Where Galaxies Point: First Measurement of the Large-Scale Axial Intrinsic Alignment
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arXiv
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| Autori principali: | , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| author | Ferreira, Pedro da Silveira Ramos, Rafael Oliveira Ferreira, Paula S. Cortesi, Arianna Ferrari, Fabricio Marra, Valerio Bom, Clécio R. |
| author_facet | Ferreira, Pedro da Silveira Ramos, Rafael Oliveira Ferreira, Paula S. Cortesi, Arianna Ferrari, Fabricio Marra, Valerio Bom, Clécio R. |
| contents | Applying a new estimator to the Dark Energy Survey (DES) Y3 weak lensing shape catalog, we map the galaxies' orientation field and report the first detection of a large-scale axial intrinsic alignment (LAIA) on dipolar angular scales. Ellipticals' semi-major axes and spirals' semi-minor axes coherently point toward a common direction, (RA,Dec)=$(306^{+6}_{-4},52^{+3}_{-3})^\circ$ and $(296^{+10}_{-18},50^{+6}_{-2})^\circ$, respectively, with amplitudes in the expected tidal-torquing hierarchy. This pattern could be produced by a horizon-scale tidal field imprinted by primordial inhomogeneities during galaxy assembly and, if confirmed, would signal a statistically significant preferred direction in the Universe, thereby probing deviations from statistical isotropy. The signal persists across spatial and redshift splits and is difficult to attribute to survey systematics. LAIA offers a new sky-wide compass linking galaxy evolution and cosmology. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_10005 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Where Galaxies Point: First Measurement of the Large-Scale Axial Intrinsic Alignment Ferreira, Pedro da Silveira Ramos, Rafael Oliveira Ferreira, Paula S. Cortesi, Arianna Ferrari, Fabricio Marra, Valerio Bom, Clécio R. Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies Applying a new estimator to the Dark Energy Survey (DES) Y3 weak lensing shape catalog, we map the galaxies' orientation field and report the first detection of a large-scale axial intrinsic alignment (LAIA) on dipolar angular scales. Ellipticals' semi-major axes and spirals' semi-minor axes coherently point toward a common direction, (RA,Dec)=$(306^{+6}_{-4},52^{+3}_{-3})^\circ$ and $(296^{+10}_{-18},50^{+6}_{-2})^\circ$, respectively, with amplitudes in the expected tidal-torquing hierarchy. This pattern could be produced by a horizon-scale tidal field imprinted by primordial inhomogeneities during galaxy assembly and, if confirmed, would signal a statistically significant preferred direction in the Universe, thereby probing deviations from statistical isotropy. The signal persists across spatial and redshift splits and is difficult to attribute to survey systematics. LAIA offers a new sky-wide compass linking galaxy evolution and cosmology. |
| title | Where Galaxies Point: First Measurement of the Large-Scale Axial Intrinsic Alignment |
| topic | Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2511.10005 |