arXiv subjects

Tieguang Zi

Publications and source records attributed to Tieguang Zi.

21 records · Page 2Linked to original sources

arXiv2023

Gravitational waves from extreme mass ratio inspirals around a hairy Kerr black hole

Recently, Contreras et al. \cite{Contreras:2021yxe} introduced a new type of black hole, called hairy Kerr black hole (HKBH), which describes a Kerr BH surrounded by an axially symmetric fluid with conserved energy momentum tensor. In this paper, we compute the gravitational waves emitted from the extreme mass ratio inspirals around the HKBHs. We solve the Dudley-Finley equation, which describes the gravitational perturbations of the HKBH, and obtain the energy fluxes induced by a stellar-mass compact object moving on the equatorial, circular orbits. Using the adiabatic approximation, we evolved the radii of the circular orbits by taking into account the backreaction of gravitational radiation. Then we calculate the dephasing and mismatch of the EMRI waveforms from the HKBH and Kerr BH to assess the difference between them. The results demonstrate that the EMRI waveforms from the HKBH with deviation parameter larger than $0.001$ and hair charge smaller than $1.5M$ can be discerned by LISA.

gr-qc↗

arXiv2023

Probing the Tidal Deformability of the Central Object in an Extreme Mass Ratio Inspiral with Analytic Kludge Waveforms

We develop approximate ``analytic-kludge" waveforms to describe the inspiral of a stellar-mass compact object into a supermassive compact object in an extreme mass ratio inspiral (EMRI) scenario. The deformability of the supermassive compact object is characterized by a dimensionless quantity called the tidal Love number (TLN). Our analysis shows that, up to the leading order of the mass ratio, the conservative dynamics of the EMRI are not affected by tidal interaction, and the tidal effect is only present in the induced quadrupole moment. We calculate the energy and angular momentum fluxes and obtain leading order corrections to the orbital evolution equations. By comparing the waveforms with and without tidal interaction, we demonstrate that even a small TLN can produce significant differences in the waveforms, which can be detected by space-borne detector LISA. Finally, using the Fisher information matrix method, we perform parameter estimation for the TLN and find that the precision can reach the level of $10^{-4}$ in suitable scenarios.

gr-qc↗

arXiv2023

Analytic Kludge Waveforms for Extreme Mass Ratio Inspirals of Charged Object around Kerr-Newman Black Hole

We derive the approximate, ``analytic-kludge'' (AK) waveforms for the inspiral of a charged stellar-mass compact object (CO) into a charged massive Kerr-Newman (KN) black hole (BH). The modifications of the inspiral orbit due to the charges in this system can be attributed to three sources: the electric force between the CO and the MBH, the energy flow of the dipole electromagnetic radiation, and the deformation of the metric caused by the charge of the MBH. All these are encoded explicitly in the fundamental frequencies of the orbits, which are calculated analytically in the weak-field regime. By calculating the mismatch between the waveforms for charged and neutral EMRI systems with respect to space-borne detectors TianQin and LISA, we show that tiny charges in the system can produce distinct imprints on the waveforms. Finally, we perform parameter estimation for the charges using the Fisher information matrix method and find that the precision can reach the level of $10^{-5}$ in suitable scenarios. We also study the effects of charges on the parameter estimation of charge, where the effects from the charge of the MBH can be well explained by its effects on the cutoff of the inspiral.

gr-qc↗