{
  "annotation_id": "bbac2228-aac4-4218-8e63-a797948d8da8",
  "date_created": "2026-02-17T05:53:15.226000Z",
  "date_modified": "2026-02-17T05:53:15.226000Z",
  "file_hash": "c42d72b6e1834c9597cf6b048be4d8c215f48f3f2953faaf2b7332acdd319ee5",
  "private": false,
  "record": {
    "abstract": "We present a new empirical relation between the standardized magnitude ($m$) of Type Ia supernovae (SNe Ia) and redshift ($z$). Using Pantheon+ and DES-SN5YR, we find a negative linear correlation between $m-5\\log(z(1+z))$ and $z$, implying that their magnitude--redshift relation can be parametrized with just two parameters: an intercept $\\mathcal{M}$ and a slope $b$. This relation corresponds to the luminosity distance $d_L(z)=c\\,H_0^{-1}z(1+z)10^{bz/5}$ and is valid up to at least $z\\simeq1.1$. It outperforms the $\\Lambda$CDM and flat $w$CDM models and the (2,1) Pad\\\u0027e approximant for $d_L(z)$, and performs comparably to the flat $\\Lambda$CDM model and the (2,1) Pad\\\u0027e($j_0=1$) model of Hu et al. Furthermore, the relation is stable in the absence of low-$z$ SNe, making it suitable for fitting Hubble diagrams of SNe Ia without the need to add a low-$z$ sample. In deep fields in particular, assuming that the large-scale density is independent of the comoving radial coordinate, $b\\propto q_0+1$. We fit the empirical relation to SN data in eight deep-field regions and find that their fitted $\\mathcal{M}$ and $b$ parameters are consistent within $1.6\\,\\sigma$, in agreement with isotropy. The inferred $q_0$ values, ranging from $-0.6$ to $-0.4$, are consistent within $1.5\\,\\sigma$ and significantly lower than zero, indicating statistically consistent cosmic acceleration across all eight regions. We apply the empirical relation to the DES-Dovekie and Amalgame SN samples, finding $b$ values consistent with those from DES-SN5YR and Pantheon+. Finally, using the empirical relation in the hemispheric comparison method applied to Pantheon+ up to $z=1.1$, we find no evidence for anisotropies in $\\mathcal{M}$ and $b$.",
    "arxiv_id": "2601.08505",
    "authors": [
      "\u00d3smar Rodr\u00edguez",
      "Alejandro Clocchiatti"
    ],
    "categories": [
      "astro-ph.CO",
      "gr-qc"
    ],
    "license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
    "title": "A new magnitude--redshift relation based on SNe Ia",
    "url": "https://arxiv.org/abs/2601.08505",
    "version": "v1"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "09180507-f5fa-4dbe-8b05-92172b4aedca",
    "id": "arXiv Dataset",
    "type": "Model",
    "variant": "snapshot-2026-01-17",
    "version": "0.1.0"
  },
  "user_id": 1000002
}