arXiv subjects

Mazaharul Abedin

Publications and source records attributed to Mazaharul Abedin.

2 recordsLinked to original sources

arXiv2025

When Dark Matter Heats Up: A Model-Independent Search for Non-Cold Behavior

This article questions the common assumption of cold dark matter (DM) by exploring the possibility of a non-zero equation of state (EoS) without relying on any parametric approach. In standard cosmological analyses, DM is typically modeled as pressureless dust with $w_{\rm DM} = 0$, an assumption that aligns with large-scale structure formation, supports the empirical success of the $Λ$CDM model, and simplifies cosmological modeling. However, there is no fundamental reason to exclude a non-zero $w_{\rm DM}$ from the cosmological framework. In this work, we explore this possibility through non-parametric and parametric reconstructions based on Gaussian Process Regression. The reconstructions use Hubble parameter measurements from Cosmic Chronometers (CC), the Pantheon+ sample of Type Ia supernovae, and Baryon Acoustic Oscillation (BAO) data from DESI DR1 and DR2. Our findings suggest that a dynamical EoS for DM, although only mildly supported statistically, cannot be conclusively ruled out. Notably, we observe a mild tendency ($\sim 1σ$) toward a negative $w_{\rm DM}$ at the present epoch, which is most likely due to inconsistencies between the BAO data from DESI and other datasets.

astro-ph.CO↗

arXiv2025

In search of an interaction in the dark sector through Gaussian Process and ANN approaches

Whether the current observational data indicate any evidence of interaction between the dark sector is a matter of supreme interest at the present moment. This article searched for an interaction in the dark sector between a pressure-less dark matter and a dark energy fluid with constant equation of state, $w_{\rm DE}$. For this purpose, two non-parametric approaches, namely, the Gaussian Process (GP) and the Artificial Neural Networks (ANN) have been employed and using the Hubble data from Cosmic Chronometers (CC), Pantheon+ from Supernovae Type Ia and their combination we have reconstructed the interaction function. We find that for $w_{\rm DE} =-1$, the interaction in the dark sector is not prominent while for $w_{\rm DE} \neq -1$, evidence of interaction is found depending on the value of $w_{\rm DE}$. In particularly, we find that if we start deviating from $w_{\rm DE} = -1$ either in the quintessence ($w_{\rm DE} > -1$) or phantom ($w_{\rm DE} < -1$) direction, an emergence of dark interaction is observed from both GP and ANN reconstructions. We further note that ANN which is applied for the first time in this context seems to play a very efficient role compared to GP.

astro-ph.CO↗