Pulsar Glitches: A Review
Round 1
Reviewer 1 Report
REFEREE REPORT
to the paper of Zhou et al. Pulsar Glitches: A Review
The paper contains a detailed review of pulsar glitches, including observational methods of their discovery, observational properties and classification of all known glitches. Some theoretical models of their origin are described, explaining the glitch event, and different frequency behavior after the glitch, when superfluidity plays a very important role. Anti- glitches observed in some SGR are mentioned, and it is rightly stressed that “anti-glitches are strongly challenging the standard glitch theories.”
In the description of the pulsar glitch models the longest part is devoted to Superfluid Vortex Dynamics model (pages 11-18). Mainly it contains explanation of the timing behavior after the glitch, but I was not able to find the explanation of the rapid increase (jump) of the observed frequency inside this glitch model.
In the Crustquake Model (Pages 19-23) this jump can be explained, while the post-glitch behavior is connected with superfluid vortexes, like in the previous model.
I would like to attract the intention of the authors to the glitch model, connected with neutronization in the outer crust, leading to pressure deficit and its contraction, which rate may increase considerably because of properties of odd-even nuclei, see:
----------------------------------------------------------------
Bisnovatyi-Kogan, G. S.
A pulsar as a neutron star and weak interactions.
Radiophysics and Quantum Electronics, Volume 13, Issue 12, pp.1441-1444 (1970).
-------------------------------------------------------------------
The authors indicate in the first section (page 1) that “millisecond pulsars
(MSPs) have the greatest long-term stability of period. The MSP PSR J0437–4715 is considerably more stable than standard atomic clocks”
In this connection I would like to remind, that binary millisecond pulsars, as the most powerful physical laboratory, and some applications, had been discussed in the publications [I-IV] below, before the mentioned references [357-360].
------------------------------------------------------------------------------------------------
I.
G. S. Bisnovatyi-Kogan
BINARY RECYCLED PULSARS AS THE MOST PRECISE PHYSICAL
LABORATORY
Journal of Physical Studies, vol. 11, Issue 4, p.450-456 (2007)
arXiv:0801.4738
II.
Bisnovatyi-Kogan, G.
Recycled binary pulsars: The best laboratory for fundamental physics
Conf. Proc. No.93 “Frontier Objects in Astrophysics and Particle Physics”, Vulcano Workshop, held May 22-27, 2006 in Vulcano, Italy. Edited by F. Giovannelli and G. Mannocchi., p.223, SIF, Bologna, 2007
III.
Bisnovatyi-Kogan, G. S.
Recycled binary pulsars - a most precise laboratory of fundamental physics
Astronomical and Astrophysical Transactions, vol. 25, Issue 5, p.369-377 (2006)
IV.
G. Bisnovatyi-Kogan
Binary recycled pulsars: a powerful physical laboratory
Mem. S.A.It. Vol. 81, P. 258 (2010)
----------------------------------------------------------------------------------------------------
The review contains a lot of information, with 354 references, occupying half of the length of the paper.
After explanation of the jump in the Superfluid Vortex Dynamics model, and including the above mentioned
references:
1. Bisnovatyi-Kogan, G. S.
A pulsar as a neutron star and weak interactions.
Radiophysics and Quantum Electronics, Volume 13, Issue 12, pp.1441-1444 (1970).
and
2. G. Bisnovatyi-Kogan
Binary recycled pulsars: a powerful physical laboratory.
Memorie della Societa Astronomica Italiana, Vol. 81, P. 258-267 (2010)
(see also arXiv:0801.4738).
it may be published in the “Universe”.
Author Response
Dear Editor and Reviewers,
Please see the attachment. We cannot upload our revised manuscripts. This seems inconvenient for reviewers to view our revised content.
Best wishes,
Authors
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript `Pulsar Glitches: A Review' is written by well known experts in pulsar glitches, so it comes with no surprise that it is indeed a very extensive and timely review, which includes observational, theoretical, and statistical aspects. The manuscript is generally well-written and organized. I recommend it for publication in Universe with no doubts.
However, I would like to draw the author’s attention to some, mostly optional, comments and misprints:
1. The reference list is included two times and started from Ref. [356]
2. Line 65: the equation number is not specified (“given by equation (??)”)
3. Line 105: the acronym HMM is introduced before it is specified
4. Tables 1 and 2, Eq. (9) are not fitted to the page width
5. Line 154: It can be worth to introduce term ‘timing noise’, probably near Eq. (1) or (2)
6. Line 168: That are ‘first-class pulsars’?
7. Line 176: Please clarify ` eventually becomes linear recovery in time’
8. Line 195: ` then continues to rise linearly’ means that \dot nu agrees with Eq. (1)?
9. Fig. 4: It would be great to add a line (or region), corresponding to the exponential fit. The numerical ‘mean post-glitch value has’ can be also quoted.
10. Lines 228-230: Is the spin frequency really increasing for slow glitches or it is increasing only in comparison with preglitch parameters of the Eq.(1)? According to Fig. 5, \dot nu seems to be negative for whole shown timespan
11. Line 290-291:` Until now, only unusual class of pulsars have been observed to undergo anti-glitches.’ Does it means that pulsars with anti-glitches have some specific features except anti-glitches or the meaning is that there are just a few pulsars with observed anti-glitches?
12. Lines 364-365: direct Urca process is not introduced. Probably, it can be worth to discuss why decay timescales for magnetars implies that direct Urca may operate inside them
13. Lines 373-374: Statement ‘The observations of a handful of pulsars confirm this prediction’ seems to be too strong or misleading: there are other (not related to the glitches) models, which can describe late time heating (see, e.g., Ref. [539] for review)
14. Line 457: At the subsequent publications [Kobyakov&Pethick, PhRvC, 94 (2016), 055806] authors of Ref. [596] explicitly write that destabilization of the lattice is unlikely (see the end of the second paragraph at Sec. 5 there).
15. Lines 460-461: It seems reasonable to define term `pasta phases’
16. Lines 493-494: I don’t agree that Refs. [631-633] agrees with Ref. [630] - they don’t predict \theta_cr to be \propto Z.
17. Line 489: more accurate value of \mu can be quoted [e.g. from the first line of Table 1 at Ogata&Ichimaru, Phys. Rev. A 42 (1990)]
18. Line 521:` Baym % Pines’ -> `Baym & Pines’
19. Line 641: References to [Morales&Horowitz arXiv:2209.03222] and [Gittins& Andersson MNRAS, 507 (2021), 116] can be added in addition to Ref. [641]
20. After Eq. (58): Check dimension for Phi_o
21. Eq. (62): 10^15 is doubled in denominator (two times!)
22. Before Eq. (63): Please clarify that means `a permanent offset in the perpendicular dipolar’ (offset with respect to that?)
23. Figure 9: It can be worth to add a legend to the figure (figure is described at the caption, but legend is useful at any case). The blue line (number of glitching pulsars) seems to be nonmonotonic and decrease at some time intervals. That is the reason of this decrease?
24. Line 675: to avoid confusions, it can be worth to specify that negative values of \Delta \dot \nu correspond to more rapid spindown. At the next line an absolute value of \Delta \dot \nu should be discussed (larger glitches have large absolute value of \Delta \dot \nu).
25. Lines 678-679: Please clarify or reformulate `For most pulsars glitches take place at irregular intervals with random distribution of magnitudes’. According to the next statement Vela pulsars has a Gaussian distribution of repetition times (thus they are also random).
26. Probably, it can be worth to discuss the accumulated effect of the glitches in more details [with impressive plots of linear accumulation, as it is done e.g. by Andresson et al, Phys. Rev. L, 109 (2012), 241103], however, it is clearly up to the authors decision.
27. Line 29: The very first passage of the paper (`Pulsars are so named because they continuously emit radio emission…’) looks rather confusing
28. Line 54: term ‘light cylinder’ is undefined
29. Line 56: Statement that ‘There is a stull a lack of the reliable observational evidence and theoretical models to accurately describe the spin evolution of pulsars’ is rather confusing: as discussed in the manuscript, there are a large amount of observations which allow precise description of spin evolution
30. Eq. (1): the phase of pulse sequence is described by Eq. (1) after removing of the Earth motion effect as well as possible orbital motion of the pulsar. I believe, it is worth to mention.
31. It can be worth to quote very recent paper Younes et al. [arXiv:2210.11518], which indicates possible relation of magnetar glitches and FRBs, however it is up to the authors decision.
Author Response
Dear Editor and Reviewers,
Please see the attachment. We cannot upload our revised manuscripts. This seems inconvenient for reviewers to view our revised content.
Best wishes,
Authors
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The review is covering most problems related to pulsar glitches.
Author Response
Dear Editor and Reviewers,
We don't reply because the reviewer didn't leave any new comments. Thank you!
Sincerely,
Authors
Reviewer 2 Report
Authors reply for vast majority of my comments and add some extra changes/updates to the paper. I believe that the paper is sufficiently improved to recommend it for publication in Universe.
I have just a few minor comments:
1) A dot should be removed from the dimension of Phi_0 after Eq. (58) (it should be 'G cm^2', not 'G.cm^2')
2) The shear modulus, as it is calculated in Refs. [287–290], differs from the the order of magnitude estimate provided by authors for a factor of 5, thus statement (few lines after Eq. 51): 'Recent theoretical and computational calculations show that the more accurate shear modulus value for rigid neutron star crust does not differ significantly from the above quoted order of magnitude estimate' seems to be rather misleading.
Author Response
Dear Editor and Reviewers,Please see the attachment. Thank you very much!
Sincerely,Authors
Author Response File: Author Response.pdf
