Pith. Sign in

REVIEW

A statistical study of 233 pulsar proper motions

PaperPDF from arXiv

data files

ReviewThe objections and verdict, as JSON Paper breakdownThe authors' claims, conditions and measurements, as JSON Signed receiptProof this review has not been altered
X Bluesky LinkedIn Reddit Hacker News
G. Hobbs, D. R. Lorimer, A. G. Lyne, M. Kramer

Astrophysics · Submitted 26 Apr 2005 · 77 references

Pith's verdict: The catalogue and the ~400 km/s mean will hold up; the Maxwellian shape, the no-bimodality claim and the 35% escape fraction are softer than the abstract implies.

T0 · AI review

How this review was made: An AI referee (selfhosted/deepseek-v4.1-flash) read the paper on October 29, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

  1. T0 AI review An AI read the paper and answered a fixed list of questions.
  2. T1 Audit Automatic checks that the references and files the paper relies on exist and match.
  3. T2 Compute The paper's code or calculations re-run with the same results.
  4. T3 Formal statement The claims written out in a formal math language a computer can read.
  5. T4 Proof Those claims proved, and the proof checked by computer.

How Pith checks papers →

· 5 major objections · 10 minor · Ask about this paper · The compiled record · Read the full review →
Challenge this review Comment (0) Read on arXiv ↗
Cite ▾
arXiv IDastro-ph/0504584 (version 1)
Pith IDXBBACYWJ, Pith's permanent record of this paper and its review
CitationA. G. Lyne, D. R. Lorimer, G. Hobbs, M. Kramer. "A statistical study of 233 pulsar proper motions." arXiv:astro-ph/0504584 (2005). https://pith.science/paper/XBBACYWJ
Cite this reviewBibTeX for Pith's review of this paper
Claim paper

Why Pith says this

Highlight any text to comment on it.

Referee report

How Pith checks papers → · Full audit of this paper →

The paper

The paper claims

From 233 measured pulsar proper motions, the paper argues that young neutron stars are born with a mean three-dimensional speed of 400 km/s, drawn from a single Maxwellian distribution rather than two distinct velocity groups.

The reading

Pulsars are neutron stars, and they move fast — much faster than the massive stars they descend from. The paper assembles the largest catalogue to date of measured pulsar proper motions (233 objects, most from radio timing and interferometry) and turns those angular motions into speeds using a Galactic electron-density model to convert dispersion measures into distances. The central move is a deconvolution: because we see pulsar velocities projected onto the sky, the observed one- and two-dimensional speed distributions are blurred versions of the true three-dimensional one, and the authors invert that blurring for the 73 pulsars younger than 3 Myr. The recovered birth-speed distribution has a mean of $400(40)$ km s$^{-1}$ and is well fit by a Maxwellian with one-dimensional rms $265$ km s$^{-1}$, with no sign of the second, fast component that some earlier analyses had favoured. If right, this pins down the input distribution used in pulsar population synthesis, sets what fraction of neutron stars escape the Galaxy, and constrains which asymmetric supernova kick mechanisms are viable.

What carries the argument

The load-bearing device is a deconvolution of the projection kernels. For a fixed space velocity $V_3$, an isotropic distribution produces $1$-D speeds with probability density $P(V_1) = V_1/V_3$ and $2$-D speeds with $P(V_2) = V_2^2/(V_3 (V_3^2 - V_2^2)^{1/2})$ on $0 < V_1, V_2 < V_3$. These act as known blurring functions, so the observed histograms of $V_1$ and $V_2$ can be cleaned iteratively — a CLEAN-type algorithm that repeatedly cross-correlates the kernel with the residual distribution, subtracts a scaled copy, and records the velocity of each subtraction — to yield the underlying $V_3$ histogram. The authors validate the procedure on simulated unimodal and bimodal parent distributions and recover both forms correctly, which is what licenses the negative claim about bimodality.

Extended reading notes

Core claim

The paper's claim is that the three-dimensional birth velocity distribution of ordinary (non-recycled) pulsars can be recovered from projected speeds, and that when it is recovered it is single-peaked and broad: mean $400(40)$ km s$^{-1}$, Maxwellian with $1$-D rms $265$ km s$^{-1}$. Supporting results include mean 2-D speeds of $246(22)$ km s$^{-1}$ for normal pulsars and $87(13)$ km s$^{-1}$ for recycled ones, a ratio of mean 2-D to mean 1-D speed of $1.6(2)$ against the $1.57$ expected for an isotropic velocity vector, and two objects (PSRs B2011+38 and B2224+65) near $1600$ km s$^{-1}$ whose gap from the rest of the sample the authors argue is small-number sampling of a long tail rather than a separate population. The paper also reports that pulsars found inside supernova remnants move more slowly than young pulsars generally, which the authors attribute to fast objects leaving the remnant shell quickly.

Load-bearing premise

Every speed is a proper motion multiplied by a distance, and nearly all those distances come from one electron-density model; if that model is systematically off for the young pulsars in the deconvolution sample, the recovered 400 km/s mean moves with it, a caveat the authors state themselves in their distance section.

Editorial extensions

If this is right

  • Pulsar population synthesis and Galactic neutron-star birthrate models can replace a free velocity distribution with a specific Maxwellian, $\sigma = 265$ km s$^{-1}$.
  • With a Galactic escape velocity near $430$ km s$^{-1}$, about 35 per cent of pulsars should escape the Galactic potential, a number that shifts to 50 per cent or 16 per cent under the competing distributions the paper rejects.
  • Kick mechanisms confined to low speeds — local convective instabilities, which the paper says cap out near $100$ km s$^{-1}$ — cannot be the dominant channel.
  • The two extreme objects near $1600$ km s$^{-1}$ should be checked by independent distance measurements; the bow shock already seen for PSR B2224+65 supports a speed above $800$ km s$^{-1}$.
  • Proper motions for PSRs B1830$-$08 and B2334+61 are consistent with birth inside the remnants W41 and G114.3+0.3, so those associations survive the new data.

Reading between the lines

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

  • The 450-to-400 km s$^{-1}$ downward revision is almost entirely a distance-model effect, not a proper-motion effect; a future electron-density model that pushes distances back up would move the mean back toward the earlier value without any new astrometry.
  • Because the deconvolution assumes a single isotropic speed for each pulsar, a real correlation between kick direction and spin axis would not bias the mean speed but could bias the shape near the peak, which is where the Maxwellian fit is currently tightest.
  • The escape-fraction figure is a clean, checkable prediction: a census of hypervelocity neutron stars leaving the Galaxy, or of the neutron-star mass budget in the Galactic halo, would test the 35 per cent number independently of any distance model.
  • The recycled-pulsar mean of $87(13)$ km s$^{-1}$ is consistent with the idea that a second supernova or a long accretion phase damps the kick, but the sample is still small enough that a handful of new millisecond-pulsar parallaxes would sharpen or break that reading.
Original abstract

We present and analyse a catalogue of 233 pulsars with proper motion measurements. The sample contains a wide variety of pulsars including recycled objects and those associated with globular clusters or supernova remnants. After taking the most precise proper motions for those pulsars for which multiple measurements are available, the majority of the proper motions (58%) are derived from pulsar timing methods, 41% using interferometers and the remaining 1% using optical telescopes. Many of the 1-D and 2-D speeds (referring to speeds measured in one coordinate only and the magnitudes of the transverse velocities respectively) derived from these measurements are somewhat lower than earlier estimates because of the use of the most recent electron density model in determining pulsar distances. The mean 1-D speeds for the normal and recycled pulsars are 152(10) and 54(6) km/s respectively. The corresponding mean 2-D speeds are 246(22) and 87(13) km/s. PSRs B2011+38 and B2224+64 have the highest inferred 2-D speeds of ~1600 km/s. We study the mean speeds for different subsamples and find that, in general, they agree with previous results. Applying a novel deconvolution technique to the sample of 73 pulsars with characteristic ages less than 3 Myr, we find the mean 3-D pulsar birth velocity to be 400(40) km/s. The distribution of velocities is well described by a Maxwellian distribution with 1-D rms sigma=265 km/s. There is no evidence for a bimodal velocity distribution. The proper motions for PSRs B1830-08 and B2334+61 are consistent with their proposed associations with the supernova remnants W41 and G114.3+0.3 respectively.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 9,085 input tokens.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.45 · human participants 0.01 · controlled comparison 0.10 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.96 · mentions code or data availability 0.03.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; .

We present and analyse a catalogue of 233 pulsars with proper motion measurements. The sample contains a wide variety of pulsars including recycled objects and those associated with globular clusters or supernova remnants. After taking the most precise proper motions for those pulsars for which multiple measurements are available, the majority of the proper motions (58%) are derived from pulsar timing methods, 41% using interferometers and the remaining 1% using optical telescopes. Many of the 1-D and 2-D speeds (referring to speeds measured in one coordinate only and the magnitudes of the transverse velocities respectively) derived from these measurements are somewhat lower than earlier estimates because of the use of the most recent electron density model in determining pulsar distances. The mean 1-D speeds for the normal and recycled pulsars are 152(10) and 54(6) km/s respectively. The corresponding mean 2-D speeds are 246(22) and 87(13) km/s. PSRs B2011+38 and B2224+64 have the highest inferred 2-D speeds of ~1600 km/s. We study the mean speeds for different subsamples and find that, in general, they agree with previous results. Applying a novel deconvolution technique to the sample of 73 pulsars with characteristic ages less than 3 Myr, we find the mean 3-D pulsar birth velocity to be 400(40) km/s. The distribution of velocities is well described by a Maxwellian distribution with 1-D rms sigma=265 km/s. There is no evidence for a bimodal velocity distribution. The proper motions for PSRs B1830-08 and B2334+61 are consistent with their proposed associations with the supernova remnants W41 and G114.3+0.3 respectively.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 We present and analyse a catalogue of 233 pulsars with proper motion measurements. contribution 1.00 0.95 0.04 asserted 1.00
s1 The sample contains a wide variety of pulsars including recycled objects and those associated with globular clusters or supernova remnants. contribution 0.80 0.42 0.03 asserted 1.00
s2 After taking the most precise proper motions for those pulsars for which multiple measurements are available, the majority of the proper motions (58%) are derived from pulsar timing methods, 41% using interferometers and the remaining 1% using optical telescopes. method 0.92 0.80 0.04 asserted 1.00
s3 Many of the 1-D and 2-D speeds (referring to speeds measured in one coordinate only and the magnitudes of the transverse velocities respectively) derived from these measurements are somewhat lower than earlier estimates because of the use of the most recent electron density model in determining pulsar distances. result 0.89 0.85 0.04 asserted 0.95
s4 The mean 1-D speeds for the normal and recycled pulsars are 152(10) and 54(6) km/s respectively. result 1.00 0.93 0.09 asserted 1.00
s5 The corresponding mean 2-D speeds are 246(22) and 87(13) km/s. result 1.00 0.92 0.06 asserted 1.00
s6 PSRs B2011+38 and B2224+64 have the highest inferred 2-D speeds of ~1600 km/s. result 1.00 0.87 0.06 asserted 1.00
s7 We study the mean speeds for different subsamples and find that, in general, they agree with previous results. result 0.85 0.92 0.09 asserted 0.97
s8 Applying a novel deconvolution technique to the sample of 73 pulsars with characteristic ages less than 3 Myr, we find the mean 3-D pulsar birth velocity to be 400(40) km/s. result 0.87 0.98 0.29 asserted 1.00
s9 The distribution of velocities is well described by a Maxwellian distribution with 1-D rms sigma=265 km/s. result 0.98 0.92 0.20 asserted 1.00
s10 There is no evidence for a bimodal velocity distribution. result 0.90 0.87 0.18 asserted 0.98
s11 The proper motions for PSRs B1830-08 and B2334+61 are consistent with their proposed associations with the supernova remnants W41 and G114.3+0.3 respectively. result 0.87 0.80 0.04 hedged possibility 0.97

What kind of paper the classifier reports this is: dataset or benchmark 0.73 · evidence from analysis of existing data 0.93.

What was examined, and what was not

sources read
  • arXiv listing abstract v1
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. The Galactic motions of the pulsars in our sample. A pulsar is currently at the position indicated by a circle and the track indicates its motion for the last 1 Myr assuming no radial velocity. uncertainty less than 15 mas yr−1 in at least one coordinate. For 87 of these pulsars, these provide more precise proper motions than the earlier measurements. Direct distance measurements have only been obtained for a small number of pulsars. The majority of distances are estimated from the dispersion measure and a Galactic electron density model. Using the Taylor & Cordes (1993; hereafter…
Figure 2. Comparison between pulsar 2-D speeds obtained using the CL02 model with: (a) the TC93 model; (b) the Lyne, Manchester & Taylor (1985) model. sars at distances almost halfway between the Lyne, Manch￾ester & Taylor (1985) model (that was commonly used prior to the TC93 model) and the TC93 model (Figure 2b). For the remainder of this paper we use the CL02 model (un￾less independent distance estimates exist), but caution that, even with this most recent distance model, the distances to some pulsars, and hence their velocities, may be significantly under- or over-estimated. We therefore…
Figure 3. One dimensional speeds for pulsars in our sample that: a) have characteristic ages greater than 3 Myr; (b) have charac￾teristic ages less than 3 Myr. c 0000 RAS, MNRAS 000, 000–000
Figure 4. Two-dimensional speeds for: (a) all the pulsars in our sample; (b) pulsars with characteristic ages less than 3 Myr; (c) recycled pulsars; (d) normal (not recycled) pulsars with characteristic ages greater than 3 Myr. The mean 2-D speeds for each sample are 211(18), 307(47), 87(13) and 209(19) km s−1 respectively. Panels b, c and d are drawn to the same scale. c 0000 RAS, MNRAS 000, 000–000
Figure 5. 2-D velocity versus orbital period for binary millisec￾ond pulsars. we obtain for the solitary and binary millisecond pulsars are 77(16) and 89(15) km s−1 respectively which are not signifi￾cantly different. Tauris & Bailes (1996) predicted that the velocities of binary millisecond pulsars should increase with decreasing orbital period. No such correlation was found in their data which they attributed to selection effects. Our data, shown in
Figure 6. The motion of pulsars with respect to the Galactic plane. Pulsars indicated by a circle have τc < 1 Myr, those with τc > 1 Gyr by a ‘*’ symbol. All other pulsars are indicated using an ‘x’. for a few pulsars change significantly. For instance, in the most extreme case the velocity of PSR B1933+16 reduces from 346 to 208 km s−1 . 6 THREE-DIMENSIONAL VELOCITIES OF YOUNG PULSARS With the exception of two binary pulsars (Bell et al. 1995; van Kerkwijk et al. 1996) it is generally not possible to make a direct measurement of the true 3-D space velocity of a pulsar. However, as the obs
Figure 7. The 3-D velocity distributions obtained from the observed 1-D (left) 2-D (right) distributions using the deconvolution technique described in the text. The uncertainties on each histogram bin are calculated as √ N where N is the number of pulsars in each bin. The histograms are normalised to unit area. The dotted curve shows the 3-D distribution favoured by Arzoumanian et al. (2002). The solid curve is the best-fitting Maxwellian distribution to the histogram from the 2-D distribution with σ = 265 km s−1 . D distribution with the 1-D and 2-D probability density functions. We…

Figures reproduced from arXiv:astro-ph/0504584 by the authors.

References
How later papers used it

448 later papers cite it

Evidence: substantial. 435 of the citing papers share no author with it, and 213 of those carry a confident label from Pith's citation classifier.

Pith read 40 of the 733 citing sentences, choosing only those whose citation markers point at this paper alone, and wrote the paraphrases from them. The summary, the counts, the evidence level, the links and the quotes come from code; the summary counts the papers listed below. A later paper is listed under a label when Pith's citation classifier gives one of its sentences that label at probability 0.8 or more (0.95 for support), Pith's reading finds that the citing paper itself did it, and a second check confirms the paraphrase against the sentence. This section lists uses only. It does not list criticism or disagreement, so their absence here says nothing about how the paper has been received. Papers that share an author with this one are listed apart, under "By the same authors". A quote is the citing authors' own sentence, shown when their paper's licence is CC BY, CC BY-SA or CC0. JSON

Uses its method or tool 2 of 35 papers with this label
Uses its data or values 10 of 153 papers with this label
Cites it as support 1 of 9 papers with this label
How the literature uses it

73 arXiv papers cite this in 95 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 53 sentences without a confident label

Contests it 3 papers
Uses its method or tool 4 papers
Uses its data or values 31 papers
Compares with it 1 paper
Cites it as background 3 papers

Discussion

Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.