloway, D. K., & Ballantyne, D. R. 2011, A&A, 525, A111 in’t Zand, J. J. M., Jonker, P. G., & Markwardt, C. B. 2007, A&A, 465, 953

    2019

  29. [29]

    E., Middleditch, J., et al

    Kawai, N., Fenimore, E. E., Middleditch, J., et al. 1988, ApJ, 330, 130

    1988

  30. [30]

    E., An, H., Barrière, N., et al

    Koglin, J. E., An, H., Barrière, N., et al. 2011, in Society of Photo-Optical Instru- mentation Engineers (SPIE) Conference Series, V ol. 8147, Society of Photo- Optical Instrumentation Engineers (SPIE) Conference Series, ed. S. L. O’Dell & G. Pareschi, 81470J Article number, page 9 of 10 A&A proofs:manuscript no. aa59519-26

    2011

  31. [31]

    1998, PASJ, 50, 667 La Monaca, F., Di Marco, A., Poutanen, J., et al

    Kubota, A., Tanaka, Y ., Makishima, K., et al. 1998, PASJ, 50, 667 La Monaca, F., Di Marco, A., Poutanen, J., et al. 2024, ApJ, 960, L11

    1998

  32. [32]

    2001, New A Rev., 45, 449

    Lasota, J.-P. 2001, New A Rev., 45, 449

    2001

  33. [33]

    P., Dubus, G., & Kruk, K

    Lasota, J. P., Dubus, G., & Kruk, K. 2008, A&A, 486, 523

    2008

  34. [34]

    Lewin, W. H. G., van Paradijs, J., & Taam, R. E. 1993, Space Sci. Rev., 62, 223

    1993

  35. [35]

    A., & Homan, J

    Lin, D., Remillard, R. A., & Homan, J. 2007, ApJ, 667, 1073

    2007

  36. [36]

    M., Miller, J

    Ludlam, R. M., Miller, J. M., Bachetti, M., et al. 2017, ApJ, 836, 140

    2017

  37. [37]

    K., Forster, K., Grefenstette, B., Harrison, F

    Madsen, K. K., Forster, K., Grefenstette, B., Harrison, F. A., & Miyasaka, H. 2022, Journal of Astronomical Telescopes, Instruments, and Systems, 8, 034003

    2022

  38. [38]

    K., Grefenstette, B

    Madsen, K. K., Grefenstette, B. W., Pike, S., et al. 2020, arXiv e-prints, arXiv:2005.00569

    work page arXiv 2020

  39. [39]

    K., Harrison, F

    Madsen, K. K., Harrison, F. A., Markwardt, C. B., et al. 2015, ApJS, 220, 8

    2015

  40. [40]

    1986, ApJ, 308, 635

    Makishima, K., Maejima, Y ., Mitsuda, K., et al. 1986, ApJ, 308, 635

    1986

  41. [41]

    2017, A&A, 603, A39

    Matranga, M., Papitto, A., Di Salvo, T., et al. 2017, A&A, 603, A39

    2017

  42. [42]

    2002, ApJ, 564, L81

    Menou, K., Perna, R., & Hernquist, L. 2002, ApJ, 564, L81

    2002

  43. [43]

    1984, PASJ, 36, 741

    Mitsuda, K., Inoue, H., Koyama, K., et al. 1984, PASJ, 36, 741

    1984

  44. [44]

    G., Sakano, M., & Tsuboi, Y

    Mori, H., Maeda, Y ., Pavlov, G. G., Sakano, M., & Tsuboi, Y . 2005, Advances in Space Research, 35, 1137 Muñoz-Darias, T., Fender, R. P., Motta, S. E., & Belloni, T. M. 2014, MNRAS, 443, 3270 Muñoz-Darias, T., Motta, S., & Belloni, T. M. 2011, MNRAS, 410, 679

    2005

  45. [45]

    Binaries as Sources of Gravitational Waves

    Nelemans, G. 2018, arXiv e-prints, arXiv:1807.01060

    work page internal anchor Pith review Pith/arXiv arXiv 2018

  46. [46]

    & Jonker, P

    Nelemans, G. & Jonker, P. G. 2010, New A Rev., 54, 87

    2010

  47. [47]

    & Sienkiewicz, R

    Paczynski, B. & Sienkiewicz, R. 1981, ApJ, 248, L27

    1981

  48. [48]

    2021, A&A, 650, A42

    Pavlinsky, M., Tkachenko, A., Levin, V ., et al. 2021, A&A, 650, A42

    2021

  49. [49]

    N., Grebenev, S

    Pavlinsky, M. N., Grebenev, S. A., & Sunyaev, R. A. 1994, ApJ, 425, 110

    1994

  50. [50]

    C., & Webbink, R

    Rappaport, S., Joss, P. C., & Webbink, R. F. 1982, ApJ, 254, 616

    1982

  51. [51]

    K., Foster, A

    Skinner, G. K., Foster, A. J., Willmore, A. P., & Eyles, C. J. 1990, MNRAS, 243, 72

    1990

  52. [52]

    K., Willmore, A

    Skinner, G. K., Willmore, A. P., Eyles, C. J., Bertram, D., & Church, M. J. 1987, Nature, 330, 544

    1987

  53. [53]

    2021, MNRAS, 507, 330

    Stoop, M., van den Eijnden, J., Degenaar, N., et al. 2021, MNRAS, 507, 330

    2021

  54. [54]

    Tauris, T. M. 2018, Phys. Rev. Lett., 121, 131105 van den Eijnden, J., Degenaar, N., Pinto, C., et al. 2018, MNRAS, 475, 2027 van Haaften, L. M., Nelemans, G., V oss, R., et al. 2013, A&A, 552, A69

    2018

  55. [55]

    & van den Heuvel, E

    Verbunt, F. & van den Heuvel, E. P. J. 1995, in X-ray Binaries, 457–494

    1995

  56. [56]

    A., Ferland, G

    Verner, D. A., Ferland, G. J., Korista, K. T., & Yakovlev, D. G. 1996, ApJ, 465, 487

    1996

  57. [57]

    2015, MNRAS, 454, 1371

    Wijnands, R., Degenaar, N., Armas Padilla, M., et al. 2015, MNRAS, 454, 1371

    2015

  58. [58]

    2000, ApJ, 542, 914

    Wilms, J., Allen, A., & McCray, R. 2000, ApJ, 542, 914

    2000

  59. [59]

    2024, A&A, 686, A95

    Zalot, N., Sokolova-Lapa, E., Stierhof, J., et al. 2024, A&A, 686, A95

    2024

  60. [60]

    1995, ApJ, 439, 849

    Zampieri, L., Turolla, R., Zane, S., & Treves, A. 1995, ApJ, 439, 849

    1995

  61. [61]

    A., Johnson, W

    Zdziarski, A. A., Johnson, W. N., & Magdziarz, P. 1996, MNRAS, 283, 193

    1996

  62. [62]

    2012, Research in Astronomy and Astro- physics, 12, 1526 ˙Zycki, P

    Zhu, C.-H., Lü, G.-L., & Wang, Z.-J. 2012, Research in Astronomy and Astro- physics, 12, 1526 ˙Zycki, P. T., Done, C., & Smith, D. A. 1999, MNRAS, 309, 561 Article number, page 10 of 10

    2012