Radiation hydrodynamic radial oscillations: General relativistic treatment

Diverse luminosity variabilities exist in many accretion systems like galactic X-ray sources. Quasi-periodic oscillation (QPO) in luminosity is one example seen in low-mass X-ray binaries. To extend the work of Miller and Park[1] who investigated the radiation hydrodynamic instability with Newtonian approximation as the driving mechanism for the horizontal and flaring branch QPOs, we study the stability of the radiation dominated spherical accretion flow to radial perturbations in the framework of general relativity. Effects of curved spacetime and radiation moments in the fixed and comoving frames are rigorously treated. Both local and global modes are found through linear analyses and the result is compared with those of previous works.