51 research outputs found
Localizing merging black holes with sub-arcsecond precision using gravitational-wave lensing
The current gravitational-wave localization methods rely mainly on sources
with electromagnetic counterparts. Unfortunately, a binary black hole does not
emit light. Due to this, it is generally not possible to localize these objects
precisely. However, strongly lensed gravitational waves, which are forecasted
in this decade, could allow us to localize the binary by locating its lensed
host galaxy. Identifying the correct host galaxy is challenging because there
are hundreds to thousands of other lensed galaxies within the sky area spanned
by the gravitational-wave observation. However, we can constrain the lensing
galaxy's physical properties through both gravitational-wave and
electromagnetic observations. We show that these simultaneous constraints allow
one to localize quadruply lensed waves to one or at most a few galaxies with
the LIGO/Virgo/Kagra network in typical scenarios. Once we identify the host,
we can localize the binary to two sub-arcsec regions within the host galaxy.
Moreover, we demonstrate how to use the system to measure the Hubble constant
as a proof-of-principle application.Comment: 5 pages (main text) + 5 pages (methods+references), 5 figures.
Accepted to MNRA
Precise LIGO Lensing Rate Predictions for Binary Black Holes
We show how LIGO is expected to detect coalescing binary black holes at
, that are lensed by the intervening galaxy population. Gravitational
magnification, , strengthens gravitational wave signals by ,
without altering their frequencies, which if unrecognised leads to an
underestimate of the event redshift and hence an overestimate of the binary
mass. High magnifications can be reached for coalescing binaries because the
region of intense gravitational wave emission during coalescence is so small
(100km), permitting very close projections between lensing caustics and
gravitational-wave events. Our simulations incorporate accurate waveforms
convolved with the LIGO power spectral density. Importantly, we include the
detection dependence on sky position and orbital orientation, which for the
LIGO configuration translates into a wide spread in observed redshifts and
chirp masses. Currently we estimate a detectable rate of lensed events
\rateEarly{}, that rises to \rateDesign{}, at LIGO's design sensitivity limit,
depending on the high redshift rate of black hole coalescence.Comment: 5 pages, 4 figure
Improving Detection of Gravitational wave Microlensing Using Repeated Signals Induced by Strong Lensing
Microlensing imprints by typical stellar mass lenses on gravitational waves
are challenging to identify in the LIGO and Virgo frequency band because such
effects are weak. However, stellar mass lenses are generally embedded in lens
galaxies such that strong lensing accompanies microlensing. Therefore, events
that are strongly lensed in addition to being microlensed may significantly
improve the inference of the latter. We present a proof of principle
demonstration of how one can use parameter estimation results from one strongly
lensed signal to enhance the inference of the microlensing effects of the other
signal with the Bayesian inference method currently used in gravitational wave
astronomy. We expect this to significantly enhance our future ability to detect
the weak imprints from stellar mass objects on gravitational-wave signals from
colliding compact objects.Comment: 8 pages, 5 figures, presented at TAUP 202
lensingGW: a Python package for lensing of gravitational waves
Advanced LIGO and Advanced Virgo could observe the first lensed gravitational
waves in the coming years, while the future Einstein Telescope could observe
hundreds of lensed events. Ground-based gravitational-wave detectors can
resolve arrival time differences of the order of the inverse of the observed
frequencies. As LIGO/Virgo frequency band spans from a few to a few , the typical time resolution of current interferometers is of the
order of milliseconds. When microlenses are embedded in galaxies or galaxy
clusters, lensing can become more prominent and result in observable time
delays at LIGO/Virgo frequencies. Therefore, gravitational waves could offer an
exciting alternative probe of microlensing. However, currently, only a few
lensing configurations have been worked out in the context of
gravitational-wave lensing. In this paper, we present lensingGW, a Python
package designed to handle both strong and microlensing of compact binaries and
the related gravitational-wave signals. This synergy paves the way for
systematic parameter space investigations and the detection of arbitrary lens
configurations and compact sources. We demonstrate the working mechanism of
lensingGW and its use to study microlenses embedded in galaxies.Comment: 11 pages, 10 figure
Cosmological inference using only gravitational wave observations of binary neutron stars
Gravitational waves emitted during the coalescence of binary neutron star systems are self-calibrating signals. As such, they can provide a direct measurement of the luminosity distance to a source without the need for a cross-calibrated cosmic distance-scale ladder. In general, however, the corresponding redshift measurement needs to be obtained via electromagnetic observations since it is totally degenerate with the total mass of the system. Nevertheless, Fisher matrix studies have shown that, if information about the equation of state of the neutron stars is available, it is possible to extract redshift information from the gravitational wave signal alone. Therefore, measuring the cosmological parameters in pure gravitational-wave fashion is possible. Furthermore, the huge number of sources potentially observable by the Einstein Telescope has led to speculations that the gravitational wave measurement is potentially competitive with traditional methods. The Einstein Telescope is a conceptual study for a third generation gravitational wave detector which is designed to yield 10^3–10^7 detections of binary neutron star systems per year. This study presents the first Bayesian investigation of the accuracy with which the cosmological parameters can be measured using information coming only from the gravitational wave observations of binary neutron star systems by the Einstein Telescope. We find, by direct simulation of 10^3 detections of binary neutron stars, that, within our simplifying assumptions, H_0, Ω_m, Ω_Λ, w_0 and w_1 can be measured at the 95% level with an accuracy of ∼8% , 65%, 39%, 80% and 90%, respectively. We also find, by extrapolation, that a measurement accuracy comparable with current measurements by Planck is possible if the number of gravitational wave events observed is O(10^(6–7)) . We conclude that, while not competitive with electromagnetic missions in terms of significant digits, gravitational waves alone are capable of providing a complementary determination of the dynamics of the Universe
Cosmological inference using only gravitational wave observations of binary neutron stars
Gravitational waves emitted during the coalescence of binary neutron star systems are self- calibrating signals. As such, they can provide a direct measurement of the luminosity distance to a source without the need for a cross-calibrated cosmic distance-scale ladder. In general, how- ever, the corresponding redshift measurement needs to be obtained via electromagnetic observations since it is totally degenerate with the total mass of the system. Nevertheless, Fisher matrix studies have shown that, if information about the equation of state of the neutron stars is available, it is possible to extract redshift information from the gravitational wave signal alone. Therefore, measuring the cosmological parameters in pure gravitational-wave fashion is possible. Furthermore, the huge number of sources potentially observable by the Einstein Telescope has led to speculations that the gravitational wave measurement is potentially competitive with traditional methods. The Einstein Telescope is a conceptual study for a third generation gravitational wave detector which is designed to yield 103 − 107 detections of binary neutron star systems per year. This study presents the first Bayesian investigation of the accuracy with which the cosmological parameters can be measured using information coming only from the gravitational wave observations of binary neutron star systems by Einstein Telescope. We find, by direct simulation of 103 detections of binary neutron stars, that, within our simplifying assumptions, H0, Ωm, ΩΛ, w0 and w1 can be measured at the 95% level with an accuracy of ∼ 8%,65%,39%,80% and 90%, respectively. We also find, by extrapolation, that a measurement accuracy comparable with current measurements by Planck is possible if the number of gravitational wave events observed is O(10^{6−7}).We conclude that, while not competitive with electro-magnetic missions in terms of significant digits, gravitational wave alone are capable of providing a complementary determination of the dynamics of the Universe
Extreme Dark Matter Tests with Extreme Mass Ratio Inspirals
Future space-based laser interferometry experiments such as LISA are expected
to detect (100--1000) stellar-mass compact objects (e.g., black holes,
neutron stars) falling into massive black holes in the centers of galaxies, the
so-called extreme-mass-ratio inspirals (EMRIs). If dark matter forms a "spike"
due to the growth of the massive black hole, it will induce a gravitational
drag on the inspiraling object, changing its orbit and gravitational-wave
signal. We show that detection of even a single dark matter spike from the
EMRIs will severely constrain several popular dark matter candidates, such as
ultralight bosons, keV fermions, MeV--TeV self-annihilating dark matter, and
sub-solar mass primordial black holes, as these candidates would flatten the
spikes through various mechanisms. Future space gravitational wave experiments
could thus have a significant impact on the particle identification of dark
matter.Comment: 10 pages (main body: 5 pages), 2 figure
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