Cosmic Structure SIG Seminar

Constraints on Dynamical Dark Energy from the Full Dark Energy Survey

Speaker

Sujeong Lee, Ohio University

Abstract

The nature of dark energy remains one of the central open questions in cosmology, and recent analyses have reported a weak but intriguing preference for an evolving equation of state. I will present constraints on the w0-wa parameterization from the full six-year Dark Energy Survey (DES) dataset, combining growth and geometric probes — supernovae, BAO, and weak lensing and galaxy clustering (3x2pt) — within a single survey. The DES-only combination yields the tightest such constraints using multiple probes from any single survey, and adding external CMB and DESI BAO data gives a 3.0-sigma deviation from a cosmological constant, with the best-fit always favoring w0 > -1, wa < 0. Because DES relies on different probes and systematics than DESI, this provides an independent cross-check on the recent hints for dynamical dark energy. I will discuss how to interpret these results, and what they imply for Stage IV surveys. This work realizes the multi-probe dark energy program envisioned at the inception of DES.

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