Model-independent reconstruction of cosmic thermodynamics and dark energy dynamics

Model-independent reconstruction of cosmic thermodynamics and dark energy dynamics
Afaq Maqsood, Tanima Duary
arXiv:2604.18723v1 Announce Type: new
Abstract: We perform a model-independent investigation of the thermodynamic evolution of the Universe by reconstructing the expansion history from observational data using Gaussian Process regression. We consider three independent combinations of datasets, namely CC32+DESI DR2+Pantheon+, CC32+DESI DR2+Union3, and CC32+DESI DR2+DES Y5, allowing us to assess the impact of different supernova samples on the reconstruction. From the reconstructed Hubble parameter and its derivatives over the redshift range 0 to 2, we evaluate key thermodynamic quantities associated with the apparent horizon, including the diagnostic function $P(z)$, the entropy production rate $dot{S}_{mathrm{tot}}$, and its second derivative $ddot{S}_{mathrm{tot}}$. We find that $P(z)$ remains positive across all redshifts, ensuring the validity of the generalized second law of thermodynamics. Correspondingly, $dot{S}_{mathrm{tot}} > 0$ throughout, while $ddot{S}_{mathrm{tot}} arXiv:2604.18723v1 Announce Type: new
Abstract: We perform a model-independent investigation of the thermodynamic evolution of the Universe by reconstructing the expansion history from observational data using Gaussian Process regression. We consider three independent combinations of datasets, namely CC32+DESI DR2+Pantheon+, CC32+DESI DR2+Union3, and CC32+DESI DR2+DES Y5, allowing us to assess the impact of different supernova samples on the reconstruction. From the reconstructed Hubble parameter and its derivatives over the redshift range 0 to 2, we evaluate key thermodynamic quantities associated with the apparent horizon, including the diagnostic function $P(z)$, the entropy production rate $dot{S}_{mathrm{tot}}$, and its second derivative $ddot{S}_{mathrm{tot}}$. We find that $P(z)$ remains positive across all redshifts, ensuring the validity of the generalized second law of thermodynamics. Correspondingly, $dot{S}_{mathrm{tot}} > 0$ throughout, while $ddot{S}_{mathrm{tot}}