Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Dark torsion as the cosmic speed-up

Gabriel Bengochea, Rafael Ferraro

TL;DR

The paper tackles the problem of cosmic acceleration without dark energy by proposing a modified teleparallel gravity based on the torsion scalar $L_T$. It develops a second-order, $f(L_T)$ framework with $f(L_T)=L_T-\alpha(-L_T)^{-n}$ and derives the modified Friedmann equation, then constrains the model using type Ia supernovae, BAO, and CMB data. The joint analysis yields best-fit values $n=-0.10$ and $\Omega_m=0.27$, predicting a transition to acceleration at $z_{acc}\approx0.74$ and reproducing the standard radiation and matter-dominated epochs; phantom behavior is avoided in the preferred parameter range. Overall, the work demonstrates a viable, simpler alternative to dark energy, where torsion in teleparallel gravity can explain the cosmic speed-up while preserving standard cosmology, consistent with current observations.

Abstract

It is shown that the recently detected acceleration of the universe can be understood by considering a modification of the teleparallel equivalent of General Relativity (TEGR), with no need of dark energy. The solution also exhibits phases dominated by matter and radiation as expected in the standard cosmological evolution. We perform a joint analysis with measurements of the most recent type Ia supernovae (SNe Ia), Baryon Acoustic Oscillation (BAO) peak and estimates of the CMB shift parameter data to constraint the only new parameter this theory has.

Dark torsion as the cosmic speed-up

TL;DR

The paper tackles the problem of cosmic acceleration without dark energy by proposing a modified teleparallel gravity based on the torsion scalar . It develops a second-order, framework with and derives the modified Friedmann equation, then constrains the model using type Ia supernovae, BAO, and CMB data. The joint analysis yields best-fit values and , predicting a transition to acceleration at and reproducing the standard radiation and matter-dominated epochs; phantom behavior is avoided in the preferred parameter range. Overall, the work demonstrates a viable, simpler alternative to dark energy, where torsion in teleparallel gravity can explain the cosmic speed-up while preserving standard cosmology, consistent with current observations.

Abstract

It is shown that the recently detected acceleration of the universe can be understood by considering a modification of the teleparallel equivalent of General Relativity (TEGR), with no need of dark energy. The solution also exhibits phases dominated by matter and radiation as expected in the standard cosmological evolution. We perform a joint analysis with measurements of the most recent type Ia supernovae (SNe Ia), Baryon Acoustic Oscillation (BAO) peak and estimates of the CMB shift parameter data to constraint the only new parameter this theory has.

Paper Structure

This paper contains 4 sections, 24 equations, 5 figures.

Table of Contents

  1. Introduction
  2. General considerations. Field equations
  3. Cosmological solution and observational constraints
  4. Conclusions

Figures (5)

  • Figure 1: Hubble diagram for 307 SNe Ia from the Union sample kowalski. The curves correspond to the concordance model $\Lambda CDM$ with $\Omega_\Lambda$=0.74 and $\Omega_m$=0.26 (dotted line), and our models with the values corresponding to the best-fit $\Omega_m$=0.42 and $n$=1.30 (dashed line) and also with those coming from the joint analysis of SNIa+BAO+CMB, $\Omega_m$=0.27 and $n$=-0.10 (solid line).
  • Figure 2: Distance modulus residual from the $\Lambda CDM$ model for the same values from Figure \ref{['datasn']}.
  • Figure 3: Confidence intervals at 68.3%, 95.4% y 99.7% in the $n-\Omega_m$ plane coming from combining SNe Ia, BAO and CMB data. The best-fit to this joint analysis is reached with the values $n=-0.10$ and $\Omega_m=0.27$.
  • Figure 4: The curves correspond to the total equation of state as a function of $z$ expected for the standard concordance model $\Lambda CDM$ with $\Omega_\Lambda$=0.74 and $\Omega_m$=0.26 (dashed line), and for our model (solid line) with the values of the best-fit coming from SNIa+BAO+CMB, $\Omega_m$=0.27 and $n$=-0.10. Three cosmological phases observed.
  • Figure 5: Effective equation of state as a function of $z$ for our model with the values of the best-fit coming from SNIa+BAO+CMB, $\Omega_m$=0.27 and $n$=-0.10.