1,435 research outputs found
Gravitational reaction force on a particle in the Schwarzschild background
We formulate a new method to calculate the gravitational reaction force on a
particle of mass orbiting a massive black hole of mass . In this
formalism, the tail part of the retarded Green function, which is responsible
for the reaction force, is calculated at the level of the Teukolsky equation.
Our method naturally allows a systematic post-Minkowskian (PM) expansion of the
tail part at short distances. As a first step, we consider the case of a
Schwarzschild black hole and explicitly calculate the first post-Newtonian
(1PN) tail part of the Green function. There are, however, a couple of issues
to be resolved before explicitly evaluating the reaction force by applying the
present method. We discuss possible resolutions of these issues.Comment: 15 pages, no figure, submitted to Prog. Theor. Phy
How close can we approach the event horizon of the Kerr black hole from the detection of the gravitational quasinormal modes?
Using the WKB method, we show that the peak location () of the
potential, which determines the quasinormal mode frequency of the Kerr black
hole, obeys an accurate empirical relation as a function of the specific
angular momentum and the gravitational mass . If the quasinormal mode
with is observed by gravitational wave detectors, we can confirm
the black-hole space-time around the event horizon, where is the event horizon radius. While if the
quasinormal mode is different from that of general relativity, we are forced to
seek the true theory of gravity and/or face to the existence of the naked
singularity.Comment: 8 pages, 4 figure
Post-Newtonian templates for binary black-hole inspirals: the effect of the horizon fluxes and the secular change in the black-hole masses and spins
Black holes (BHs) in an inspiraling compact binary system absorb the
gravitational-wave (GW) energy and angular-momentum fluxes across their event
horizons and this leads to the secular change in their masses and spins during
the inspiral phase. The goal of this paper is to present ready-to-use, 3.5
post-Newtonian (PN) template families for spinning, non-precessing, binary BH
inspirals in quasicircular orbits, including the 2.5PN and 3.5PN horizon flux
contributions as well as the correction due to the secular change in the BH
masses and spins through 3.5PN order, respectively, in phase. We show that, for
binary BHs observable by Advanced LIGO with high mass ratio (larger than ~10)
and large aligned-spins (larger than ~0.7), the mismatch between the
frequency-domain template with and without the horizon-flux contribution is
typically above the 3% mark. For (supermassive) binary BHs observed by LISA,
even a moderate mass-ratios and spins can produce a similar level of the
mismatch. Meanwhile, the mismatch due to the secular time variations of the BH
masses and spins is well below the 1% mark in both cases, hence this is truly
negligible. We also point out that neglecting the cubic-in-spin, point-particle
phase term at 3.5PN order would deteriorate the effect of BH absorption in the
template.Comment: v3: 50 pages, 8 figures, matches the published versio
Possible confirmation of the existence of ergoregion by the Kerr quasinormal mode in gravitational waves from Pop III massive black hole binary
The existence of the ergoregion of the Kerr space-time has not been confirmed
observationally yet. We show that the confirmation would be possible by
observing the quasinormal mode in gravitational waves. As an example, using the
recent population synthesis results of Pop III binary black holes, we find that
the peak of the final merger mass () is about , while
the fraction of the final spin needed for the
confirmation of a part of ergoregion is . To confirm the frequency
of the quasinormal mode, is needed. The standard model of Pop
III population synthesis tells us that the event rate for the confirmation of
more than of the ergoregion by the second generation gravitational wave
detectors is where and
are the peak value of the Pop III star formation rate and the
fraction of binaries, respectively.Comment: Accepted for publication in PTEP. Comments welcom
Gravitational wave quasinormal mode from Population III massive black hole binaries in various models of population synthesis
Focusing on the remnant black holes after merging binary black holes, we show
that ringdown gravitational waves of Population III binary black holes mergers
can be detected with the rate of
for various parameters and functions. This rate is estimated for the events
with SNR for the second generation gravitational wave detectors such as
KAGRA. Here, and are the peak value of the Population
III star formation rate and the fraction of binaries, respectively. When we
consider only the events with SNR, the event rate becomes . This suggest that for remnant black hole's spin
we have the event rate with SNR less than , while it is for the third generation detectors such as Einstein
Telescope. If we detect many Population III binary black holes merger, it may
be possible to constrain the Population III binary evolution paths not only by
the mass distribution but also by the spin distribution.Comment: Submitted to PTEP. comments welcom
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