Varying Alpha Generalized Dirac-Born-Infeld Models. (arXiv:2101.08584v1 [astro-ph.CO])

<a href="http://arxiv.org/find/astro-ph/1/au:+Tavares_V/0/1/0/all/0/1">V. C. Tavares</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martins_C/0/1/0/all/0/1">C. J. A. P. Martins</a>

We study the cosmological consequences of a class of Dirac-Born-Infeld

models, and assess their viability as a candidate for the recent acceleration

of the Universe. The model includes both the rolling tachyon field and the

generalized Chaplygin gas models as particular limits, and phenomenologically

each of these provides a possible mechanism for a deviation of the value of the

dark energy equation of state from its canonical (cosmological constant) value.

The field-dependent potential that is characteristic of the rolling tachyon

also leads to variations of the fine-structure constant $alpha$, implying that

the model can be constrained both by standard cosmological probes and by

astrophysical measurements of $alpha$. Our analysis, using the latest

available low-redshfit data and local constraints from atomic clock and weak

equivalence principle experiments, shows that the two possible deviations of

the dark energy equation of state are constrained to be

$log_{10}{(1+w_0)_V}<-7.85$ and $log_{10}{(1+w_0)_C}<-0.85$, respectively for

the rolling tachyon and Chaplygin components, both being at the $95.4%$

confidence level (although the latter depends on the choice of priors, in a way

that we quantify). Alternatively, the $95.4%$ confidence level bound on the

dimensionless slope of the potential is $log_{10}{lambda}<-5.36$. This

confirms previous analyses indicating that in these models the potential needs

to be extremely flat.

We study the cosmological consequences of a class of Dirac-Born-Infeld

models, and assess their viability as a candidate for the recent acceleration

of the Universe. The model includes both the rolling tachyon field and the

generalized Chaplygin gas models as particular limits, and phenomenologically

each of these provides a possible mechanism for a deviation of the value of the

dark energy equation of state from its canonical (cosmological constant) value.

The field-dependent potential that is characteristic of the rolling tachyon

also leads to variations of the fine-structure constant $alpha$, implying that

the model can be constrained both by standard cosmological probes and by

astrophysical measurements of $alpha$. Our analysis, using the latest

available low-redshfit data and local constraints from atomic clock and weak

equivalence principle experiments, shows that the two possible deviations of

the dark energy equation of state are constrained to be

$log_{10}{(1+w_0)_V}<-7.85$ and $log_{10}{(1+w_0)_C}<-0.85$, respectively for

the rolling tachyon and Chaplygin components, both being at the $95.4%$

confidence level (although the latter depends on the choice of priors, in a way

that we quantify). Alternatively, the $95.4%$ confidence level bound on the

dimensionless slope of the potential is $log_{10}{lambda}<-5.36$. This

confirms previous analyses indicating that in these models the potential needs

to be extremely flat.

http://arxiv.org/icons/sfx.gif