Pith Number

pith:5SVUXZA6

pith:2026:5SVUXZA6UW7QSFYBU4TL4XSK3S

not attested not anchored not stored refs resolved

Probing the IMF in the Early Universe -- Direct measurements in the Bo\"otes I UFD with JWST/NIRCam

Alessandro Savino, Annalisa Calamida, Cheyanne Shariat, Daniel R. Weisz, Denija Crnojevi\'c, Evan N. Kirby, Joshua D. Simon, Kareem El-Badry, Keyi Ding, Kristen. B. W. McQuinn, Mario Gennaro, Marla Geha, Martha L. Boyer, Massimo Ricotti, Matteo Correnti, Nitya Kallivayalil, Puragra Guhathakurta, Rachael L. Beaton, Roberto J. Avila, Roger E. Cohen, Santi Cassisi, Thomas M. Brown, Vedant Chandra

The initial mass function measured in the ultra-faint dwarf Boötes I matches the Milky Way form at metallicities as low as one-hundredth solar.

arxiv:2605.15069 v1 · 2026-05-14 · astro-ph.GA · astro-ph.SR

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\usepackage{pith}
\pithnumber{5SVUXZA6UW7QSFYBU4TL4XSK3S}

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Record completeness

1 Bitcoin timestamp

2 Internet Archive

3 Author claim open · sign in to claim

4 Citations open

5 Replications open

✓ Portable graph bundle live · download bundle · merged state

The bundle contains the canonical record plus signed events. A mirror can host it anywhere and recompute the same current state with the deterministic merge algorithm.

Claims

C1strongest claim

Our best-fit broken power-law and lognormal IMF parameters are consistent with the Milky Way within 68% confidence level, providing evidence that star formation at metallicities as low as [Fe/H]≈-2.4 follows a similar IMF as in the Milky Way.

C2weakest assumption

Treating Boötes I as a local relic analogous to a high-redshift galaxy with stellar mass ≲10^5 M⊙ at z≳6; differences in dynamical history, gas conditions, or unresolved binaries could alter the inferred IMF.

C3one line summary

The low-mass IMF in Boötes I is consistent with the Milky Way within 68% confidence for broken power-law and lognormal forms, indicating universality at low metallicity.

References

72 extracted · 72 resolved · 4 Pith anchors

[1] P., Tollerud , E 2013 · doi:10.1051/0004-6361/201322068

[2] R., & Meyer, M 2010 · doi:10.1146/annurev-astro-082708-101642

[3] Bate, M. R. 2014, MNRAS, 442, 285, doi: 10.1093/mnras/stu795 2014 · doi:10.1093/mnras/stu795

[4] Bate, M. R. 2019, MNRAS, 484, 2341, doi: 10.1093/mnras/stz103 2019 · doi:10.1093/mnras/stz103

[5] 2022, MNRAS, 510, 3531, doi: 10.1093/mnras/stab3629 2022 · doi:10.1093/mnras/stab3629

Formal links

2 machine-checked theorem links

Receipt and verification

First computed	2026-05-17T21:40:26.033223Z
Last reissued	2026-05-17T21:57:19.339515Z
Builder	pith-number-builder-2026-05-17-v1
Signature	unsigned_v0
Schema	pith-number/v1.0

Canonical hash

ecab4be41ea5bf091701a726be5e4adc8a8be0efac13ba3906bf2827f7485818

Aliases

arxiv: 2605.15069 · arxiv_version: 2605.15069v1 · pith_short_12: 5SVUXZA6UW7Q · pith_short_16: 5SVUXZA6UW7QSFYB · pith_short_8: 5SVUXZA6

Agent API

Resolver JSON Graph JSON Events JSON Schema Signing key

Verify this Pith Number yourself

curl -sH 'Accept: application/ld+json' https://pith.science/pith/5SVUXZA6UW7QSFYBU4TL4XSK3S \
  | jq -c '.canonical_record' \
  | python3 -c "import sys,json,hashlib; b=json.dumps(json.loads(sys.stdin.read()), sort_keys=True, separators=(',',':'), ensure_ascii=False).encode(); print(hashlib.sha256(b).hexdigest())"
# expect: ecab4be41ea5bf091701a726be5e4adc8a8be0efac13ba3906bf2827f7485818

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "1ca28e734e708e86c3e17cb78f2da20db568b09b4a59fc4786fd2ef80596495c",
    "cross_cats_sorted": [
      "astro-ph.SR"
    ],
    "license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
    "primary_cat": "astro-ph.GA",
    "submitted_at": "2026-05-14T16:57:37Z",
    "title_canon_sha256": "445dda6302da388e43564ac8641ecd9ff540c447acf9d05f45069ccb8b9614dc"
  },
  "schema_version": "1.0",
  "source": {
    "id": "2605.15069",
    "kind": "arxiv",
    "version": 1
  }
}