Speaker
Description
More than a decade ago, a Born--Infeld type tachyonic dark energy model raised considerable interest, being able to drive the evolution of the universe to the presently dark energy dominated regime. Depending on the model parameters, a six-fold evolution turned possible. Early confrontation with Supernovae Ia and Hubble parameter data disruled evolutions of type IV and V. Further, the evolutions I and IIa were disruled by nucleosynthesis and stability arguments. Hence, only the evolutions IIb and III survived. They also survived CMB constraints imposed through a modified CAMB code.
These two types of evolutions are qualitatively very different. While both start from a Big Bang type initial singularity and both exhibit an accelerating phase nowadays, their future evolution could not differ more. IIb tends towards an exponentially expanding de Sitter attractor, similarly to LCDM. However, III passes from a subluminal evolution through luminal evolution into a tachyonic regime and eventually reaches in finite time the future soft singularity dubbed Big Brake, which is traversable for point particles, followed by a contraction phase.
We report on ongoing work aimed to retest the evolutions IIb and III with the currently available, most precise Supernovae Ia data from the Pantheon+ set. With their increased accuracy these investigations may provide a more conclusive answer on which type of tachyonic universe evolution is allowed by data: the one leading to de Sitter or the other one leading to a Big Brake?
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| Internet talk | No |
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| Is this an abstract from experimental collaboration? | No |
| Name of experiment and experimental site | - |
| Is the speaker for that presentation defined? | No |