Gravitational Radiations from a Spinning Compact Object around a supermassive Kerr black hole in circular orbit

TL;DR

This paper investigates how the spin of a small compact object affects gravitational wave emissions and energy fluxes in circular orbits around a supermassive Kerr black hole, highlighting the importance of spin in waveform modeling.

Contribution

It provides a detailed analysis of the influence of the small body's spin on energy fluxes and waveform phase evolution in Kerr spacetime, emphasizing the need to include spin effects in gravitational wave templates.

Findings

Positive spin decreases energy fluxes to infinity.

Negative spin increases energy fluxes to infinity.

Spin effects on fluxes resemble quadratic functions.

Abstract

The gravitational waves and energy radiations from a spinning compact object with stellar mass in a circular orbit in the equatorial plane of a supermassive Kerr black hole are investigated in this paper. The effect how the spin acts on energy and angular moment fluxes is discussed in detail. The calculation results indicate that the spin of small body should be considered in waveform-template production for the upcoming gravitational wave detections. It is clear that when the direction of spin axes is the same as the orbitally angular momentum ("positive" spin), spin can decrease the energy fluxes which radiate to infinity. For antidirection spin ("negative"), the energy fluxes to infinity can be enlarged. And the relations between fluxes (both infinity and horizon) and spin look like quadratic functions. From frequency shift due to spin, we estimate the wave-phase accumulation during the inspiraling process of the particle. We find that the time of particle inspiral into the black hole is longer for positive spin and shorter for negative compared with the nonspinning particle. Especially, for extreme spin value, the energy radiation near the horizon of the extreme Kerr black hole is much more than that for the nonspinning one. And consequently, the maximum binging energy of the extreme spinning particle is much larger than that of the nonspinning particle.