  Blazars, a class of highly variable active galactic nuclei, sometimes exhibit
Orphan $\gamma$-ray flares. These flares having high flux only in $\gamma$-ray
energies do not show significant variations in flux at lower energies. We study
the temporal and spectral profile of these Orphan $\gamma$-ray flares in detail
from three $\gamma-ray$ bright blazars, 3C 273, PKS 1510-089 and 3C 279 and
also their simultaneous broadband emissions. We find that the variability
timescales of the Orphan $\gamma$-ray flares were $(0.96\pm0.28)$ days,
$(3.12\pm2.40)$ hr and $(2.16\pm0.72)$ hr, for 3C 273, PKS 1510-089 and 3C 279,
respectively. The broadband spectral energy distributions (SEDs) during these
flares have been modelled with a leptonic model from two emission regions. This
model suggests that Orphan $\gamma$-ray flares might have originated from
inverse Compton scattering of relativistic electrons by the seed photons from
the broad-line region or dusty torus, which is the first region. While the
second broader region, lying further down the jet, could be responsible for
X-ray and radio emissions. The possible locations of these emission regions in
the jets of the three sources have been estimated from SED modelling.

High Energy Astrophysical Phenomena