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Late-Time Behavior of Stellar Collapse and Explosions: II. Nonlinear Evolution

General Relativity and Quantum Cosmology · Submitted 10 Jul 1993 · 11 references

Pith's verdict: The physics holds up; the corrupted abstract is an arXiv artifact, not the authors' text, and the classifier record built on it should be ignored.

T0 · AI review

How this review was made: An AI referee (selfhosted/deepseek-v4.1-flash) read the paper on November 13, 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.

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arXiv IDgr-qc/9307010 (version 2)
Pith IDFAY3BMYI, Pith's permanent record of this paper and its review
CitationCarsten Gundlach, Richard Price adn Jorge Pullin. "Late-Time Behavior of Stellar Collapse and Explosions: II. Nonlinear Evolution." arXiv:gr-qc/9307010 (1993). https://pith.science/paper/FAY3BMYI
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Referee report
The paper

The paper claims

The late-time fingerprints of a black hole survive a fully nonlinear collapse simulation, and one of them appears even when no black hole forms.

The reading

Linear perturbation theory makes two sharp predictions about the late stages of collapse: a disturbed black hole should ring at fixed complex frequencies set by its mass, and the radiation should eventually die away as a power of time — a 'tail' — rather than exponentially. This paper asks whether those two features are real properties of gravitational collapse or artifacts of the fixed-background approximation that produced them. The authors evolve a spherically symmetric, self-gravitating massless scalar field with a fully nonlinear characteristic code, then evolve a second, non-backreacting test scalar on the resulting dynamic spacetimes and split it into multipoles. They report both features with exponents and frequencies close to the linear predictions, and, more pointedly, they report the tails in initial data too weak to form a horizon, where no ringing appears at all. One note on the deposited record: the abstract field attached to this manuscript contains only a remark about a broken figure encoder, not the scientific abstract, which appears at the head of the manuscript body and is what this summary follows.

What carries the argument

The engine is a characteristic (null) grid: retarded time $u$ labels outgoing light cones, $v$ labels ingoing null geodesics, and the areal radius $r(u,v)$ is itself an evolved metric function rather than a coordinate. The scalar is repackaged through an auxiliary field $psi$ with $varphi = (1/r)int_0^r psi,dr$, so that the wave equation becomes a transport equation along ingoing characteristics, $(partial_u - (bar g/2)partial_r)psi = (g-bar g)(psi-varphi)/(2r)$, while $varphi$ is recovered by radial integration along each outgoing cone. The metric functions come from quadratures, $g = exp[4pi int_0^r (partial_r varphi)^2 r,dr]$ and $bar g = (1/r)int_0^r g,dr$, so spherical symmetry removes any independent gravitational degree of freedom. Each step is a second-order Runge-Kutta update in $u$ with trapezoidal radial integrals, and the step size is chosen so that no grid point moves further in $r$ than its neighbour's spacing. The multipole test field adds a centrifugal term, $(l(l+1)/2),g,varphi_{ml}$, to the same transport equation, which is what makes the $l$-dependence of the tails and the weakly damped high-$l$ ringing accessible. The authors are candid that the code is better than first order but not second order, and that the dominant error source is the linear interpolation used to impose the $r=0$ boundary condition, which they compensate for by refining the radial grid by a factor of 16 near the origin.

Extended reading notes

Core claim

The paper's claim is that the late-time behaviour predicted by linear perturbation theory of Schwarzschild spacetime — quasinormal ringing and power-law tails — is reproduced by a full nonlinear integration of the Einstein equations coupled to a spherically symmetric scalar field, in regimes where nonlinearities genuinely matter. Measured tail exponents are close to the linear predictions: $-2.74$, $-2.63$, $-2.63$ and $-2.68$ for four Gaussian amplitudes against a predicted $-3$, and $-2.08$, $-1.98$, $-1.95$ and $-1.86$ for four static-static amplitudes against a predicted $-2$. For the test field, the least-damped ringing frequencies are matched tightly: a measured half-period of $1.811$ against a predicted $1.819$ for $l=1$ (within $0.7$ percent) and $1.105$ against $1.104$ for $l=2$ (within $0.2$ percent). The sharper half of the claim is that tails develop with the same exponents whether or not a horizon forms, and that ringing appears abruptly at the threshold of collapse for Gaussian data but fades gradually for static-static data. The authors read this as evidence that tails come from backscattering at large radius, which does not care about the small-$r$ geometry, while ringing requires a compact object and does.

Load-bearing premise

The argument assumes that predictions derived on a fixed Schwarzschild background transfer to a time-dependent, mass-losing background with some retarded-time average playing the role of $M$, and the authors say outright that it is unclear which mass to use — which is why exponent comparisons succeed while the predicted tail amplitude comes out roughly an order of magnitude too large.

Editorial extensions

If this is right

  • Once a horizon has settled down, the late-time gravitational waveform of a strongly nonlinear collapse can be modelled by linear perturbation theory, so ringdown templates do not require a full nonlinear simulation for every source.
  • Power-law tails should be expected in the late signal of any roughly spherical, asymptotically flat radiating spacetime, including bursts that leave no remnant behind.
  • The abrupt onset of ringing at the black-hole threshold, set against the smooth continuity of the tail, gives a qualitative discriminator between 'a horizon formed' and 'it very nearly did'.
  • The multipole dependence of the tail, $t^{-(2\ell+3)}$ for generic data and $t^{-(2\ell+2)}$ for initially static multipoles, survives on a time-dependent background, so the slope of a late-time signal identifies which multipole is dominating it.
  • Tail amplitude scales as the cube of the initial data amplitude while the Bondi mass scales as the square, which is what one expects if the tail is radiation scattered once off the spacetime curvature, picking up a single factor of mass.

Reading between the lines

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

  • If large-radius backscatter really is the mechanism, the tail should weaken or vanish when the numerical domain is truncated well inside the scattering region; that is a cheap test the authors did not run and would sharpen the causal story considerably.
  • The order-of-magnitude shortfall in tail amplitude relative to the linear prediction may be an artifact of the first-order treatment at $r=0$ that the authors themselves name as their main error source; a code with a properly regular centre condition would separate the physics from the numerics.
  • Because the tail crosses the collapse threshold continuously while the ringing does not, the tail amplitude could in principle serve as a mass calibration for a near-critical remnant, since it tracks radiated energy rather than horizon formation.
  • The test-field equations deliberately omit the backreaction a genuine perturbation of the background scalar would produce, so the agreement reported here is a best case; the disagreement case, where the perturbation is coupled to the geometry, is left untested.
Original abstract

Problem with the figures should be corrected. Apparently a broken uuencoder was the cause.

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-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 2,141 input tokens, $0.0001 reported.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.49 · human participants 0.03 · controlled comparison 0.03 · randomized assignment 0.01 · states quantitative result 0.03 · compares with prior results 0.06 · mentions code or data availability 0.04.

The abstract, sentence by sentence

arXiv listing abstract v2. Results and the main claim are underlined; .

Problem with the figures should be corrected. Apparently a broken uuencoder was the cause.

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 Problem with the figures should be corrected. limitation 0.66 0.14 0.02 asserted 0.96
s1 Apparently a broken uuencoder was the cause. background 0.49 0.28 0.02 hedged possibility 0.54

What kind of paper the classifier reports this is: position or commentary 0.61 · evidence from simulation or computation 0.66.

What was examined, and what was not

sources read
  • arXiv listing abstract v2
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 conformal diagram of the spherical collapse spacetime fo
Figure 2. Our null grid in coordinates t(u, r) and r. The u = const. (tB = const.) grid lines approach the event horizon in a finite interval of u which is an infinite interval of tB
Figure 4. The convergence of φ(r, tB = 50) with decreasing grid size. The axes and the initial data are the same as for
Figure 5. Part of a plot of φ(r = 10) versus tB, in a region where φ is dominated by QN ringing. From bottom to top are shown runs with initial radial grid sizes 1/20, 1/40, 1/80, 1/160 and 1/320. Initial data is the same as in
Figure 7. Log-log plots of φ(r = 10, tB) for Gaussian data with different amplitudes. Each plot starts after the last change of sign of φ. The amplitudes of the initial Gaussian are a) 0.06, b) 0.034 (marginally collapsing), c) 0.033 (marginally noncollapsing), d) 0.01. The power law nature of all curves is clearly visible; the exponents are a) −2.74, b) −2.63, c) −2.63, d) −2.68, compared to a linearized theory prediction of −3. Only the two collapsing cases, show QN ringing
Figure 8. A closeup on φ(r = 10, tB) in the region of QN ringing for initial Gaussian data. Solid line: Amplitude 0.034, which collapses marginally, showing QN ringing (the small feature around t ≈ 5). Dotted line: Amplitude 0.033, which marginally does not collapse. Note the complete absence of QN ringing
Figure 9. A closeup of φ(r = 10, tB) in the region of QN ringing, for static-static data a) Amplitude 0.50, which collapses, and here shows QN ringing. b) Amplitude 0.35, showing only faint QN ringing. c) Amplitude 0.29, which marginally collapses. d) Amplitude 0.28 which marginally does not collapse. There is no qualitative difference between c) and d), in contrast to the case of Gaussian data depicted in
Figure 11. Test fields ϕ m l (r = 10, tB) on a Gaussian background, amplitude 0.06. The three graphs are l = 0, l = 1, l = 2 (in order of increasing frequency)
Figure 13. Log-log plots of test fields ϕ m l (r = 10, tB) for different multipole indices l on one background spacetime. The background is evolved from static-static data for φ with amplitude 0.1 (noncollapsing). The initial data for the test field is in each case a Gaussian (the test field amplitude, 1.0, has no significance). From top to bottom l = 0, then l = 1, l = 2 and l = 3. The best fit for the power laws exponents are −2.70, −3.66, −5.52, −7.26, compared to predictions of −3, −5, −7 and −9. 22
Figure 14. initial Bondi mass amplitude of tail
Figure 15. Mass of black hole formed versus difference between the am

Showing 11 of the paper's 15 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:gr-qc/9307010 by the authors.

References
How the literature uses it

35 arXiv papers cite this in 39 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 · 14 sentences without a confident label

Uses its method or tool 14 papers
Compares with it 1 paper
  • This behaviour is in contrast to that of asymptotically flat BH perturbations, where the quasinormal ringing gives way to a power-law cutoff [ref] , and its occurrence is related to the asymptotic nature of timelike infinity in AdS spacetimes which serves as a reflective boundary.

    Echoes of Compact Objects in Scalar-Tensor Theories of Gravity · Black hole · 0.91

Cites it as background 9 papers

Discussion

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