The eccentricity enhancement effect of intermediate-mass-ratio-inspirals: dark matter and black hole mass

It was found that dark matter (DM) in an intermediate-mass-ratio-inspiral (IMRI) system has a significant enhancement effect on the orbital eccentricity of a stellar massive compact object, such as a black hole (BH), which may be tested by space-based gravitational wave (GW) detectors, including LISA, Taiji, and Tianqin in future observations. In this paper, we study the enhancement effect of the eccentricity for an IMRI under different DM density profiles and center BH masses. Our results are as follows: (1) in terms of the general DM spike distribution, the enhancement of the eccentricity is basically consistent with the power-law profile, which indicates that it is reasonable to adopt the power-law profile; (2) in the presence of a DM spike, the different masses of the center BH will affect the eccentricity, which provides a new way for us to detect the BH's mass; and (3) considering the change in the eccentricity in the presence and absence of a DM spike, we find that it is possible to distinguish DM models by measuring the eccentricity at a scale of approximately 10(5)GM/c(2).

Automated summary

This study reveals a significant enhancement effect of dark matter on the orbital eccentricity of a black hole in an intermediate-mass-ratio-inspiral (IMRI) system, which can be detected by future space-based gravitational wave detectors. The study also shows that different densities of dark matter and masses of center black holes can influence the eccentricity of the system, providing new insights for detecting black hole mass. Furthermore, the research suggests that it is possible to differentiate dark matter models by measuring the eccentricity at a certain scale.