Effect of gravitational radiation reaction on nonequatorial orbits around a Kerr black hole

The effect of gravitational radiation reaction on orbits around a spinning\nblack hole is analyzed. Such orbits possess three constants of motion: $\\iota$,\n$e$, and $a$, which correspond, in the Newtonian limit of the orbit being an\nellipse, to the inclination angle of the orbital plane to the hole's equatorial\nplane, the eccentricity, and the semi-major axis length, respectively. First,\nit is argued that circular orbits ($e=0$) remain circular under gravitational\nradiation reaction. Second, for elliptical orbits (removing the restriction of\n$e=0$), the evolution of $\\iota$, $e$, and $a$ is computed to leading order in\n$S$ (the magnitude of the spin angular momentum of the hole) and in $M/a$,\nwhere $M$ is the mass of the black hole. As $a$ decreases, $\\iota$ increases\nand $e$ decreases.\n