Probing cosmic isotropy: Hubble constant and matter density large-angle variations with the Pantheon+SH0ES data
Fuente:
arXiv
Enregistré dans:
| Auteurs principaux: | , , , , |
|---|---|
| Format: | Preprint |
| Publié: |
2025
|
| Sujets: | |
| Accès en ligne: | |
| Tags: |
Ajouter un tag
Pas de tags, Soyez le premier à ajouter un tag!
|
| _version_ | 1866912750466236416 |
|---|---|
| author | Mokeddem, Rahima Lopes, Maria Avila, Felipe Bernui, Armando Hipólito-Ricaldi, Wiliam S. |
| author_facet | Mokeddem, Rahima Lopes, Maria Avila, Felipe Bernui, Armando Hipólito-Ricaldi, Wiliam S. |
| contents | In this study we investigate potential large-angle anisotropies in the angular distribution of the cosmological parameters $H_0$ (the Hubble constant) and $Ω_m$ (the matter density) in the flat-$Λ$CDM framework, using the Pantheon+SH0ES supernovae catalog. For this we perform a directional analysis by dividing the celestial sphere into a set of directions, and estimate the best-fit cosmological parameters across the sky using a MCMC approach. Our results show a dominant dipolar pattern for both parameters in study, suggesting a preferred axis in the universe expansion and in the distribution of matter. However, we also found that for $z \gtrsim 0.015$, this dipolar behavior is not statistically significant, confirming the expectation -- in the $Λ$CDM scenario -- of an isotropic expansion and a uniform angular distribution of matter (both results at $1\,σ$ confidence level). Nevertheless, for nearby supernovae, at distances $\lesssim 60$ Mpc or $z \lesssim 0.015$, the peculiar velocities introduce a highly significant dipole in the angular distribution of $H_0$. Furthermore, we perform various robustness tests that support our findings, and consistency tests of our methodology. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_00903 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Probing cosmic isotropy: Hubble constant and matter density large-angle variations with the Pantheon+SH0ES data Mokeddem, Rahima Lopes, Maria Avila, Felipe Bernui, Armando Hipólito-Ricaldi, Wiliam S. Cosmology and Nongalactic Astrophysics In this study we investigate potential large-angle anisotropies in the angular distribution of the cosmological parameters $H_0$ (the Hubble constant) and $Ω_m$ (the matter density) in the flat-$Λ$CDM framework, using the Pantheon+SH0ES supernovae catalog. For this we perform a directional analysis by dividing the celestial sphere into a set of directions, and estimate the best-fit cosmological parameters across the sky using a MCMC approach. Our results show a dominant dipolar pattern for both parameters in study, suggesting a preferred axis in the universe expansion and in the distribution of matter. However, we also found that for $z \gtrsim 0.015$, this dipolar behavior is not statistically significant, confirming the expectation -- in the $Λ$CDM scenario -- of an isotropic expansion and a uniform angular distribution of matter (both results at $1\,σ$ confidence level). Nevertheless, for nearby supernovae, at distances $\lesssim 60$ Mpc or $z \lesssim 0.015$, the peculiar velocities introduce a highly significant dipole in the angular distribution of $H_0$. Furthermore, we perform various robustness tests that support our findings, and consistency tests of our methodology. |
| title | Probing cosmic isotropy: Hubble constant and matter density large-angle variations with the Pantheon+SH0ES data |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2504.00903 |