Study of Neutrino dominated accretion flow (NDAF) around a rotating black hole (BH)

We study the properties of the neutrino dominated accretion flow (NDAF) around a rotating black hole (BH). This type of accretion flow involves a hyper-accretion rate ($\dot{M} \sim 0.001-10$ $M_\odot~{\rm s}^{-1}$), causing the disk to become optically thick for photons. As a result, it becomes difficult for photons to escape. However, neutrinos can easily move out of the disk, leading to the cooling of the flow through radiative emissions and annihilation processes. By considering the neutrino emission process, we self-consistently solve the governing equations to obtain the global transonic shocked accretion solutions for NDAF. We calculate the neutrino luminosity ($L_{\rm{\nu}}$) and the neutrino annihilation luminosity ($L_{\nu \, \bar{\nu}}$) for shocked accretion solutions. We have observed that flow parameters such as specific energy ($\varepsilon$) and angular momentum ($\lambda$) significantly influence $L_{\nu \, \bar{\nu}}$. By comparing $L_{\nu \, \bar{\nu}}$ with the observed output power ($\dot{E}$) of Gamma-Ray Burst (GRBs) sources, we have found a good agreement. Finally, we have explored our solutions to constrain the spin parameter ($a_{\rm k}$) of a central black hole.