New cosmic model challenges ΛCDM with holographic energy and Rastall gravity

A new study has explored an alternative model of the universe by combining New Tsallis holographic energy with Rastall gravity. Researchers N. Sadeghnezhad, R. Jalalzadeh, Z. Davari, and B. Afshar examined whether this approach could better explain cosmic expansion and dark energy. Their findings suggest the model aligns closely with current observational data while offering slight improvements over the standard ΛCDM framework. The team analysed the combined model using a wide range of cosmological datasets. These included Type Ia supernovae from PantheonPlus, Baryon Acoustic Oscillation (BAO) data from DESI, Hubble parameter measurements, and constraints from Big Bang Nucleosynthesis. By applying these observations, they determined strict bounds for the model’s parameters, particularly the Rastall parameter, which had to satisfy both thermodynamic and observational limits.

The results showed that the model accurately reproduces the universe’s expansion history. It also provided values for key quantities, such as the Hubble constant, that match existing measurements. Notably, the model’s predictions for expansion rates at intermediate redshifts fit observations slightly better than the standard ΛCDM model. The study further confirmed that the combined approach successfully accounts for the observed abundance of dark energy. It also revealed that only minor deviations from standard energy conservation are needed, hinting at a potential role for non-extensive statistical effects in dark energy behaviour. However, the analysis focused solely on background-level observations, leaving questions about cosmic structure formation and the early universe for future research.

The combined model of New Tsallis holographic energy and Rastall gravity presents a viable alternative to ΛCDM. It matches key cosmological observations while offering minor improvements in explaining expansion rates. Further work will be needed to explore its implications for cosmic structure and the early universe.