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arxiv: 2507.13278 · v2 · submitted 2025-07-17 · 🌌 astro-ph.HE

The pulsar wind nebula around B1853+01 in X-rays

Xiying Zhang , Pol Bordas , Samar Safi-Harb , Kazushi Iwasawa This is my paper

Pith reviewed 2026-05-19 04:28 UTC · model grok-4.3

classification 🌌 astro-ph.HE
keywords pulsar wind nebulaPSR B1853+01X-ray emissionescaping particlesbow-shock PWNW44 supernova remnantspectral analysisdiffuse halo
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The pith

High-energy particles escape the pulsar wind nebula around PSR B1853+01 to form an X-ray outflow and surrounding halo.

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

The paper presents X-ray observations from Chandra, XMM-Newton, and NuSTAR of the pulsar wind nebula tied to the fast-moving PSR B1853+01 inside the W44 supernova remnant. These data reveal an outflow extending about one arcminute ahead of the pulsar and a larger faint diffuse emission structure surrounding the entire nebula. Spatially resolved spectra show the outflow has a significantly harder power-law index than the pulsar or its trailing tail. The authors conclude that both features arise from high-energy particles leaving the nebula, consistent with ideas proposed for similar bow-shock pulsar wind nebulae that display jet-like structures or TeV halos.

Core claim

The central claim is that the outflow structure ahead of PSR B1853+01 and the surrounding halo-like X-ray emission are produced by high-energy particles escaping the pulsar wind nebula, as indicated by the harder spectral index of approximately 1.24 in the outflow compared to 1.87 for the pulsar and 2.01 for the tail.

What carries the argument

Spatially-resolved power-law spectral fits to carefully chosen extraction regions that isolate the outflow and compare its photon index to the pulsar and tail.

If this is right

  • Jet-like structures in other bow-shock PWNe may result from the same particle escape process.
  • The halo-like emission around this PWN may be analogous to TeV halos reported for similar systems.
  • High-energy particles can propagate several parsecs beyond the main nebula along the pulsar's direction of motion.
  • This escape mechanism would link X-ray morphologies directly to potential gamma-ray signatures in bow-shock PWNe.

Where Pith is reading between the lines

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

  • Targeted TeV observations of the outflow and halo regions could directly test for the expected high-energy counterpart emission.
  • Diffusion models for particle transport could be calibrated on this system to predict halo extents around other PWNe.
  • If the escape is common, total energy budgets for PWNe and their contribution to galactic cosmic rays would need upward revision.

Load-bearing premise

The harder spectral index measured in the outflow region demonstrates escaping particles rather than projection effects, background contamination, or a different emission mechanism.

What would settle it

Re-extraction of spectra from the outflow region using alternative background subtraction or region boundaries that removes the hardness difference, or the lack of any correlated high-energy gamma-ray emission from the same structures.

Figures

Figures reproduced from arXiv: 2507.13278 by Kazushi Iwasawa, Pol Bordas, Samar Safi-Harb, Xiying Zhang.

Figure 1
Figure 1. Figure 1: XMM-Newton exposure-corrected mosaic images of SNR W44 in hard (4.0-8.0 keV) X-ray bands. Left: in the FoV of W44 with the SNR radio contours in yellow (radio fits file obtained from SNRCat at http://snrcat.physics. umanitoba.ca/SNRrecord.php?id=G034.7m00.4) and the soft (0.5-4.0 keV) X-ray contour of W44 in cyan. The position of PSR B1853+01 is marked by a black cross with a white arrow indicating the dir… view at source ↗
Figure 2
Figure 2. Figure 2: Images of PSR B1853+01 (position marked by a black cross) and its surrounding emission. [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Merged (FPMA+FPMB) NuSTAR images obtained at increasing energy bands. Images are smoothed with a Gaussian kernel of r=8 pixels and σ=4 pixels. Position of PSR B1853+01 is marked by a black cross while the position of a nearby source 2CXO J185613.6+011207 is marked by a black X. Left: The 4.0-10.0 keV image shows an extended emission coincides with the position of PSR B1853+01, exhibiting a spindle-like sha… view at source ↗
Figure 4
Figure 4. Figure 4: Chandra 2-7 keV on-axis counts image. The image is unbinned and unsmoothed. Both the circle and the annulus are centered at the pulsar position detected by Chandra. The magenta circle is of radius 1.8′′and is used for pulsar spectra extraction. The green dashed annulus has radii of 3 ′′and 6′′and is used as background region for the pulsar. sar’s proper motion direction (protruding to the northeast just be… view at source ↗
Figure 5
Figure 5. Figure 5: Merged Chandra broad band (0.5-7.0 keV) flux im￾age with extraction regions used for spectral extraction overlaid. The image is unbinned yet smoothed with a Gaus￾sian function with radius r=3 pixel and sigma σ=1.5 im￾age pixels. Weighted spectra have been extracted from tail (solid cyan) region with pulsar (r=3") excluded, using bkg1 region (dashed green) as background region, and from an￾tenna region (sol… view at source ↗
Figure 6
Figure 6. Figure 6: Left: 4′×4 ′ XMM-Newton pn image in 4.0-8.0 keV band (merged from Obs. 0721630101, 0721630201, and 0721630301). The extraction regions for the tail region (solid cyan; crossed green circle region representing PSR B1853+01 was excluded from the CN/tail spectral analysis) and the outflow region (solid magenta) are shown. The tail region can be further split into two subregions: CN and trail (separated by the… view at source ↗
read the original abstract

We report on the results of a comprehensive analysis of X-ray observations with \textit{Chandra}, \textit{XMM-Newton} and \textit{NuSTAR} of the pulsar wind nebula (PWN) associated with PSR B1853+01, located inside the W44 supernova remnant (SNR). Previous X-ray observations unveiled the presence of a fast-moving pulsar, PSR B1853+01, at the southern edge of the W44 thermal X-ray emission region, as well as an elongated tail structure trailing the pulsar. Our analysis reveals, in addition, an ``outflow'' feature ahead of the pulsar extending for about 1\arcmin~($\sim$1.0 pc at a distance of 3.2 kpc). At larger scales, the entire PWN seems to be surrounded by a faint, diffuse X-ray emission structure. The southern part of this structure displays the same unusual morphology as the ``outflow'' feature and extends along $\sim$6\arcmin~($\sim$5 pc) in the direction of the pulsar proper motion. In this report, a spatially-resolved spectral analysis for different extended regions around PSR B1853+01 is carried out. For an updated value of the column density of $0.65_{-0.42}^{+0.46} \times 10^{22} ~\textrm{cm}^{-2}$, a power-law fit to the ``outflow'' region yields a spectral index $\Gamma \approx 1.24_{-0.24}^{+0.23}$, which is significantly harder than that of the pulsar ($\Gamma \approx 1.87_{-0.43}^{+0.48}$) and the pulsar tail ($\Gamma \approx 2.01_{-0.38}^{+0.39}$). We argue that both the ``outflow'' structure and the surrounding halo-like X-ray emission might be produced by high-energy particles escaping the PWN around PSR B1853+01, a scenario recently suggested also for other bow-shock PWNe with jet-like structures and/or TeV halos.

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 presents a multi-instrument X-ray analysis (Chandra, XMM-Newton, NuSTAR) of the pulsar wind nebula associated with PSR B1853+01 inside SNR W44. It identifies a previously unreported 'outflow' feature extending ~1 arcmin ahead of the pulsar and a larger-scale faint diffuse halo-like emission surrounding the PWN. Spatially resolved spectral fitting yields a hard power-law index Γ ≈ 1.24 for the outflow region, compared to Γ ≈ 1.87 for the pulsar and Γ ≈ 2.01 for the tail, with an updated absorbing column N_H = 0.65_{-0.42}^{+0.46} × 10^{22} cm^{-2}. The authors interpret both the outflow and halo as signatures of high-energy particles escaping the PWN, analogous to structures seen in other bow-shock PWNe.

Significance. If the reported spectral hardening is robust, the result provides observational support for particle escape in bow-shock PWNe and offers a unified explanation for jet-like X-ray features and TeV halos. The multi-instrument dataset and spatially resolved spectroscopy are strengths, enabling direct comparison of spectral properties across morphological components. The work adds to the growing sample of PWNe where escaping particles are invoked, with potential implications for cosmic-ray acceleration and diffusion models.

major comments (2)
  1. [Spectral analysis] Spectral analysis section: The photon index difference between the outflow region (Γ ≈ 1.24_{-0.24}^{+0.23}) and the pulsar (Γ ≈ 1.87_{-0.43}^{+0.48}) is only ~1.2σ given the quoted uncertainties and the strong correlation with the poorly constrained N_H. This marginal significance undermines the central claim that the hardness demonstrates a distinct escaping high-energy particle population rather than statistical fluctuation, background subtraction effects, or projection.
  2. [Morphological analysis] Morphological and region selection discussion: The interpretation that the outflow and southern halo are produced by escaping particles assumes the chosen extraction regions cleanly isolate these features without significant contamination from the SNR or unrelated emission. No quantitative assessment of region boundaries, background modeling, or alternative explanations (e.g., projection effects or different emission mechanisms) is provided to test this assumption.
minor comments (2)
  1. [Abstract] The abstract and text should explicitly state the statistical significance of the spectral index difference rather than describing it as 'significantly harder'.
  2. [Figures] Figure captions for the X-ray images should include the exact energy bands, exposure times, and smoothing scales used to define the outflow and halo features.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful and constructive review of our manuscript. We address each major comment below, acknowledging where the statistical evidence is limited and outlining revisions to improve clarity and robustness.

read point-by-point responses

  1. Referee: [Spectral analysis] Spectral analysis section: The photon index difference between the outflow region (Γ ≈ 1.24_{-0.24}^{+0.23}) and the pulsar (Γ ≈ 1.87_{-0.43}^{+0.48}) is only ~1.2σ given the quoted uncertainties and the strong correlation with the poorly constrained N_H. This marginal significance undermines the central claim that the hardness demonstrates a distinct escaping high-energy particle population rather than statistical fluctuation, background subtraction effects, or projection.

    Authors: We agree that the photon-index difference is statistically marginal at roughly 1.2σ and that the shared N_H introduces correlated uncertainties that limit the strength of the claim when considered in isolation. The same N_H was applied to all regions to enable direct comparison, and the outflow remains the hardest component in the data. We will revise the text to replace 'significantly harder' with 'harder' and add an explicit discussion of the statistical significance, possible systematics from background subtraction, and the fact that the spectral trend is only one element supporting the escaping-particle interpretation alongside the morphology. revision: partial

  2. Referee: [Morphological analysis] Morphological and region selection discussion: The interpretation that the outflow and southern halo are produced by escaping particles assumes the chosen extraction regions cleanly isolate these features without significant contamination from the SNR or unrelated emission. No quantitative assessment of region boundaries, background modeling, or alternative explanations (e.g., projection effects or different emission mechanisms) is provided to test this assumption.

    Authors: The regions were defined from the Chandra image to follow the observed morphology: the outflow region placed immediately ahead of the pulsar along its proper-motion vector and the halo region enclosing the larger-scale diffuse emission. Background was taken from nearby source-free areas. We acknowledge that the manuscript lacks a quantitative evaluation of contamination or alternative scenarios. In revision we will expand the methods section with explicit region coordinates, an estimate of possible SNR contamination, and a short discussion of projection effects versus the escaping-particle model, explaining why the latter is preferred given the spectral hardness and similarities to other bow-shock PWNe. revision: yes

Circularity Check

0 steps flagged

No circularity: results from new X-ray data and standard spectral fits

full rationale

The paper reports new Chandra, XMM-Newton and NuSTAR observations of the PWN around PSR B1853+01, performs spatially-resolved power-law spectral fits with an updated N_H value, and directly compares the resulting photon indices (outflow Γ≈1.24, pulsar Γ≈1.87, tail Γ≈2.01). The interpretation that harder emission in the outflow and halo may indicate escaping particles is presented as a data-driven suggestion referencing similar features in other PWNe; no step reduces a claimed prediction or first-principles result to a quantity defined by the authors' own prior fits, self-citations, or ansatzes. The derivation chain is fully self-contained against the external observational data.

Axiom & Free-Parameter Ledger

2 free parameters · 1 axioms · 1 invented entities

The interpretation depends on fitted spectral parameters and the assumption that spectral hardness directly traces an escaping particle population.

free parameters (2)
  • absorbing column density = 0.65 x 10^22 cm^-2
    Updated value of 0.65e22 cm^-2 fitted to the spectral data of the extended regions.
  • power-law photon index for outflow = 1.24
    Fitted value Gamma approx 1.24 used to argue for a distinct particle population.
axioms (1)
  • domain assumption X-ray emission in PWNe is dominated by synchrotron radiation from relativistic electrons following a power-law energy distribution.
    Invoked when fitting power-law models to extract spectral indices that are then compared across regions.
invented entities (1)
  • escaping high-energy particles no independent evidence
    purpose: To explain the hard-spectrum outflow and surrounding halo morphology.
    Postulated mechanism without independent detection outside the X-ray data presented.

pith-pipeline@v0.9.0 · 5930 in / 1376 out tokens · 65674 ms · 2026-05-19T04:28:21.141860+00:00 · methodology

discussion (0)

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Works this paper leans on

68 extracted references · 68 canonical work pages

  1. [1]

    2025, A&A, 693, A255

    Abe, S., Abhir, J., Abhishek, A., et al. 2025, A&A, 693, A255

    work page 2025

  2. [2]

    X., et al

    Aharonian, F., An, Q., Axikegu, Bai, L. X., et al. 2021, Phys. Rev. Lett., 126, 241103

    work page 2021

  3. [3]

    Aharonian, F. A. 1995, Nuclear Physics B Proceedings Supplements, 39, 193

    work page 1995

  4. [4]

    A., Atoyan, A

    Aharonian, F. A., Atoyan, A. M., & Kifune, T. 1997, MNRAS, 291, 162

    work page 1997

  5. [5]

    T., et al

    Archer, A., Bangale, P., Bartkoske, J. T., et al. 2025, ApJ, 983, 73

    work page 2025

  6. [6]

    Arnaud, K. A. 1996, in Astronomical Society of the Pacific Conference

    work page 1996

  7. [7]

    2008, A&A, 490, L3

    Bandiera, R. 2008, A&A, 490, L3

    work page 2008

  8. [8]

    Barkov, M. V. & Lyutikov, M. 2019, MNRAS, 489, L28

    work page 2019

  9. [9]

    V., Lyutikov, M., Klingler, N., & Bordas, P

    Barkov, M. V., Lyutikov, M., Klingler, N., & Bordas, P. 2019, MN- RAS, 485, 2041

    work page 2019

  10. [10]

    Bogovalov, S. V. & Khangoulian, D. V. 2002, MNRAS, 336, L53 Bordas,P.,Zhang,X.,Bosch-Ramon,V.,&Paredes,J.M.2021,A&A, 654, A4

    work page 2002

  11. [11]

    2024, ApJS, 271, 25

    Cao, Z., Aharonian, F., An, Q., et al. 2024, ApJS, 271, 25

    work page 2024

  12. [12]

    L., Murray, J

    Caswell, J. L., Murray, J. D., Roger, R. S., Cole, D. J., & Cooke, D. J. 1975, A&A, 45, 239

    work page 1975

  13. [13]

    H., Green, A

    Clark, D. H., Green, A. J., & Caswell, J. L. 1975, Australian Journal of Physics Astrophysical Supplement, 37, 75

    work page 1975

  14. [14]

    J., Frail, D

    Claussen, M. J., Frail, D. A., Goss, W. M., & Gaume, R. A. 1997, ApJ, 489, 143 de Jager, O. C. & Mastichiadis, A. 1997, ApJ, 482, 874 de Vries, M. & Romani, R. W. 2022, ApJ, 928, 39

    work page 1997

  15. [15]

    A., Giacani, E

    Frail, D. A., Giacani, E. B., Goss, W. M., & Dubner, G. 1996, ApJ, 464, L165

    work page 1996

  16. [16]

    M., Chatterjee, S., Slane, P

    Gaensler, B. M., Chatterjee, S., Slane, P. O., et al. 2006, ApJ, 648, 1037

    work page 2006

  17. [17]

    P., Bautz, M

    Garmire, G. P., Bautz, M. W., Ford, P. G., Nousek, J. A., & Ricker, George R., J. 2003, in Society of Photo-Optical Instrumentation Engineers(SPIE)ConferenceSeries,Vol.4851,X-RayandGamma- RayTelescopesandInstrumentsforAstronomy.,ed.J.E.Truemper & H. D. Tananbaum, 28–44

    work page 2003

  18. [18]

    Giacinti, G., Mitchell, A. M. W., López-Coto, R., et al. 2020, A&A, 636, A113

    work page 2020

  19. [19]

    & Julian, W

    Goldreich, P. & Julian, W. H. 1969, ApJ, 157, 869 H. E. S. S. Collaboration, Abdalla, H., Abramowski, A., et al. 2018, A&A, 612, A1

    work page 1969

  20. [20]

    A., Craig, W

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

    work page 2013

  21. [21]

    2006, in ESA Special

    Harrus, I., Smith, R., Slane, P., & Hughes, J. 2006, in ESA Special

    work page 2006

  22. [22]

    604, The X-ray Universe 2005, ed

    Publication, Vol. 604, The X-ray Universe 2005, ed. A. Wilson, 369

    work page 2005

  23. [23]

    M., Hughes, J

    Harrus, I. M., Hughes, J. P., & Helfand, D. J. 1996, ApJ, 464, L161

    work page 1996

  24. [24]

    M., Hughes, J

    Harrus, I. M., Hughes, J. P., Singh, K. P., Koyama, K., & Asaoka, I. 1997, ApJ, 488, 781

    work page 1997

  25. [25]

    2022, ApJ, 925, 165

    Heywood, I., Rammala, I., Camilo, F., et al. 2022, ApJ, 925, 165

    work page 2022

  26. [26]

    Hui, C. Y. & Becker, W. 2007, A&A, 467, 1209

    work page 2007

  27. [27]

    Hui, C. Y. & Becker, W. 2008, A&A, 486, 485

    work page 2008

  28. [28]

    Jacoby, B. A. & Wolszczan, A. 1999, in Pulsar Timing, General Rel- ativity and the Internal Structure of Neutron Stars, ed. Z. Arzou- manian, F. Van der Hooft, & E. P. J. van den Heuvel, 157

    work page 1999

  29. [29]

    P., Dong, H., & Wang, Q

    Johnson, S. P., Dong, H., & Wang, Q. D. 2009, MNRAS, 399, 1429

    work page 2009

  30. [30]

    R., Smith, A., & Angelini, L

    Jones, L. R., Smith, A., & Angelini, L. 1993, MNRAS, 265, 631

    work page 1993

  31. [31]

    & Pavlov, G

    Kargaltsev, O. & Pavlov, G. G. 2008, in American Institute of Physics Conference Series, Vol. 983, 40 Years of Pulsars: Millisecond Pul- sars, Magnetars and More, ed. C. Bassa, Z. Wang, A. Cumming, & V. M. Kaspi, 171–185

    work page 2008

  32. [32]

    G., Klingler, N., & Rangelov, B

    Kargaltsev, O., Pavlov, G. G., Klingler, N., & Rangelov, B. 2017, Journal of Plasma Physics, 83, 635830501

    work page 2017

  33. [33]

    Zinchenko, I. I. 2024, MNRAS, 527, 5683 Kirk,J.G.,Lyubarsky,Y.,&Petri,J.2009,inAstrophysicsandSpace Science Library, Vol. 357, Astrophysics and Space Science Library, ed. W. Becker, 421

    work page 2024

  34. [34]

    H., Lu, F

    Li, X. H., Lu, F. J., & Li, T. P. 2005, ApJ, 628, 931

    work page 2005

  35. [35]

    2017, Phys

    Linden, T., Auchettl, K., Bramante, J., et al. 2017, Phys. Rev. D, 96, 103016

    work page 2017

  36. [36]

    2022, MNRAS, 510, 4952

    Liu, M., Hu, Y., & Lazarian, A. 2022, MNRAS, 510, 4952

    work page 2022

  37. [37]

    Lyubarsky, Y. E. 2002, MNRAS, 329, L34

    work page 2002

  38. [38]

    M., Gaensler, B

    Migliazzo, J. M., Gaensler, B. M., Backer, D. C., et al. 2002, ApJ, 567, L141

    work page 2002

  39. [39]

    K., Nobukawa, M., Koyama, K., et al

    Nobukawa, K. K., Nobukawa, M., Koyama, K., et al. 2018, ApJ, 854, 87

    work page 2018

  40. [40]

    2020, ApJ, 890, 62

    Okon, H., Tanaka, T., Uchida, H., et al. 2020, ApJ, 890, 62

    work page 2020

  41. [41]

    & Bucciantini, N

    Olmi, B. & Bucciantini, N. 2019, MNRAS, 490, 3608

    work page 2019

  42. [42]

    2014, A&A, 562, A122

    Pavan, L., Bordas, P., Pühlhofer, G., et al. 2014, A&A, 562, A122

    work page 2014

  43. [43]

    2016, A&A, 591, A91

    Pavan, L., Pühlhofer, G., Bordas, P., et al. 2016, A&A, 591, A91

    work page 2016

  44. [44]

    2020, ApJ, 896, L23

    Peron, G., Aharonian, F., Casanova, S., Zanin, R., & Romoli, C. 2020, ApJ, 896, L23

    work page 2020

  45. [45]

    D., & Shelton, R

    Petre, R., Kuntz, K. D., & Shelton, R. L. 2002, ApJ, 579, 404

    work page 2002

  46. [46]

    G., Slane, P

    Posselt, B., Pavlov, G. G., Slane, P. O., et al. 2017, ApJ, 835, 66

    work page 2017

  47. [47]

    & Leahy, D

    Ranasinghe, S. & Leahy, D. A. 2018, AJ, 155, 204

    work page 2018

  48. [48]

    Rees, M. J. & Gunn, J. E. 1974, MNRAS, 167, 1

    work page 1974

  49. [49]

    M., & Hester, J

    Rho, J., Petre, R., Schlegel, E. M., & Hester, J. J. 1994, ApJ, 430, 757

    work page 1994

  50. [50]

    Ruderman, M. A. & Sutherland, P. G. 1975, ApJ, 196, 51

    work page 1975

  51. [51]

    B., Bodaghee, A., et al

    Safi-Harb, S., Burdge, K. B., Bodaghee, A., et al. 2023, arXiv e-prints, arXiv:2311.07673

    work page arXiv 2023

  52. [52]

    Safi-Harb, S., Ogelman, H., & Finley, J. P. 1995, ApJ, 439, 722

    work page 1995

  53. [53]

    2004, AJ, 127, 1098

    Seta, M., Hasegawa, T., Sakamoto, S., et al. 2004, AJ, 127, 1098

    work page 2004

  54. [54]

    L., Kuntz, K

    Shelton, R. L., Kuntz, K. D., & Petre, R. 2004, ApJ, 611, 906

    work page 2004

  55. [55]

    R., Watson, M

    Smith, A., Jones, L. R., Watson, M. G., et al. 1985, MNRAS, 217, 99 Strüder, L., Briel, U., Dennerl, K., et al. 2001, A&A, 365, L18

    work page 1985

  56. [56]

    Sturrock, P. A. 1971, ApJ, 164, 529

    work page 1971

  57. [57]

    2009, ApJ, 691, 895

    Swaluw, E. 2009, ApJ, 691, 895

    work page 2009

  58. [58]

    2015, ApJ, 808, 100

    Temim, T., Slane, P., Kolb, C., et al. 2015, ApJ, 808, 100

    work page 2015

  59. [59]

    J., Bertsch, D

    Thompson, D. J., Bertsch, D. L., Dingus, B. L., et al. 1996, ApJS, 107, 227

    work page 1996

  60. [60]

    Turner, M. J. L., Abbey, A., Arnaud, M., et al. 2001, A&A, 365, L27

    work page 2001

  61. [61]

    2012, PASJ, 64, 141

    Uchida, H., Koyama, K., Yamaguchi, H., et al. 2012, PASJ, 64, 141

    work page 2012

  62. [62]

    2012, ApJ, 749, L35 van der Swaluw, E., Downes, T

    Uchiyama, Y., Funk, S., Katagiri, H., et al. 2012, ApJ, 749, L35 van der Swaluw, E., Downes, T. P., & Keegan, R. 2004, A&A, 420, 937

    work page 2012

  63. [63]

    Wang, Q. D. 2021, Research Notes of the American Astronomical Society, 5, 5

    work page 2021

  64. [64]

    D., Lu, F., & Lang, C

    Wang, Q. D., Lu, F., & Lang, C. C. 2002, ApJ, 581, 1148

    work page 2002

  65. [65]

    G., Willingale, R., Pye, J

    Watson, M. G., Willingale, R., Pye, J. P., et al. 1983, in Supernova Remnants and their X-ray Emission, ed. J. Danziger & P. Goren- stein, Vol. 101, 273–280

    work page 1983

  66. [66]

    2000, ApJ, 542, 914

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

    work page 2000

  67. [67]

    M., & Dewey, R

    Wolszczan, A., Cordes, J. M., & Dewey, R. J. 1991, ApJ, 372, L99

    work page 1991

  68. [68]

    Wootten, H. A. 1977, ApJ, 216, 440 Article number, page 13 of 13

    work page 1977