Galaxy clusters are the vast and massive gravitationally bound structures in the Universe and are often considered as the largest reservoirs of high-energy cosmic-ray particles. However, no direct and conclusive detection of $\gamma$ rays from them has been reported to date. This would mean either our understanding of these systems is insufficient or it could be due to the limited sensitivity and poor localization capabilities of $\gamma$-ray telescopes. Moreover, strong interactions of $\gamma$ rays with intergalactic material along the line of sight allow detectable signals from only a few very nearby clusters. The detection prospects are further constrained to dynamically active clusters, which are theoretically expected to produce detectable $\gamma$-ray emissions. Given these constraints, we systematically shortlisted a suitable sample of nearby ($z<0.05$), dynamically active galaxy clusters and performed a comprehensive analysis of 14 years of Fermi-LAT data. In this work, we present a detailed study of diffuse $\gamma$-ray emission around one such galaxy cluster, Abell 119 (A119). Known for its ongoing merger activity, A119 exhibits significant x-ray luminosity and complex dynamical activity. We analyzed the data using the fermipy package and Fermi Science Tools for spatial and spectral models to account for all potential sources of $\gamma$-ray emission. Our analysis confirms all the Fourth Fermi Gamma-ray LAT (Large Area Telescope) (4FGL) point sources $4\mathrm{FGLJ}0059.3-0152$, $4\mathrm{FGLJ}0101.0-0059$, and $4\mathrm{FGLJ}0059.2+0006$ with significant test statistic values. It further reveals a $\sim 4\sigma$ excess of diffuse $\gamma$-ray emission, offset by $\sim 0.25°$ from the cluster center—suggesting a possible association with the cluster halo region. The extended model provides the most robust description for the detected $\gamma$-ray excess. The computed luminosity bounds for the extended models $\sim 12.21_{-3.95}^{+2.74}\times {10}^{42}\mathrm{erg}{\mathrm{s}}^{-1}$ and the particle spectrum $\sim 2.25_{-0.13}^{+0.38}$ are consistent with previous studies and provide further evidence for the presence of diffuse gamma rays in this galaxy cluster. With the available information, we conclude that the observed emission may arise from nonthermal processes in the intracluster medium, most likely hadronic process. Although the observed $\sim 4\sigma$ signal is significant, uncertainties in source localization and other parameters and instrumental limitations prevent us from confirming the detection. Nonetheless, our results underscore the potential for deeper exploration of $\gamma$ rays in the cluster environment with improved sensitivity and resolution. Moreover, an estimated neutrino flux $E^2{\varphi }_{\nu }\approx 3\times {10}^{-10}\mathrm{GeV}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}{\mathrm{sr}}^{-1}$ telescope provides motivation for future observations with upcoming neutrino telescopes.

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• Cosmic ray acceleration
• Cosmic ray composition & spectra
• Cosmic ray propagation
• Cosmic ray sources
• Cosmic rays & astroparticles
• Gamma ray astronomy
• Large scale structure of the Universe
• Sky surveys
• Electromagnetic radiation astronomy