Dark energy and neutrinos along the cosmic expansion history
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arXiv
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| Format: | Preprint |
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2025
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| author | Ghedini, Pietro Hajjar, Rasmi Mena, Olga |
| author_facet | Ghedini, Pietro Hajjar, Rasmi Mena, Olga |
| contents | Recent cosmological measurements are hinting that dark energy may evolve, with its equation of state, $w_\mathrm{DE}$, even showing oscillatory patterns. In this work, we employ a model-independent approach to jointly reconstruct $w_\mathrm{DE}$ and the sum of neutrino masses, $\sum m_ν$, adopting the PCHIP method with seven fixed nodes in which we allow the two parameters to vary. We employ CMB, Baryon Acoustic Oscillations and Supernovae Ia data to constrain the values of $w_\mathrm{DE}$ and $\sum m_ν$ at each node. We conduct three different analyses in which we reconstruct $w_\mathrm{DE}$: one with fixed $\sum m_ν=0.06~\mathrm{eV}$; one in which we allow $\sum m_ν$ to vary, and one in which we also reconstruct $\sum m_ν$ using the PCHIP method. We find the dark energy equation of state to be consistent with the cosmological constant scenario, except when including DESI data and allowing for phantom crossing, where we find a $95\%$ CL deviation from $w_\mathrm{DE}=-1$ around $z\sim1.2$. For neutrino masses, we obtain looser constraints when focusing on phantom dark energy, that show further early and late relaxation when reconstructing the mass via the PCHIP method. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_16781 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Dark energy and neutrinos along the cosmic expansion history Ghedini, Pietro Hajjar, Rasmi Mena, Olga Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology Recent cosmological measurements are hinting that dark energy may evolve, with its equation of state, $w_\mathrm{DE}$, even showing oscillatory patterns. In this work, we employ a model-independent approach to jointly reconstruct $w_\mathrm{DE}$ and the sum of neutrino masses, $\sum m_ν$, adopting the PCHIP method with seven fixed nodes in which we allow the two parameters to vary. We employ CMB, Baryon Acoustic Oscillations and Supernovae Ia data to constrain the values of $w_\mathrm{DE}$ and $\sum m_ν$ at each node. We conduct three different analyses in which we reconstruct $w_\mathrm{DE}$: one with fixed $\sum m_ν=0.06~\mathrm{eV}$; one in which we allow $\sum m_ν$ to vary, and one in which we also reconstruct $\sum m_ν$ using the PCHIP method. We find the dark energy equation of state to be consistent with the cosmological constant scenario, except when including DESI data and allowing for phantom crossing, where we find a $95\%$ CL deviation from $w_\mathrm{DE}=-1$ around $z\sim1.2$. For neutrino masses, we obtain looser constraints when focusing on phantom dark energy, that show further early and late relaxation when reconstructing the mass via the PCHIP method. |
| title | Dark energy and neutrinos along the cosmic expansion history |
| topic | Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2512.16781 |