10 research outputs found
Gravitational wave snapshots of generic extreme mass ratio inspirals
Using black hole perturbation theory, we calculate the gravitational waves
produced by test particles moving on bound geodesic orbits about rotating black
holes. The orbits we consider are generic - simultaneously eccentric and
inclined. The waves can be described as having radial, polar, and azimuthal
"voices", each of which can be made to dominate by varying eccentricity and
inclination. Although each voice is generally apparent in the waveform, the
radial voice is prone to overpowering the others. We also compute the radiative
fluxes of energy and axial angular momentum at infinity and through the event
horizon. These fluxes, coupled to a prescription for the radiative evolution of
the Carter constant, will be used in future work to adiabatically evolve
through a sequence of generic orbits. This will enable the calculation of
inspiral waveforms that, while lacking certain important features, will
approximate those expected from astrophysical extreme mass ratio captures
sufficiently well to aid development of measurement algorithms on a relatively
short timescale.Comment: Minor changes in response to comments from readers, referees, and
editors. Final version, as it will appear in Physical Review D. Raw data and
a small program which will convert the data into waveforms lasting for
arbitrary lengths of time can be found at
http://gmunu.mit.edu/sdrasco/snapshot
Extreme Mass Ratio Inspirals: LISA's unique probe of black hole gravity
In this review article I attempt to summarise past and present-ongoing-work
on the problem of the inspiral of a small body in the gravitational field of a
much more massive Kerr black hole. Such extreme mass ratio systems, expected to
occur in galactic nuclei, will constitute prime sources of gravitational
radiation for the future LISA gravitational radiation detector. The article's
main goal is to provide a survey of basic celestial mechanics in Kerr spacetime
and calculations of gravitational waveforms and backreaction on the small
body's orbital motion, based on the traditional `flux-balance' method and the
Teukolsky black hole perturbation formalism.Comment: Invited review article, 45 pages, 23 figure
A Toy Model for Testing Finite Element Methods to Simulate Extreme-Mass-Ratio Binary Systems
Extreme mass ratio binary systems, binaries involving stellar mass objects
orbiting massive black holes, are considered to be a primary source of
gravitational radiation to be detected by the space-based interferometer LISA.
The numerical modelling of these binary systems is extremely challenging
because the scales involved expand over several orders of magnitude. One needs
to handle large wavelength scales comparable to the size of the massive black
hole and, at the same time, to resolve the scales in the vicinity of the small
companion where radiation reaction effects play a crucial role. Adaptive finite
element methods, in which quantitative control of errors is achieved
automatically by finite element mesh adaptivity based on posteriori error
estimation, are a natural choice that has great potential for achieving the
high level of adaptivity required in these simulations. To demonstrate this, we
present the results of simulations of a toy model, consisting of a point-like
source orbiting a black hole under the action of a scalar gravitational field.Comment: 29 pages, 37 figures. RevTeX 4.0. Minor changes to match the
published versio
Research Update on Extreme-Mass-Ratio Inspirals
The inspirals of stellar-mass mass compact objects into massive black holes
in the centres of galaxies are one of the most important sources of
gravitational radiation for space-based detectors like LISA or eLISA. These
extreme-mass-ratio inspirals (EMRIs) will enable an ambitious research program
with implications for astrophysics, cosmology, and fundamental physics. This
article is a summary of the talks delivered at the plenary session on EMRIs at
the 10th International LISA Symposium. It contains research updates on the
following topics: astrophysics of EMRIs; EMRI science potential; and EMRI
modeling.Comment: 17 pages, no figures. Proceedings of the LISA Symposium X, to be
published at the Journal of Physic
Intermediate and extreme mass-ratio inspirals — astrophysics, science applications and detection using LISA
Black hole binaries with extreme (gtrsim104:1) or intermediate (~102–104:1) mass ratios are among the most interesting gravitational wave sources that are expected to be detected by the proposed laser interferometer space antenna (LISA). These sources have the potential to tell us much about astrophysics, but are also of unique importance for testing aspects of the general theory of relativity in the strong field regime. Here we discuss these sources from the perspectives of astrophysics, data analysis and applications to testing general relativity, providing both a description of the current state of knowledge and an outline of some of the outstanding questions that still need to be addressed. This review grew out of discussions at a workshop in September 2006 hosted by the Albert Einstein Institute in Golm, Germany
Self-force: Computational Strategies
Building on substantial foundational progress in understanding the effect of
a small body's self-field on its own motion, the past 15 years has seen the
emergence of several strategies for explicitly computing self-field corrections
to the equations of motion of a small, point-like charge. These approaches
broadly fall into three categories: (i) mode-sum regularization, (ii) effective
source approaches and (iii) worldline convolution methods. This paper reviews
the various approaches and gives details of how each one is implemented in
practice, highlighting some of the key features in each case.Comment: Synchronized with final published version. Review to appear in
"Equations of Motion in Relativistic Gravity", published as part of the
Springer "Fundamental Theories of Physics" series. D. Puetzfeld et al.
(eds.), Equations of Motion in Relativistic Gravity, Fundamental Theories of
Physics 179, Springer, 201
Testing General Relativity with Low-Frequency, Space-Based Gravitational-Wave Detectors
We review the tests of general relativity that will become possible with space-based gravitational-wave detectors operating in the ∼ 10^{-5} – 1 Hz low-frequency band. The fundamental aspects of gravitation that can be tested include the presence of additional gravitational fields other than the metric; the number and tensorial nature of gravitational-wave polarization states; the velocity of propagation of gravitational waves; the binding energy and gravitational-wave radiation of binaries, and therefore the time evolution of binary inspirals; the strength and shape of the waves emitted from binary mergers and ringdowns; the true nature of astrophysical black holes; and much more. The strength of this science alone calls for the swift implementation of a space-based detector; the remarkable richness of astrophysics, astronomy, and cosmology in the low-frequency gravitational-wave band make the case even stronger