Symbol w
w is part of the quantity the equation computes from the expression on the right.
Read this term in its guide →Published equation contexts
Why this formula appears here
Evolving dark energy , in the w0-wa parametrization, keeps the sound horizon alone and instead lets dark energy’s equation of state change with cosmic time: . where a is the cosmic scale factor (a = 1 today) and w = -1 recovers a plain cosmological constant. This is the family DESI’s DR2 BAO release put back on the table: fit jointly to DESI BAO, Planck CMB, and supernovae, a w0-wa model is preferred over flat LambdaCDM at up to several sigma, with the preferred trajectory suggesting dark energy was somewhat more negative than -1 in the past and is evolving toward less negative values now [ 3 , 4 ] .
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Symbol a
a is an argument of the function-like quantity on the left; its role is set by that function’s stated inputs.
Read this term in its guide →Symbol w_0
is one of the signed contributions combined to compute the quantity on the left.
Read this term in its guide →Symbol w_a
is one of the signed contributions combined to compute the quantity on the left.
Read this term in its guide →How to interpret it
Read it with the definitions, units, and assumptions supplied by the article.
Research cited beside this formula
- [5] Early Dark Energy Can Resolve The Hubble Tension ↗
- [6] The Ups and Downs of Early Dark Energy solutions to the Hubble tension: a review of models, hints and constraints circa 2023 ↗
- [4] Extended Dark Energy analysis using DESI DR2 BAO measurements ↗
- [3] DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints ↗
Published contexts (1)
A symbol can carry a different meaning in another article. Each occurrence keeps its own guide and term definitions.
Equation 4 · Astronomy & Cosmology
Comparing the Main Approaches to Precision Cosmology
This equation states an equality: the expressions on both sides have the same value under the article’s assumptions.
Evolving dark energy , in the w0-wa parametrization, keeps the sound horizon alone and instead lets dark energy’s equation of state change with cosmic time: . where a is the cosmic scale factor (a = 1 today) and w = -1 recovers a plain cosmological constant. This is the family DESI’s DR2 BAO release put back on the table: fit jointly to DESI BAO, Planck CMB, and supernovae, a w0-wa model is preferred over flat LambdaCDM at up to several sigma, with the preferred trajectory suggesting dark energy was somewhat more negative than -1 in the past and is evolving toward less negative values now [ 3 , 4 ] .
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