We present a general relativistic ( GR ) model of jet variability in active galactic nuclei due to orbiting blobs in helical motion along a funnel or cone shaped magnetic surface anchored to the accretion disk near the black hole .
Considering a radiation pressure driven flow in the inner region , we find that it stabilizes the flow , yielding Lorentz factors ranging between 1.1 and 7 at small radii for reasonable initial conditions .
Assuming these as inputs , simulated light curves ( LCs ) for the funnel model include Doppler and gravitational shifts , aberration , light bending , and time delay .
These LCs are studied for quasi-periodic oscillations ( QPOs ) and the power spectral density ( PSD ) shape and yield an increased amplitude ( \sim 12 % ) ; a beamed portion and a systematic phase shift with respect to that from a previous special relativistic model .
The results strongly justify implementing a realistic magnetic surface geometry in Schwarzschild geometry to describe effects on emission from orbital features in the jet close to the horizon radius .
A power law shaped PSD with a typical slope of -2 and QPOs with timescales in the range of ( 1.37 - 130.7 ) days consistent with optical variability in Blazars , emerges from the simulations for black hole masses M _ { \bullet } = ( 0.5 - 5 ) \times 10 ^ { 8 } M _ { \odot } and initial Lorentz factors \gamma _ { jet,i } = 2 - 10 .
The models presented here can be applied to explain radio , optical , and X-ray variability from a range of jetted sources including active galactic nuclei , X-ray binaries and neutron stars .