Blandford-Znajek Effect and Neutrino Pair Annihilation as the Central Engines of Gamma Ray Bursts and Blazars

The central engine of gamma-ray burst is considered. Blandford-Znajek (BZ) process is reconsidered under the asymtotic magnetic condition $\mathbf{B}=B_0\widehat{z}$ (rotation axis) at $r\gg r_H$. Another scenario of $\nu \bar{\nu }\to e^{+}{e}^{-}$ driven jet are combined to BZ process to compliment it.