USR-2026-0048 · Galactic dynamics

The GD-1 stellar stream shows no statistically significant density gap. The deepest local under-density (z = −5.0 in a single bin at φ₁ = −21°) has a look-elsewhere-corrected global significance of p = 0.587 across 39 bins and 5000 smooth+Poisson simulations — consistent with an unperturbed stream.

PROVISIONAL global p = 0.587 — not significant re-run & confirmed 2026-07-12 (R0 — founder CI; independence pending)

A look-elsewhere-corrected search for a dark-substructure impact gap in GD-1 returns a clean null: the deepest local dip is not globally significant (p = 0.59).

Falsify-box — how to kill this claim

SURVIVED any density gap reaches global significance p < 0.01 after look-elsewhere correction

Verification record — every quoted number, re-run 2026-07-12

quantity	measured	verdict
deepest local under-density	z = −5.0 (single bin, φ₁ = −21°)	MATCH
global significance (look-elsewhere corrected)	p = 0.587 (39 bins, 5000 sims)	MATCH

Provenance

script: _gd1_gap_test.py
script status: PRESENT
datasets: GD-1 stream members (Gaia + PS1) · claim-scripts (downloadable from /data — run it yourself) · gd1-tidal-stream (downloadable from /data — run it yourself)
re-run: 2026-07-12

Status, honestly

standing null: no globally significant gap after look-elsewhere correction. Status here is computed from evidence — the author cannot set it, and neither can we. Independent reproduction would move it; nothing else will.

§ Reproduction _gd1_gap_test.py

The founder's own run of this script, captured verbatim. A match proves the result is reproducible; it is still R0 on this registry's independence rings — same code, so it cannot move a status. Only an outside run does that.

sha256 3fa8976d72f938634d7c4f06… size 3919 B exit 0 runtime 1.7s env python 3.12.2 · numpy 1.26.4 determinism byte-stable

A · Recorded founder's machine · 2026-08-02

stars=43311  stream>0.5:1001  spur>0.5:86
phi1 range [-92,10]  phi2 range [-5,5]
on-stream (stream>0.2,|phi2|<2,-90<phi1<-10): N=991, sum(w)=802

CONTROL: spur stars (spur>0.3, -45<phi1<-25): N=118, median phi2=+1.14 (spur is off-track at phi2~+0.5..+1)

rho(phi1) vs smooth model (z = (rho-model)/poisson):
  phi1=-87.0  rho=   0.7  model=   0.1  z=+1.20  N=2
  phi1=-85.0  rho=   0.3  model=   0.2  z=+0.25  N=1
  phi1=-83.0  rho=   0.0  model=   0.3  z=-0.34  N=0
  phi1=-81.0  rho=   2.0  model=   0.6  z=+1.22  N=3
  phi1=-79.0  rho=   2.7  model=   1.0  z=+1.27  N=4
  phi1=-77.0  rho=   5.6  model=   1.5  z=+2.17  N=9
  phi1=-75.0  rho=   7.0  model=   2.4  z=+2.19  N=11
  phi1=-73.0  rho=   4.4  model=   3.6  z=+0.55  N=8
  phi1=-71.0  rho=   4.8  model=   5.1  z=-0.17  N=9
  phi1=-69.0  rho=   4.5  model=   7.1  z=-1.59  N=8
  phi1=-67.0  rho=  14.8  model=   9.5  z=+1.56  N=19
  phi1=-65.0  rho=   5.7  model=  12.3  z=-3.33  N=8 <== GAP
  phi1=-63.0  rho=  12.5  model=  15.4  z=-0.87  N=14
  phi1=-61.0  rho=  11.4  model=  18.8  z=-2.57  N=16 <== GAP
  phi1=-59.0  rho=  19.3  model=  22.1  z=-0.69  N=23
  phi1=-57.0  rho=  26.0  model=  25.3  z=+0.15  N=30
  phi1=-55.0  rho=  20.7  model=  28.1  z=-1.86  N=27
  phi1=-53.0  rho=  44.8  model=  30.5  z=+2.26  N=50
  phi1=-51.0  rho=  44.2  model=  32.2  z=+1.92  N=50
  phi1=-49.0  rho=  39.2  model=  33.3  z=+1.01  N=45
  phi1=-47.0  rho=  48.3  model=  33.7  z=+2.27  N=56
  phi1=-45.0  rho=  38.4  model=  33.4  z=+0.86  N=45
  phi1=-43.0  rho=  26.1  model=  32.7  z=-1.43  N=32
  phi1=-41.0  rho=  25.2  model=  31.5  z=-1.50  N=36 (spur/known -40 gap region)
  phi1=-39.0  rho=  20.8  model=  30.1  z=-2.42  N=29 <== GAP
  phi1=-37.0  rho=  25.6  model=  28.5  z=-0.65  N=33 (spur/known -40 gap region)
  phi1=-35.0  rho=  21.9  model=  26.9  z=-1.19  N=27 (spur/known -40 gap region)
  phi1=-33.0  rho=  24.9  model=  25.3  z=-0.09  N=32 (spur/known -40 gap region)
  phi1=-31.0  rho=  23.2  model=  23.8  z=-0.14  N=26 (spur/known -40 gap region)
  phi1=-29.0  rho=  38.2  model=  22.6  z=+2.71  N=44 (spur/known -40 gap region)
  phi1=-27.0  rho=  31.7  model=  21.6  z=+1.94  N=37 (spur/known -40 gap region)
  phi1=-25.0  rho=  35.2  model=  21.0  z=+2.59  N=41 (spur/known -40 gap region)
  phi1=-23.0  rho=  27.6  model=  20.7  z=+1.47  N=34 (spur/known -40 gap region)
  phi1=-21.0  rho=   8.3  model=  20.8  z=-5.02  N=11 <== GAP
  phi1=-19.0  rho=  11.9  model=  21.5  z=-3.05  N=14 <== GAP
  phi1=-17.0  rho=  23.4  model=  22.9  z=+0.11  N=29
  phi1=-15.0  rho=  30.6  model=  25.3  z=+1.11  N=41
  phi1=-13.0  rho=  35.1  model=  29.0  z=+1.13  N=42
  phi1=-11.0  rho=  34.6  model=  34.8  z=-0.03  N=45

most significant under-density: phi1=-21.0, z=-5.02
global p(any bin this deep under smooth+Poisson model) = 0.587  (39 bins, 5000 sims)

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