Speaker: George Efstathiou (Cambridge)

Title: The Evidence for Dynamical Dark Energy

Abstract: The Dark Energy Spectroscopic Instrument (DESI) collaboration has
measured baryon acoustic oscillation (BAO) features over a wide range
of redshifts with unprecedented precision. They argue that the data
provide evidence for evolving dark energy, quoting 'significance'
levels of 2.5-4.5 sigma depending on which additional data (CMB
anisotropies and supernovae) are added to the BAO data. The favoured
model of dynamical dark energy is unusual, requiring phantom-like
behaviour at high redshift. I will present a different way of looking
at the DESI data that provides simple and robust tests of consistency
with the LCDM cosmology. I find no evidence for a deviation from LCDM
and my analysis explains the degeneracy direction in the w_0-w_a plane
found by the DESI collaborations. I will summarize some recent work on
type Ia Supernova (SN) that supports my earlier claims that SN
catalogues are not yet accurate enough to constrain models of
dynamical dark energy.

• Date:
  Feb. 12, 2026, 2:30 p.m. – 3:30 p.m.
  
  
• Location:

  AIP; Kirch building, Conference room

  
  
• Contact:
  Ewald Puchwein
  epuchwein@aip.de