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Extreme mass ratio inspirais (EMRIs), the inspirais of compact objects into supermassive black holes, are important gravitational wave sources for the Laser Interferometer Space Antenna (LISA). We study the performance of various post-Newtonian (PN) template families relative to the waveforms that are high-precision numerical solutions of the Teukolsky equation in the context of EMRI parameter estimation with LISA. Expressions for the time-domain waveforms TaylorTl, TaylorT2, TaylorT3, TaylorT4 and TaylorEt are derived up to 22 PN order, i.e. O(ν44) (v is the characteristic velocity of the binary) beyond the Newtonian term, for a test particle in a circular orbit around a Schwarzschild black hole. The phase difference between the above 22 PN waveform families and numerical waveforms are evaluated during two-year inspirais for two prototypical EMRI systems with mass ratios 10-4 and 10-5. We find that the déphasés (in radians) for TaylorTl and TaylorT2, respectively, are about 10-9 (10-2) and 10-9 (10-3) for mass ratio 10-4 (10-5). This suggests that using 22 PN TaylorTl or TaylorT2 waveforms for parameter estimation of EMRIs will result in accuracies comparable to numerical waveform accuracy for most of the LISA parameter space. On the other hand, from the dephase results, we find that TaylorT3, TaylorT4 and TaylorEt fare relatively poorly as one approaches the last stable orbit. This implies that, as for comparable mass binaries using the 3.5 PN phase of waveforms, the 22 PN TaylorT3 and TaylorEt approximants do not perform well enough for the EMRIs. The reason underlying the poor performance of TaylorT3, TaylorT4 and TaylorEt relative to TaylorTl and TaylorT2 is finally examined. [ABSTRACT FROM AUTHOR]

The accurate calculation of the long-term phase evolution of gravitational wave (GW) forms from extreme (intermediate) mass-ratio inspirals [E(I)MRIs] is an inevitable step to extract information from this system. In order to achieve this goal, it is believed that we need to understand the gravitational self- forces. However, it has not been quantitatively demonstrated that the second-order self-forces are necessary for this purpose. In this paper, we revisit the problem to estimate the order of magnitude of the dephasing caused by the second-order self-forces on a small body in a quasicircular orbit around a Kerr black hole, based on the knowledge of the post-Newtonian (PN) approximation and invoking the energy balance argument. In particular, we focus on the averaged dissipative part of the self-force, since it gives the leading-order contribution among their various components. To avoid the possibility of the energy flux of GWs becoming negative, we propose a new simple resummation called exponential resummation, which assures the positivity of the energy flux. In order to estimate the magnitude of the yet-unknown second-order self-forces, here we point out the scaling property in the absolute value of the PN coefficients of the energy flux. Using these new tools, we evaluate the expected magnitude of dephasing. Our analysis indicates that the dephasing due to the second-order self-forces for quasicircular E(I)MRIs may be well captured by the 3 PN energy flux, once we obtain all the spin-dependent terms, except for the case with an extremely large spin of the central Kerr black hole. [ABSTRACT FROM AUTHOR]

Ultralight degrees of freedom coupled to matter lead to resonances, which can be excited when the Compton wavelength of the field equals a dynamical scale in the problem. For binaries composed of a star orbiting a supermassive black hole, these resonances lead to a smoking-gun effect: a periastron distance which stalls, even in the presence of gravitational-wave dissipation. This effect, also called a floating orbit, occurs for generic equatorial but eccentric orbits, and we argue that finite-size effects are not enough to suppress it. [ABSTRACT FROM AUTHOR]

Extreme mass ratio inspirals (EMRIs), the inspirals of compact objects into supermassive black holes, are important gravitational wave sources for the Laser Interferometer Space Antenna (LISA). We study the performance of various post-Newtonian (PN) template families relative to the waveforms that are high-precision numerical solutions of the Teukolsky equation in the context of EMRI parameter estimation with LISA. Expressions for the time-domain waveforms TaylorT1, TaylorT2, TaylorT3, TaylorT4 and TaylorEt are derived up to 22 PN order, i.e. O(v44) (v is the characteristic velocity of the binary) beyond the Newtonian term, for a test particle in a circular orbit around a Schwarzschild black hole. The phase difference between the above 22 PN waveform families and numerical waveforms are evaluated during two-year inspirals for two prototypical EMRI systems with mass ratios 10-4 and 10-5. We find that the dephases (in radians) for TaylorT1 and TaylorT2, respectively, are about 10-9 (10-2) and 10-9 (10-3) for mass ratio 10-4 (10-5). This suggests that using 22 PN TaylorT1 or TaylorT2 waveforms for parameter estimation of EMRIs will result in accuracies comparable to numerical waveform accuracy for most of the LISA parameter space. On the other hand, from the dephase results, we find that TaylorT3, TaylorT4 and TaylorEt fare relatively poorly as one approaches the last stable orbit. This implies that, as for comparable mass binaries using the 3.5 PN phase of waveforms, the 22 PN TaylorT3 and TaylorEt approximants do not perform well enough for the EMRIs. The reason underlying the poor performance of TaylorT3, TaylorT4 and TaylorEt relative to TaylorT1 and TaylorT2 is finally examined. [ABSTRACT FROM AUTHOR]

We generalize the factorized resummation of multipolar waveforms introduced by Damour, Iyer, and Nagar to spinning black holes. For a nonspinning test particle spiraling a Kerr black hole in the equatorial plane, we find that factorized multipolar amplitudes which replace the residual relativistic amplitude fℓm with its ℓth root, ρℓm=fℓm1/ℓ, agree quite well with the numerical amplitudes up to the Kerr-spin value q≤0.95 for orbital velocities v≤0.4. The numerical amplitudes are computed solving the Teukolsky equation with a spectral code. The agreement for prograde orbits and large spin values of the Kerr black-hole can be further improved at high velocities by properly factoring out the lower-order post-Newtonian contributions in ρℓm. The resummation procedure results in a better and systematic agreement between numerical and analytical amplitudes (and energy fluxes) than standard Taylor-expanded post-Newtonian approximants. This is particularly true for higher-order modes, such as (2,1), (3,3), (3,2), and (4,4), for which less spin post-Newtonian terms are known. We also extend the factorized resummation of multipolar amplitudes to generic mass-ratio, nonprecessing, spinning black holes. Lastly, in our study we employ new, recently computed, higher-order post-Newtonian terms in several subdominant modes and compute explicit expressions for the half and one-and-half post-Newtonian contributions to the odd-parity (current) and even-parity (odd) multipoles, respectively. Those results can be used to build more accurate templates for ground-based and space-based gravitational-wave detectors. [ABSTRACT FROM AUTHOR]