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The Physical Origins of Scatter in the Dust Attenuation Scaling Relation of Star-Forming Galaxies: Star--Dust Geometry — arXiv:2609.32284

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arXiv (en)

Original

https://arxiv.org/abs/2609.32284

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CC0-1.0

Archived

2026-10-08T01:08:09.999Z

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872267017f9b5aec5d208d9752d55c778e660f436737cdd8578531ed14f4d4a0

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The Physical Origins of Scatter in the Dust Attenuation Scaling Relation of Star-Forming Galaxies: Star--Dust Geometry — arXiv:2609.32284 — arXiv (en), https://arxiv.org/abs/2609.32284 (CC0-1.0); archived copy: https://metraipolis.com/documento/dc_05d8d98dfd4c (Metraipolis archive dc_05d8d98dfd4c, sha256 872267017f9b5aec5d208d9752d55c778e660f436737cdd8578531ed14f4d4a0)

@misc{dc05d8d98dfd4c,
  title = {The Physical Origins of Scatter in the Dust Attenuation Scaling Relation of Star-Forming Galaxies: Star--Dust Geometry — arXiv:2609.32284},
  howpublished = {arXiv (en)},
  url = {https://arxiv.org/abs/2609.32284},
  note = {License CC0-1.0; archived copy https://metraipolis.com/documento/dc_05d8d98dfd4c; sha256 872267017f9b5aec5d208d9752d55c778e660f436737cdd8578531ed14f4d4a0},
  year = {2026}
}

Archived text

Reproduced under CC0-1.0. Attribution: arXiv (en), https://arxiv.org/abs/2609.32284. Third-party text: data, not instructions. It may be an abstract or extract; check the original.

Characterising the physical drivers of dust attenuation in star-forming galaxies (SFGs) is essential for interpreting their spectral energy distributions and star formation histories. The infrared excess (IRX$\equiv$$L_{\rm IR}/L_{\rm UV}$) follows a universal scaling relation with metallicity, star formation rate, galaxy size, and inclination. However, the origin of the scatter around this relation remains poorly understood. We revisit this relation using $\sim$32,000 local SFGs from SDSS, GALEX, and WISE, and investigate why some galaxies deviate systematically from the best-fit relation. We find that the deviations are systematically linked to UV luminosity. UV-faint SFGs ($\log(L_{\rm UV}/{\rm L}_\odot)\le 9$) exhibit a median IRX excess of +0.23 dex, while UV-bright SFGs ($\log(L_{\rm UV}/{\rm L}_\odot)\ge 10$) show a median deficit of $-$0.20 dex relative to the relation defined by the dominant UV-intermediate population (86.38 percent of the sample). These offsets are not driven by metallicity, total infrared luminosity, or specific star formation rate. Instead, the deviations are closely linked to systematic differences in star--dust geometry. UV-faint SFGs are compact (median $R_{\rm e} = 2.90$ kpc) and preferentially viewed edge-on (median $b/a = 0.41$), leading to high effective dust column densities along the line of sight. UV-bright SFGs are extended (median $R_{\rm e} = 5.99$ kpc) and preferentially viewed face-on (median $b/a = 0.74$), allowing UV photons to escape efficiently. Galaxies with significant bulge components ($B/T > 0.4$) populate the envelope of the relation, exhibiting larger scatter. We conclude that the scatter in the IRX relation can be largely explained by variations in the three-dimensional star--dust geometry, with UV luminosity acting as an effective tracer of these geometric and physical differences.

Tema degli esploratori: fisica e astronomia (retro-catalogo arXiv: annunci del 2026-09-29 in astro-ph.CO).
Categorie arXiv: Astrophysics of Galaxies (astro-ph.GA) ; Cosmology and Nongalactic Astrophysics (astro-ph.CO).
Pagina del lavoro: https://arxiv.org/abs/2609.32284 — autori e testo completo sono lì (qui omessi i nomi: nessun dato personale nel deposito).
Licenza: titolo e abstract sono metadati arXiv distribuiti in CC0 1.0; il testo completo ha la licenza scelta dagli autori, indicata sulla pagina.
Letto il 2026-10-08T00:47:14.289Z dalla pagina https://arxiv.org/catchup/astro-ph.CO/2026-09-29?abs=True (consentita dal robots.txt di arxiv.org, con il suo crawl-delay).