Pith Number

pith:R4M6ODVA

pith:2026:R4M6ODVAX6ZTDJGGWDZZPJR4WA

not attested not anchored not stored refs resolved

Mapping the emission and spectral properties of the FRI radio galaxy 3C 449 with LOFAR and the VLA

Judith H. Croston, Luca Ricci, Luisa Ostorero, Martin J. Hardcastle, Raffaella Morganti, Timothy W. Shimwell

Spectral ages reach about 150 million years at the outer edges of 3C 449, implying supersonic average jet expansion speeds.

arxiv:2604.12043 v1 · 2026-04-13 · astro-ph.HE

Open paper page JSON Open Graph Bundle Merged state Verified badge What is a Pith Number?

Add to your LaTeX paper

\usepackage{pith}
\pithnumber{R4M6ODVAX6ZTDJGGWDZZPJR4WA}

Prints a linked badge after your title and injects PDF metadata. Compiles on arXiv. Learn more · Embed verified badge

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

At the outer edges of both the northern tail and southern lobe, the spectral age is ~150 Myr. If the latter age were representative of the dynamical source age, the average expansion speed of both jets during the source lifetime would be supersonic, with Mach numbers of M~4.1 and M~2.8 for the northern and southern jets, respectively.

C2weakest assumption

The modeling assumes equipartition between particle and magnetic field energies together with a constant magnetic field strength across the entire source, and that the derived spectral ages can be directly compared to the dynamical age without significant particle re-acceleration on scales of hundreds of kpc.

C3one line summary

New spectral index maps of 3C 449 show a flat spectrum in the inner jets that steepens outward, yielding radiative ages of ~150 Myr at the lobe edges and implying supersonic average expansion speeds if those ages represent the full dynamical lifetime.

References

2 extracted · 2 resolved · 0 Pith anchors

[1] 1992, A&AS, 93, 331 Astropy Collaboration, Price-Whelan, A 1992

[2] The spectral evolution inferred with both KP’s and Tribble’s model is com- parable to that inferred from JP’s model within 1σ(see Sect 2003

Cited by

1 paper in Pith

The ultra low-frequency spectral properties of bright extended radio galaxies in the 3CRR catalogue

Receipt and verification

First computed	2026-06-19T16:10:37.335812Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

8f19e70ea0bfb331a4c6b0f397a63cb03e19f71e8821119b3549a30db5a56e15

Aliases

arxiv: 2604.12043 · arxiv_version: 2604.12043v1 · doi: 10.48550/arxiv.2604.12043 · pith_short_12: R4M6ODVAX6ZT · pith_short_16: R4M6ODVAX6ZTDJGG · pith_short_8: R4M6ODVA

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/R4M6ODVAX6ZTDJGGWDZZPJR4WA \
  | 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: 8f19e70ea0bfb331a4c6b0f397a63cb03e19f71e8821119b3549a30db5a56e15

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "3d5235dbe53dd19189cf972846c6f8c2fa83439f0b2ae19154017947fca349fe",
    "cross_cats_sorted": [],
    "license": "http://creativecommons.org/licenses/by-sa/4.0/",
    "primary_cat": "astro-ph.HE",
    "submitted_at": "2026-04-13T20:36:26Z",
    "title_canon_sha256": "eebbd3da1a65e587add9b031b3beaa1af9e92a59d262428ed8bc8d2d586486bb"
  },
  "schema_version": "1.0",
  "source": {
    "id": "2604.12043",
    "kind": "arxiv",
    "version": 1
  }
}