Extreme mass-ratio inspiral around the horizonless massive object
Tieguang Zi (School of Physics and Optoelectronics, South China University of Technology, Guangzhou, 510641, People’s Republic of China); Liangliang Ren (School Electrical and Electronic Engineering, Anhui Science and Technology University, Bengbu, Anhui, 233030, China); Jun Cheng (College of Mathematics and Physics, Hunan University of Arts and Science, Changde, 415000, People’s Republic of China, Hunan Province Key Laboratory of Photoelectric Information Integration and Optical Manufacturing Technology, Changde, 415000, People’s Republic of China)
In this paper, we calculated the extreme mass-ratio inspiral (EMRI) waveform radiated from a binary composed of a massive horizonless object (MHO) and a compact object (CO), where CO is spiraling on a circular equatorial orbit around the MHO. Due to the absent of horizon, there exist the ingoing and outgoing waves near the reflective surface of MHO, which have significantly influence on the evolution of orbital parameters. We observe that there indeed exist the differences of EMRI trajectories between the massive Kerr black hole and MHO cases. By calculating the mismatch of gravitational wave (GW) waveforms from massive black hole (MBH) and MHO, our result indicates that the space-borne gravitational wave detector could distinguish the modified effect of reflectivities from the BH case, which allows to put an upper constraint on the reflectivity $${\mathcal {R}}$$ of MHO, at the level of $${\mathcal {R}} > rsim 10^{-4}$$ .
