{"work":{"id":"3d99c2e7-7420-4107-a28a-1e5d4a9d2ed9","openalex_id":null,"doi":null,"arxiv_id":"2408.14628","raw_key":null,"title":"Investigating Late-Time Dark Energy and Massive Neutrinos in Light of DESI Y1 BAO","authors":null,"authors_text":"J","year":2024,"venue":"astro-ph.CO","abstract":"Baryonic Acoustic Oscillation (BAO) data from the Dark Energy Spectroscopic Instrument (DESI), in combination with Cosmic Microwave Background (CMB) data and Type Ia Supernovae (SN) luminosity distances, suggests a dynamical evolution of the dark energy equation of state with a phantom phase ($w < -1$) in the past when the so-called $w_0w_a$ parametrization $w(a) = w_0 + w_a(1-a)$ is assumed. In this work, we investigate more general dark energy models that also allow a phantom equation of state. We consider three cases: an equation of state with a transition feature, a model-agnostic equation of state with constant values in chosen redshift bins, and a k-essence model. Since the dark energy equation of state is correlated with neutrino masses, we reassess constraints on the neutrino mass sum focusing on the model-agnostic equation of state. We find that the combination of DESI BAO with Planck 2018 CMB data and SN data from Pantheon, Pantheon+, or Union3 is consistent with an oscillatory dark energy equation of state, while a monotonic behavior is preferred by the DESY5 SN data. Performing model comparison techniques, we find that the $w_0w_a$ parametrization remains the simplest dark energy model that can provide a better fit to DESI BAO, CMB, and all SN datasets than $\\Lambda$CDM. Constraints on the neutrino mass sum assuming dynamical dark energy are relaxed compared to $\\Lambda$CDM and we show that these constraints are tighter in the model-agnostic case relative to $w_0w_a$ model by $70\\%-90\\%$.","external_url":"https://arxiv.org/abs/2408.14628","cited_by_count":null,"metadata_source":"pith","metadata_fetched_at":"2026-07-08T15:55:05.022852+00:00","pith_arxiv_id":"2408.14628","created_at":"2026-05-14T21:04:03.864272+00:00","updated_at":"2026-07-08T15:55:05.022852+00:00","title_quality_ok":true,"display_title":"Rebouças, D","render_title":"Rebouças, D"},"hub":{"state":{"tier_text":"hub","tier":"hub","tier_reason":"10+ Pith inbound or 1,000+ external citations","pith_inbound_count":13,"external_cited_by_count":null},"tier":"hub","role_counts":[{"context_role":"background","n":10}],"polarity_counts":[{"context_polarity":"background","n":9},{"context_polarity":"unclear","n":1}],"runs":{},"summary":{},"graph":{},"authors":[]}}