1,779 research outputs found
Ready-to-use post-Newtonian gravitational waveforms for binary black holes with non-precessing spins: An update
For black-hole binaries whose spins are (anti-) aligned with respect to the
orbital angular momentum of the binary, we compute the frequency domain phasing
coefficients including the quadratic-in-spin terms up to the third
post-Newtonian (3PN) order, the cubic-in-spin terms at the leading order,
3.5PN, and the spin-orbit effects up to the 4PN order. In addition, we obtain
the 2PN spin contributions to the amplitude of the frequency-domain
gravitational waveforms for non-precessing binaries, using recently derived
expressions for the time-domain polarization amplitudes of binaries with
generic spins, complete at that accuracy level. These two results are updates
to Arun et al. (2009) [1] for amplitude and Wade et al. (2013) [2] for phasing.
They should be useful to construct banks of templates that model accurately
non-precessing inspiraling binaries, for parameter estimation studies, and or
constructing analytical template families that accounts for the
inspiral-merger-ringdown phases of the binary.Comment: 8 pages, an additional file (readable in MATHEMATICA) containing all
the key results included in the sourc
Stability of a horizontal viscous fluid layer in a vertical time periodic electric field
The stability of a horizontal interface between two viscous fluids, one of
which is conducting and the other is dielectric, acted upon by a vertical
time-periodic electric field is considered. The two fluids are bounded by
electrodes separated by a finite distance. By means of Floquet theory, the
marginal stability curves are obtained, thereby elucidating the dependency of
the critical voltage and wavenumber upon the fluid viscosities. The limit of
vanishing viscosities is shown to be in excellent agreement with the marginal
stability curves predicted by means of a Mathieu equation. The methodology to
obtain the marginal stability curves developed here is applicable to any
arbitrary but time periodic-signal, as demonstrated for the case of a signal
with two different frequencies. As a special case, the marginal stability
curves for an applied ac voltage biased by a dc voltage are depicted. It is
shown that the mode coupling caused by the normal stress at the interface due
to the electric field leads to appearance of harmonic modes and subharmonic
modes. This is in contrast to the application of a voltage with a single
frequency which always leads to a harmonic mode. Whether a harmonic or
subharmonic mode is the most unstable one depends on details of the excitation
signal. It is also shown that the electrode spacing has a distinct effect on
the stability bahavior of the system
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