ORCID Profile
0000-0002-4418-3895
Current Organisation
Monash University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Astronomical and Space Sciences | General Relativity and Gravitational Waves | Astronomical sciences | Cosmology and extragalactic astronomy | General relativity and gravitational waves | Astronomical and Space Instrumentation | Applied Statistics | Space instrumentation | Astronomical and Space Sciences not elsewhere classified | Lasers and Quantum Electronics | Classical and Physical Optics | Lasers and quantum electronics | Cosmology and Extragalactic Astronomy |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Physical Sciences | Expanding Knowledge in the Information and Computing Sciences | Scientific Instruments | Expanding Knowledge in Engineering | Expanding Knowledge in Technology
Related Links
Publications
Standard-siren Cosmology Using Gravitational Waves from Binary Black Holes
Publisher: American Astronomical Society
Date: 02-2021
Abstract: Gravitational-wave astronomy provides a unique new way to study the expansion history of the universe. In this work, we investigate the impact future gravitational-wave observatories will have on cosmology. Third-generation observatories like the Einstein Telescope and Cosmic Explorer will be sensitive to essentially all of the binary black hole coalescence events in the universe. Recent work by Farr et al. points out that features in the stellar-mass black hole population break the mass–redshift degeneracy, facilitating precise determination of the Hubble parameter without electromagnetic counterparts or host galaxy catalogs. Using a hierarchical Bayesian inference model, we show that with one year of observations by the Einstein Telescope, the Hubble constant will be measured to ≲1%. We also show that this method can be used to perform Bayesian model selection between cosmological models. As an illustrative ex le, we find that a decisive statement can be made comparing the ΛCDM and RHCT cosmological models using two weeks of data from the Einstein Telescope.
Black-hole spectroscopy, the no-hair theorem, and GW150914: Kerr versus Occam
Publisher: American Physical Society (APS)
Date: 21-01-2021
Toward Robust Detections of Nanohertz Gravitational Waves
Publisher: American Astronomical Society
Date: 10-2023
Detectability of Gravitational Waves from High-Redshift Binaries
Publisher: American Physical Society (APS)
Date: 10-03-2016
Inference with finite time series: Observing the gravitational Universe through windows
Publisher: American Physical Society (APS)
Date: 18-10-2021
Colloquium: Multimessenger astronomy with gravitational waves and high-energy neutrinos
Publisher: American Physical Society (APS)
Date: 02-10-2013
Deep Follow-up for Gravitational-wave Inference: A Case Study with GW151226
Publisher: American Astronomical Society
Date: 04-2023
Abstract: New analyses of gravitational-wave events raise questions about the nature of some events. For ex le, LIGO–Virgo–KAGRA initially determined GW151226 to be a merger with a mass ratio q ≈ 0.5 and effective inspiral spin χ eff ≈ 0.2. However, recent works offer an alternative picture: GW151226 is a lower mass ratio event q ≈ 0.3 with slightly higher spin χ eff ≈ 0.3. This discrepancy has been challenging to resolve, as a wide range of differences are employed for each analysis. This work introduces a “deep follow-up” framework to efficiently compute the posterior odds between two different peaks in parameter space. In doing so, we aim to help resolve disputes about the true nature of gravitational-wave events associated with conflicting astrophysical interpretations. Our proposal is not a replacement for standard inference techniques instead, our method provides a diagnostic tool to understand discrepancies between conflicting results. We demonstrate this method by studying three q–χ eff peaks proposed for GW151226. We find that the ( q ∼ 0.5, χ eff ∼ 0.2) interpretation is only slightly preferred over the ( q ∼ 0.3, χ eff ∼ 0.3) hypothesis with posterior odds of ∼1.7 ± 0.4, suggesting that neither of the two peaks can be ruled out. We discuss strategies to produce more reliable parameter estimation studies in gravitational-wave astronomy.
Evidence for Hierarchical Black Hole Mergers in the Second LIGO–Virgo Gravitational Wave Catalog
Publisher: American Astronomical Society
Date: 07-2021
Suspending test masses in terrestrial millihertz gravitational-wave detectors: A case study with a magnetic assisted torsion pendulum
Publisher: IOP Publishing
Date: 12-04-2017
Search for an Isotropic Gravitational-wave Background with the Parkes Pulsar Timing Array
Publisher: American Astronomical Society
Date: 29-06-2023
Abstract: Pulsar timing arrays aim to detect nanohertz-frequency gravitational waves (GWs). A background of GWs modulates pulsar arrival times and manifests as a stochastic process, common to all pulsars, with a signature spatial correlation. Here we describe a search for an isotropic stochastic gravitational-wave background (GWB) using observations of 30 millisecond pulsars from the third data release of the Parkes Pulsar Timing Array (PPTA), which spans 18 yr. Using current Bayesian inference techniques we recover and characterize a common-spectrum noise process. Represented as a strain spectrum h c = A ( f / 1 yr − 1 ) α , we measure A = 3.1 − 0.9 + 1.3 × 10 − 15 and α = −0.45 ± 0.20, respectively (median and 68% credible interval). For a spectral index of α = −2/3, corresponding to an isotropic background of GWs radiated by inspiraling supermassive black hole binaries, we recover an litude of A = 2.04 − 0.22 + 0.25 × 10 − 15 . However, we demonstrate that the apparent signal strength is time-dependent, as the first half of our data set can be used to place an upper limit on A that is in tension with the inferred common-spectrum litude using the complete data set. We search for spatial correlations in the observations by hierarchically analyzing in idual pulsar pairs, which also allows for significance validation through randomizing pulsar positions on the sky. For a process with α = −2/3, we measure spatial correlations consistent with a GWB, with an estimated false-alarm probability of p ≲ 0.02 (approx. 2 σ ). The long timing baselines of the PPTA and the access to southern pulsars will continue to play an important role in the International Pulsar Timing Array.
Challenges for testing the no-hair theorem with current and planned gravitational-wave detectors
Publisher: American Physical Society (APS)
Date: 14-11-2017
Detecting Gravitational-Wave Memory with LIGO: Implications of GW150914
Publisher: American Physical Society (APS)
Date: 05-08-2016
Constraints on Weak Supernova Kicks from Observed Pulsar Velocities
Publisher: American Astronomical Society
Date: 10-2021
The Imprint of Superradiance on Hierarchical Black Hole Mergers
Publisher: American Astronomical Society
Date: 26-05-2022
Abstract: Ultralight bosons are a proposed solution to outstanding problems in cosmology and particle physics: they provide a dark-matter candidate while potentially explaining the strong charge-parity problem. If they exist, ultralight bosons can interact with black holes through the superradiant instability. In this work we explore the consequences of this instability on the evolution of hierarchical black holes within dense stellar clusters. By reducing the spin of in idual black holes, superradiance reduces the recoil velocity of merging binary black holes, which, in turn, increases the retention fraction of hierarchical merger remnants. We show that the existence of ultralight bosons with mass 2 × 10 −14 ≲ μ /eV ≲ 2 × 10 −13 would lead to an increased rate of hierarchical black hole mergers in nuclear star clusters. An ultralight boson in this energy range would result in up to ≈60% more present-day nuclear star clusters supporting hierarchical growth. The presence of an ultralight boson can also double the rate of intermediate-mass black hole mergers to ≈0.08 Gpc −3 yr −1 in the local universe. These results imply that a select range of ultralight boson masses can have far-reaching consequences for the population of black holes in dense stellar environments. Future studies into black hole cluster populations and the spin distribution of hierarchically formed black holes will test this scenario.
The basic physics of the binary black hole merger GW150914
Publisher: Wiley
Date: 04-10-2016
Orbital Dynamics and Extreme Scattering Event Properties from Long-term Scintillation Observations of PSR J1603−7202
Publisher: American Astronomical Society
Date: 28-06-2022
Abstract: We model long-term variations in the scintillation of binary pulsar PSR J1603−7202, observed by the 64 m Parkes radio telescope (Murriyang) between 2004 and 2016. We find that the time variation in the scintillation arc curvature is well-modeled by scattering from an anisotropic thin screen of plasma between the Earth and the pulsar. Using our scintillation model, we measure the inclination angle and longitude of ascending node of the orbit, yielding a significant improvement over the constraints from pulsar timing. From our measurement of the inclination angle, we place a lower bound on the mass of J1603−7202's companion of ≳0.5 M ⊙ assuming a pulsar mass of ≳1.2 M ⊙ . We find that the scintillation arcs are most pronounced when the electron column density along the line of sight is increased, and that arcs are present during a known extreme scattering event. We measure the distance to the interstellar plasma and its velocity, and we discuss some structures seen in in idual scintillation arcs within the context of our model.
Flexible and Accurate Evaluation of Gravitational-wave Malmquist Bias with Machine Learning
Publisher: American Astronomical Society
Date: 03-2022
Abstract: Many astronomical surveys are limited by the brightness of the sources, and gravitational-wave searches are no exception. The detectability of gravitational waves from merging binaries is affected by the mass and spin of the constituent compact objects. To perform unbiased inference on the distribution of compact binaries, it is necessary to account for this selection effect, which is known as Malmquist bias. Since systematic error from selection effects grows with the number of events, it will be increasingly important over the coming years to accurately estimate the observational selection function for gravitational-wave astronomy. We employ density estimation methods to accurately and efficiently compute the compact binary coalescence selection function. We introduce a simple pre-processing method, which significantly reduces the complexity of the required machine-learning models. We demonstrate that our method has smaller statistical errors at comparable computational cost than the method currently most widely used allowing us to probe narrower distributions of spin magnitudes. The currently used method leaves 10%–50% of the interesting black hole spin models inaccessible our new method can probe % of the models and has a lower uncertainty for % of the models.
First Search for Gravitational Waves from Known Pulsars with Advanced LIGO
Publisher: American Astronomical Society
Date: 07-04-2017
A follow-up on intermediate-mass black hole candidates in the second LIGO–Virgo observing run with the Bayes Coherence Ratio
Publisher: Oxford University Press (OUP)
Date: 29-08-2022
Abstract: The detection of an intermediate-mass black hole population (102–106 M⊙) will provide clues to their formation environments (e.g. discs of active galactic nuclei, globular clusters) and illuminate a potential pathway to produce supermassive black holes. Ground-based gravitational-wave detectors are sensitive to mergers that can form intermediate-mass black holes weighing up to ∼450 M⊙. However, ground-based detector data contain numerous incoherent short duration noise transients that can mimic the gravitational-wave signals from merging intermediate-mass black holes, limiting the sensitivity of searches. Here, we follow-up on binary black hole merger candidates using a ranking statistic that measures the coherence or incoherence of triggers in multiple-detector data. We use this statistic to rank candidate events, initially identified by all-sky search pipelines, with lab-frame total masses ≳ 55 M⊙ using data from LIGO’s second observing run. Our analysis does not yield evidence for new intermediate-mass black holes. However, we find support for eight stellar-mass binary black holes not reported in the first LIGO–Virgo gravitational wave transient catalogue GWTC-1, seven of which have been previously reported by other catalogues.
GW190521: Orbital Eccentricity and Signatures of Dynamical Formation in a Binary Black Hole Merger Signal
Publisher: American Astronomical Society
Date: 23-10-2020
Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA
Publisher: Springer Science and Business Media LLC
Date: 26-04-2018
DOI: 10.1007/S41114-018-0012-9
Abstract: We present possible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron star systems, which are the most promising targets for multi-messenger astronomy. The ability to localize the sources of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and $$90\\%$$ 90 % credible regions can be as large as thousands of square degrees when only two sensitive detectors are operational. Determining the sky position of a significant fraction of detected signals to areas of 5– $$20~\\mathrm {deg}^2$$ 20 deg 2 requires at least three detectors of sensitivity within a factor of $$\\sim 2$$ ∼ 2 of each other and with a broad frequency bandwidth. When all detectors, including KAGRA and the third LIGO detector in India, reach design sensitivity, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.
On the Evidence for a Common-spectrum Process in the Search for the Nanohertz Gravitational-wave Background with the Parkes Pulsar Timing Array
Publisher: American Astronomical Society
Date: 08-2021
Detectability of eccentric compact binary coalescences with advanced gravitational-wave detectors
Publisher: American Physical Society (APS)
Date: 12-03-2015
Effects of waveform model systematics on the interpretation of GW150914
Publisher: IOP Publishing
Date: 12-04-2017
Measuring the Binary Black Hole Mass Spectrum with an Astrophysically Motivated Parameterization
Publisher: American Astronomical Society
Date: 05-04-2018
Inferring the population properties of binary neutron stars with gravitational-wave measurements of spin
Publisher: American Physical Society (APS)
Date: 08-2018
Consistency of the Parkes Pulsar Timing Array Signal with a Nanohertz Gravitational-wave Background
Publisher: American Astronomical Society
Date: 06-2022
Abstract: Pulsar timing array experiments have recently reported strong evidence for a common-spectrum stochastic process with a strain spectral index consistent with that expected of a nanohertz-frequency gravitational-wave background, but with negligible yet non-zero evidence for spatial correlations required for a definitive detection. However, it was pointed out by the Parkes Pulsar Timing Array (PPTA) collaboration that the same models used in recent analyses resulted in strong evidence for a common-spectrum process in simulations where none is present. In this work, we introduce a methodology to distinguish pulsar power spectra with the same litude from noise power spectra of similar but distinct litudes. The former is the signature of a spatially uncorrelated pulsar term of a nanohertz gravitational-wave background, whereas the latter could represent ensemble pulsar noise properties. We test the methodology on simulated data sets. We find that the reported common process in PPTA pulsars is indeed consistent with the spectral feature of a pulsar term. We recommend this methodology as one of the validity tests that the real astrophysical and cosmological backgrounds should pass, as well as for inferences about the spatially uncorrelated component of the background.
Black Hole Genealogy: Identifying Hierarchical Mergers with Gravitational Waves
Publisher: American Astronomical Society
Date: 14-09-2020
Detecting Gravitational Wave Memory without Parent Signals
Publisher: American Physical Society (APS)
Date: 04-05-2017
Identification of noise artifacts in searches for long-duration gravitational-wave transients
Publisher: IOP Publishing
Date: 18-04-2012
Meet the Parents: The Progenitor Binary for the Supermassive Black Hole Candidate in E1821+643
Publisher: American Astronomical Society
Date: 03-2023
Abstract: The remnants of binary black hole mergers can be given recoil kick velocities up to 5000 km s −1 due to anisotropic emission of gravitational waves. E1821+643 is a recoiling supermassive black hole candidate with spectroscopically offset, broad emission lines, consistent with motion of the black hole at ∼2100 km s −1 along the line of sight relative to its host galaxy. This suggests a recoil kick of ∼2200 km s −1 . Such a kick is powerful enough to eject E1821+643 from its M gal ∼ 2 × 10 12 M ⊙ host galaxy. In this work, we address the question: assuming that E1821+643 is a recoiling black hole, what are the likely properties of the progenitor binary that formed E1821+643? Using astrophysically motivated priors, we infer that E1821+643 was likely formed from a binary black hole system with masses of m 1 ∼ 1.9 − 0.4 + 0.5 × 10 9 M ⊙ , m 2 ∼ 8.1 − 3.2 + 3.9 × 10 8 M ⊙ (90% credible intervals). Given our model, the black holes in this binary were likely to be spinning rapidly with dimensionless spin magnitudes of χ 1 = 0.87 − 0.26 + 0.11 , χ 2 = 0.77 − 0.37 + 0.19 . Such a high recoil velocity is impossible for spins aligned to the orbital angular momentum axis. This suggests that the progenitor for E1821+643 merged in hot gas, which is thought to provide an environment where spin alignment from accretion proceeds slowly relative to the merger timescale. We infer that E1821+643, if it is a recoiling black hole, is likely to be a rapidly rotating black hole with a dimensionless spin of χ = 0.92 ± 0.04. A 2.6 × 10 9 M ⊙ black hole, recoiling from a gas-rich environment at v ∼ 2200 km s −1 , is likely to persist as an active galactic nucleus for ∼10 7 yr, in which time it traverses ∼25 kpc.
Gravitational-wave inference for eccentric binaries: the argument of periapsis
Publisher: Oxford University Press (OUP)
Date: 19-10-2022
Abstract: Gravitational waves from binary black hole mergers have allowed us to directly observe stellar-mass black hole binaries for the first time and therefore explore their formation channels. One of the ways to infer how a binary system is assembled is by measuring the system’s orbital eccentricity. Current methods of parameter estimation do not include all physical effects of eccentric systems, such as spin-induced precession, higher order modes, and the initial argument of periapsis: an angle describing the orientation of the orbital ellipse. We explore how varying the argument of periapsis changes gravitational waveforms and study its effect on the inference of astrophysical parameters. We use the eccentric spin-aligned waveforms TEOBResumS and SEOBNRE to measure the change in the waveforms as the argument of periapsis is changed. We find that the argument of periapsis could already be impacting analyses performed with TEOBResumS. However, it is likely to be well resolvable in the foreseeable future only for the loudest events observed by LIGO–Virgo–KAGRA. The systematic error in previous, low-eccentricity analyses that have not considered the argument of periapsis is likely to be small.
Do unequal-mass binary black hole systems have larger χeff? Probing correlations with copulas in gravitational-wave astronomy
Publisher: Oxford University Press (OUP)
Date: 18-10-2022
Abstract: The formation history of binary black hole systems is imprinted on the distribution of their masses, spins, and eccentricity. While much has been learned studying these parameters in turn, recent studies have explored the joint distribution of binary black hole parameters in two or more dimensions. Most notably, it has recently been argued that binary black hole mass ratio and effective inspiral spin χeff are anticorrelated. We point out a previously overlooked subtlety in such 2D population studies: in order to conduct a controlled test for correlation, one ought to fix the two marginal distributions – lest the purported correlation be driven by improved fit in just one dimension. We address this subtlety using a tool from applied statistics: the copula density function. We use the previous work correlating mass ratio and χeff as a case study to demonstrate the power of copulas in gravitational-wave astronomy while scrutinizing their astrophysical inferences. Our findings, however, affirm their conclusions that binary black holes with unequal component masses exhibit larger χeff (98.7 per cent credibility). We conclude by discussing potential astrophysical implications of these findings as well as prospects for future studies using copulas.
Bayesian inference for compact binary coalescences with bilby : validation and application to the first LIGO–Virgo gravitational-wave transient catalogue
Publisher: Oxford University Press (OUP)
Date: 21-09-2020
Abstract: Gravitational waves provide a unique tool for observational astronomy. While the first LIGO–Virgo catalogue of gravitational-wave transients (GWTC-1) contains 11 signals from black hole and neutron star binaries, the number of observations is increasing rapidly as detector sensitivity improves. To extract information from the observed signals, it is imperative to have fast, flexible, and scalable inference techniques. In a previous paper, we introduced bilby: a modular and user-friendly Bayesian inference library adapted to address the needs of gravitational-wave inference. In this work, we demonstrate that bilby produces reliable results for simulated gravitational-wave signals from compact binary mergers, and verify that it accurately reproduces results reported for the 11 GWTC-1 signals. Additionally, we provide configuration and output files for all analyses to allow for easy reproduction, modification, and future use. This work establishes that bilby is primed and ready to analyse the rapidly growing population of compact binary coalescence gravitational-wave signals.
Signs of Eccentricity in Two Gravitational-wave Signals May Indicate a Subpopulation of Dynamically Assembled Binary Black Holes
Publisher: American Astronomical Society
Date: 11-2021
Gravitational-wave memory: Waveforms and phenomenology
Publisher: American Physical Society (APS)
Date: 17-09-2018
Erratum: “Building Better Spin Models for Merging Binary Black Holes: Evidence for Nonspinning and Rapidly Spinning Nearly Aligned Subpopulations” (2021, ApJL, 921, L15)
Publisher: American Astronomical Society
Date: 09-2022
Improving pulsar-timing solutions through dynamic pulse fitting
Publisher: Oxford University Press (OUP)
Date: 06-06-2023
Abstract: Precision pulsar timing is integral to the detection of the nanohertz stochastic gravitational-wave background as well as understanding the physics of neutron stars. Conventional pulsar timing often uses fixed time and frequency-averaged templates to determine the pulse times of arrival, which can lead to reduced accuracy when the pulse profile evolves over time. We illustrate a dynamic timing method that fits each observing epoch using basis functions. By fitting each epoch separately, we allow for the evolution of the pulse shape epoch to epoch. We apply our method to PSR J1103−5403 and find evidence that it undergoes mode changing, making it the fourth millisecond pulsar to exhibit such behaviour. Our method, which is able to identify and time a single mode, yields a timing solution with a root-mean-square error of $1.343$ µs, a factor of 1.78 improvement over template fitting on both modes. In addition, the white-noise litude is reduced 4.3 times, suggesting that fitting the full data set causes the mode changing to be incorrectly classified as white noise. This reduction in white noise boosts the signal-to-noise ratio of a gravitational-wave background signal for this particular pulsar by 32 per cent. We discuss the possible applications for this method of timing to study pulsar magnetospheres and further improve the sensitivity of searches for nanohertz gravitational waves.
Heavy Double Neutron Stars: Birth, Midlife, and Death
Publisher: American Astronomical Society
Date: 03-2021
Abstract: Radio pulsar observations probe the lives of Galactic double neutron star (DNS) systems while gravitational waves enable us to study extragalactic DNS in their final moments. By combining measurements from radio and gravitational-wave astronomy, we seek to gain a more complete understanding of DNS from formation to merger. We analyze the recent gravitational-wave binary neutron star mergers GW170817 and GW190425 in the context of other DNS known from radio astronomy. By employing a model for the birth and evolution of DNS, we measure the mass distribution of DNS at birth, at midlife (in the radio), and at death (in gravitational waves). We consider the hypothesis that the high-mass gravitational-wave event GW190425 is part of a subpopulation formed through unstable case BB mass transfer, which quickly merge in ∼10–100 Myr. We find only mild evidence to support this hypothesis and that GW190425 is not a clear outlier from the radio population as previously claimed. If there are fast-merging binaries, we estimate that they constitute 8%–79% of DNS at birth (90% credibility). We estimate the typical delay time between the birth and death of fast-merging binaries to be ≈5–401 Myr (90% credibility). We discuss the implications for radio and gravitational-wave astronomy.
A Rosetta Stone for Eccentric Gravitational Waveform Models
Publisher: American Astronomical Society
Date: 09-2022
Abstract: Orbital eccentricity is a key signature of dynamical binary black hole formation. The gravitational waves from a coalescing binary contain information about its orbital eccentricity, which may be measured if the binary retains sufficient eccentricity near merger. Dedicated waveforms are required to measure eccentricity. Several models have been put forward, and show good agreement with numerical relativity at the level of a few percent or better. However, there are multiple ways to define eccentricity for inspiralling systems, and different models internally use different definitions of eccentricity, making it difficult to compare eccentricity measurements directly. In this work, we systematically compare two eccentric waveform models, SEOBNRE and TEOBResumS , by developing a framework to translate between different definitions of eccentricity. This mapping is constructed by minimizing the relative mismatch between the two models over eccentricity and reference frequency, before evolving the eccentricity of one model to the same reference frequency as the other model. We show that for a given value of eccentricity passed to SEOBNRE , one must input a 20%–50% smaller value of eccentricity to TEOBResumS in order to obtain a waveform with the same empirical eccentricity. We verify this mapping by repeating our analysis for eccentric numerical relativity simulations, demonstrating that TEOBResumS reports a correspondingly smaller value of eccentricity than SEOBNRE .
Measuring the Primordial Gravitational-Wave Background in the Presence of Astrophysical Foregrounds
Publisher: American Physical Society (APS)
Date: 09-12-2020
GW170608: Observation of a 19 Solar-mass Binary Black Hole Coalescence
Publisher: American Astronomical Society
Date: 18-12-2017
A gravitational wave observatory operating beyond the quantum shot-noise limit
Publisher: Springer Science and Business Media LLC
Date: 11-09-2011
DOI: 10.1038/NPHYS2083
Statistical properties of astrophysical gravitational-wave backgrounds
Publisher: American Physical Society (APS)
Date: 17-04-2014
A gravitational-wave standard siren measurement of the Hubble constant
Publisher: Springer Science and Business Media LLC
Date: 16-10-2017
DOI: 10.1038/NATURE24471
Abstract: On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817-a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO-Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identification of an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first 'multi-messenger' astronomical observation. Such observations enable GW170817 to be used as a 'standard siren' (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic 'distance ladder': the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. This value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.
Signatures of Mass Ratio Reversal in Gravitational Waves from Merging Binary Black Holes
Publisher: American Astronomical Society
Date: 10-2022
Abstract: The spins of merging binary black holes offer insights into their formation history. Recently it has been argued that in the isolated binary evolution of two massive stars the firstborn black hole is slowly rotating, while the progenitor of the second-born black hole can be tidally spun up if the binary is tight enough. Naively, one might therefore expect that only the less massive black hole in merging binaries exhibits nonnegligible spin. However, if the mass ratio of the binary is “reversed” (typically during the first mass transfer episode), it is possible for the tidally spun up second-born to become the more massive black hole. We study the properties of such mass ratio reversed binary black hole mergers using a large set of 560 population synthesis models. We find that the more massive black hole is formed second in ≳70% of binary black holes observable by LIGO, Virgo, and KAGRA for most model variations we consider, with typical total masses ≳20 M ⊙ and mass ratios q = m 2 / m 1 ∼ 0.7 (where m 1 m 2 ). The formation history of these systems typically involves only stable mass transfer episodes. The second-born black hole has nonnegligible spin ( χ 0.05) in up to 25% of binary black holes, with among those the more (less) massive black hole is spinning in 0%–80% (20%–100%) of the cases, varying greatly in our models. We discuss our models in the context of several observed gravitational-wave events and the observed mass ratio—effective spin correlation.
Searching for gravitational-wave transients with a qualitative signal model: Seedless clustering strategies
Publisher: American Physical Society (APS)
Date: 22-10-2013
Nuclear Physics with Gravitational Waves from Neutron Stars Disrupted by Black Holes
Publisher: American Astronomical Society
Date: 05-2023
Abstract: Gravitational waves from neutron star–black hole (NSBH) mergers that undergo tidal disruption provide a potential avenue to study the equation of state of neutron stars and hence the behavior of matter at its most extreme densities. We present a phenomenological model for the gravitational-wave signature of tidal disruption, which allows us to measure the disruption time. We carry out a study with mock data, assuming an optimistically nearby NSBH event with parameters tuned for measuring the tidal disruption. We show that a two-detector network of 40 km Cosmic Explorer instruments can measure the time of disruption with a precision of ≈0.5 ms, which corresponds to a constraint on the neutron star radius of ≈0.7 km (90% credibility). This radius constraint is wider than the constraint obtained by measuring the tidal deformability of the neutron star of the same system during the inspiral. Moreover, the neutron star radius is likely to be more tightly constrained using binary neutron star mergers. While NSBH mergers are important for the information they provide about stellar and binary astrophysics, they are unlikely to provide insights into nuclear physics beyond what we will already know from binary neutron star mergers.
Gravitational waves from fallback accretion onto neutron stars
Publisher: American Astronomical Society
Date: 21-11-2012
Determining the population properties of spinning black holes
Publisher: American Physical Society (APS)
Date: 26-07-2017
Implications of Eccentric Observations on Binary Black Hole Formation Channels
Publisher: American Astronomical Society
Date: 11-2021
Abstract: Orbital eccentricity is one of the most robust discriminators for distinguishing between dynamical and isolated formation scenarios of binary black hole mergers using gravitational-wave observatories such as LIGO and Virgo. Using state-of-the-art cluster models, we show how selection effects impact the detectable distribution of eccentric mergers from clusters. We show that the observation (or lack thereof) of eccentric binary black hole mergers can significantly constrain the fraction of detectable systems that originate from dynamical environments, such as dense star clusters. After roughly 150 observations, observing no eccentric binary signals would indicate that clusters cannot make up the majority of the merging binary black hole population in the local universe (95% credibility). However, if dense star clusters dominate the rate of eccentric mergers and a single system is confirmed to be measurably eccentric in the first and second gravitational-wave transient catalogs, clusters must account for at least 14% of detectable binary black hole mergers. The constraints on the fraction of detectable systems from dense star clusters become significantly tighter as the number of eccentric observations grows and will be constrained to within 0.5 dex once 10 eccentric binary black holes are observed.
Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
Publisher: American Astronomical Society
Date: 16-10-2017
Correlated noise in networks of gravitational-wave detectors: Subtraction and mitigation
Publisher: American Physical Society (APS)
Date: 11-07-2014
Measuring the non-Gaussian stochastic gravitational-wave background: A method for realistic interferometer data
Publisher: American Physical Society (APS)
Date: 26-02-2013
Measuring the Properties of Active Galactic Nuclei Disks with Gravitational Waves
Publisher: American Astronomical Society
Date: 26-05-2022
Abstract: Active galactic nuclei (AGNs) are promising environments for the assembly of merging binary black hole (BBH) systems. Interest in AGNs as nurseries for merging BBHs is rising, following the detection of gravitational waves from a BBH system from the purported pair-instability mass gap, most notably GW190521. AGNs have also been invoked to explain the formation of the high-mass-ratio system GW190814. We draw on simulations of BBH systems in AGNs to propose a phenomenological model for the distribution of black hole spins of merging binaries in AGN disks. The model incorporates distinct features that make the AGN channel potentially distinguishable from other channels, such as assembly in the field and in globular clusters. The model parameters can be mapped heuristically to the age and density of the AGN disks. We estimate the extent to which different populations of mergers in AGNs can be distinguished. If the majority of merging black holes are assembled in AGNs, future gravitational-wave observations may provide insights into the dynamics of AGN disks.
Correlated magnetic noise in global networks of gravitational-wave detectors: Observations and implications
Publisher: American Physical Society (APS)
Date: 26-06-2013
Method for estimation of gravitational-wave transient model parameters in frequency-time maps
Publisher: IOP Publishing
Date: 05-08-2014
Polarization-Based Tests of Gravity with the Stochastic Gravitational-Wave Background
Publisher: American Physical Society (APS)
Date: 07-12-2017
On the origin of GW190425
Publisher: Oxford University Press (OUP)
Date: 11-05-2020
Abstract: The LIGO/Virgo collaborations recently announced the detection of a binary neutron star merger, GW190425. The mass of GW190425 is significantly larger than the masses of Galactic double neutron stars known through radio astronomy. We hypothesize that GW190425 formed differently from Galactic double neutron stars, via unstable ‘case BB’ mass transfer. According to this hypothesis, the progenitor of GW190425 was a binary consisting of a neutron star and a ∼4–$5\\, {\\mathrm{ M}_\\odot }$ helium star, which underwent common-envelope evolution. Following the supernova of the helium star, an eccentric double neutron star was formed, which merged in ${\\lesssim }10\\, {\\rm Myr}$. The helium star progenitor may explain the unusually large mass of GW190425, while the short time to merger may explain why similar systems are not observed in radio. To test this hypothesis, we measure the eccentricity of GW190425 using publicly available LIGO/Virgo data. We constrain the eccentricity at $10\\, {\\rm Hz}$ to be e ≤ 0.007 with $90{{\\ \\rm per\\ cent}}$ confidence. This provides no evidence for or against the unstable mass transfer scenario, because the binary is likely to have circularized to e ≲ 10−4 by the time it was detected. Future detectors will help to reveal the formation channel of mergers similar to GW190425 using eccentricity measurements.
Probing Extremal Gravitational-wave Events with Coarse-grained Likelihoods
Publisher: American Astronomical Society
Date: 02-2022
Abstract: As catalogs of gravitational-wave transients grow, new records are set for the most extreme systems observed to date. The most massive observed black holes probe the physics of pair-instability supernovae while providing clues about the environments in which binary black hole systems are assembled. The least massive black holes, meanwhile, allow us to investigate the purported neutron star–black hole mass gap, and binaries with unusually asymmetric mass ratios or large spins inform our understanding of binary and stellar evolution. Existing outlier tests generally implement leave-one-out analyses, but these do not account for the fact that the event being left out was by definition an extreme member of the population. This results in a bias in the evaluation of outliers. We correct for this bias by introducing a coarse-graining framework to investigate whether these extremal events are true outliers or whether they are consistent with the rest of the observed population. Our method enables us to study extremal events while testing for population model misspecification. We show that this ameliorates biases present in the leave-one-out analyses commonly used within the gravitational-wave community. Applying our method to results from the second LIGO–Virgo transient catalog, we find qualitative agreement with the conclusions of Abbott et al. GW190814 is an outlier because of its small secondary mass. We find that neither GW190412 nor GW190521 is an outlier.
Four Eccentric Mergers Increase the Evidence that LIGO–Virgo–KAGRA’s Binary Black Holes Form Dynamically
Publisher: American Astronomical Society
Date: 12-2022
Abstract: The growing population of compact binary mergers detected with gravitational waves contains multiple events that are challenging to explain through isolated binary evolution. Such events have higher masses than are expected in isolated binaries, component spin tilt angles that are misaligned, and/or nonnegligible orbital eccentricities. We investigate the orbital eccentricities of 62 binary black hole candidates from the third gravitational-wave transient catalog of the LIGO–Virgo–KAGRA Collaboration with an aligned-spin, moderate-eccentricity waveform model. Within this framework, we find that at least four of these events show significant support for eccentricity e 10 ≥ 0.1 at a gravitational-wave frequency of 10 Hz ( % credibility, under a log-uniform eccentricity prior that spans the range 10 −4 e 10 0.2). Two of these events are new additions to the population: GW191109 and GW200208_22. If the four eccentric candidates are truly eccentric, our results suggest that densely populated star clusters may produce 100% of the observed mergers. However, it remains likely that other formation environments with higher yields of eccentric mergers—for ex le, active galactic nuclei—also contribute. We estimate that we will be able to confidently distinguish which formation channel dominates the eccentric merger rate after ≳80 detections of events with e 10 ≥ 0.05 at LIGO–Virgo sensitivity, with only ∼5 detectably eccentric events required to distinguish formation channels with third-generation gravitational-wave detectors.
Long gravitational-wave transients and associated detection strategies for a network of terrestrial interferometers
Publisher: American Physical Society (APS)
Date: 11-04-2011
Seedless clustering in all-sky searches for gravitational-wave transients
Publisher: American Physical Society (APS)
Date: 25-03-2014
Treatment of calibration uncertainty in multi-baseline cross-correlation searches for gravitational waves
Publisher: IOP Publishing
Date: 05-03-2014
Measuring neutron-star ellipticity with measurements of the stochastic gravitational-wave background
Publisher: American Physical Society (APS)
Date: 20-06-2014
Parameter estimation in searches for the stochastic gravitational-wave background
Publisher: American Physical Society (APS)
Date: 24-10-2012
Toward the Unambiguous Identification of Supermassive Binary Black Holes through Bayesian Inference
Publisher: American Astronomical Society
Date: 08-09-2020
Sensitivity curves for searches for gravitational-wave backgrounds
Publisher: American Physical Society (APS)
Date: 12-12-2013
All-sky radiometer for narrowband gravitational waves using folded data
Publisher: American Physical Society (APS)
Date: 12-09-2018
Thin layer coulometric determination of nitrate in fresh waters
Publisher: Elsevier BV
Date: 09-2012
DOI: 10.1016/J.ACA.2012.07.026
Abstract: A nitrate ion-selective electrode (ISE) employing a permeable tubular membrane impregnated with a conventional ISE cocktail has been used successfully in the coulometric analysis of nitrate in fresh waters. The liquid ISE membrane comprising a nitrate ionophore [tridodecylmethylammonium nitrate (TDMAN)], lipophilic electrolyte [tetradodecyl-ammoniumtetrakis(4-chlorophenyl)borate (ETH 500)] and plasticizer [bis(3-ethyl-hexyl)sebacate (DOS)] was supported on a porous polypropylene tube. Coulometric analysis with the tubular membrane ISE showed that nitrate could be detected in the range 10-100 μM with a precision of 2.3% relative standard deviation (RSD), limit of detection of 1.1 μM and relative accuracy of 4.4% compared to a certified reference material (CRM) Lake s le.
Probing the Efficiency of Tidal Synchronization in Outspiralling Double White Dwarf Binaries with LISA
Publisher: American Astronomical Society
Date: 06-2023
Abstract: Compact-object binaries including a white dwarf component are unique among gravitational-wave sources because their evolution is governed not just by general relativity and tides, but also by mass transfer. While the black hole and neutron star binaries observed with ground-based gravitational-wave detectors are driven to inspiral due to the emission of gravitational radiation—manifesting as a “chirp-like” gravitational-wave signal—the astrophysical processes at work in double white dwarf (DWD) systems can cause the inspiral to stall and even reverse into an outspiral. The dynamics of the DWD outspiral thus encode information about tides, which tell us about the behavior of electron-degenerate matter. We carry out a population study to determine the effect of the strength of tides on the distributions of the DWD binary parameters that the Laser Interferometer Space Antenna (LISA) will be able to constrain. We find that the strength of tidal coupling parameterized via the tidal synchronization timescale at the onset of mass transfer affects the distribution of gravitational-wave frequencies and frequency derivatives for detectably mass-transferring DWD systems. Using a hierarchical Bayesian framework informed by binary population synthesis simulations, we demonstrate how this parameter can be inferred using LISA observations. By measuring the population properties of DWDs, LISA will be able to probe the behavior of electron-degenerate matter.
TARGET VOLATILITY STRATEGIES FOR GROUP SELF-ANNUITY PORTFOLIOS
Publisher: Cambridge University Press (CUP)
Date: 11-04-2022
DOI: 10.1017/ASB.2022.7
Abstract: While the current pandemic is causing mortality shocks globally, the management of longevity risk remains a major challenge for both in iduals and institutions. It is high time there be private market solutions designed for efficient longevity risk transfer among various stakeholders such as in iduals, pension funds and annuity providers. From in iduals’ point of view, appealing features of post-retirement solutions include stable and satisfactory benefit levels, flexibility, meeting bequest preferences and low fees. This paper proposes a dynamic target volatility strategy for group self-annuitization (GSA) schemes aimed at enhancing living benefits for pool participants. More specifically, we suggest investing GSA funds in a portfolio consisting of equity and cash, continuously rebalanced to maintain a target volatility level. The performance of a dynamic target volatility strategy is assessed against the static case which does not involve portfolio rebalancing. Benefit profiles are assessed by analysing quantiles and alternative strategies involving varying equity compositions. The case of death benefits is included, and the fund dynamics analysed by assessing resulting investment returns and the mortality credits. Overall, higher living benefit profiles are obtained under a dynamic target volatility strategy. From the analysis performed, a trade-off between the equity proportion and the impact on the lower quantile of the living benefit amount emerges, suggesting an optimal proportion of equity composition.
Memory effect or cosmic string? Classifying gravitational-wave bursts with Bayesian inference
Publisher: American Physical Society (APS)
Date: 07-07-2020
Self-supervised clustering on image-subtracted data with deep-embedded self-organizing map
Publisher: Oxford University Press (OUP)
Date: 02-11-2022
Abstract: Developing an effective automatic classifier to separate genuine sources from artifacts is essential for transient follow-ups in wide-field optical surveys. The identification of transient detections from the subtraction artifacts after the image differencing process is a key step in such classifiers, known as real-bogus classification problem. We apply a self-supervised machine learning model, the deep-embedded self-organizing map (DESOM) to this ‘real-bogus’ classification problem. DESOM combines an autoencoder and a self-organizing map to perform clustering in order to distinguish between real and bogus detections, based on their dimensionality-reduced representations. We use 32 × 32 normalized detection thumbnails as the input of DESOM. We demonstrate different model training approaches, and find that our best DESOM classifier shows a missed detection rate of $6.6{{\\ \\rm per\\,cent}}$ with a false-positive rate of $1.5{{\\ \\rm per\\,cent}}$. DESOM offers a more nuanced way to fine-tune the decision boundary identifying likely real detections when used in combination with other types of classifiers, e.g. built on neural networks or decision trees. We also discuss other potential usages of DESOM and its limitations.
Estimates of maximum energy density of cosmological gravitational-wave backgrounds
Publisher: American Physical Society (APS)
Date: 24-11-2014
Optimal Search for an Astrophysical Gravitational-Wave Background
Publisher: American Physical Society (APS)
Date: 16-04-2018
Exploring a search for long-duration transient gravitational waves associated with magnetar bursts
Publisher: IOP Publishing
Date: 20-07-2017
Effects of transients in LIGO suspensions on searches for gravitational waves
Publisher: AIP Publishing
Date: 12-2017
DOI: 10.1063/1.5000264
Abstract: This paper presents an analysis of the transient behavior of the Advanced LIGO (Laser Interferometer Gravitational-wave Observatory) suspensions used to seismically isolate the optics. We have characterized the transients in the longitudinal motion of the quadruple suspensions during Advanced LIGO’s first observing run. Propagation of transients between stages is consistent with modeled transfer functions, such that transient motion originating at the top of the suspension chain is significantly reduced in litude at the test mass. We find that there are transients seen by the longitudinal motion monitors of quadruple suspensions, but they are not significantly correlated with transient motion above the noise floor in the gravitational wave strain data, and therefore do not present a dominant source of background noise in the searches for transient gravitational wave signals. Using the suspension transfer functions, we compared the transients in a week of gravitational wave strain data with transients from a quadruple suspension. Of the strain transients between 10 and 60 Hz, 84% are loud enough that they would have appeared above the sensor noise in the top stage quadruple suspension monitors if they had originated at that stage at the same frequencies. We find no significant temporal correlation with the suspension transients in that stage, so we can rule out suspension motion originating at the top stage as the cause of those transients. However, only 3.2% of the gravitational wave strain transients are loud enough that they would have been seen by the second stage suspension sensors, and none of them are above the sensor noise levels of the penultimate stage. Therefore, we cannot eliminate the possibility of transient noise in the detectors originating in the intermediate stages of the suspension below the sensing noise.
Mock data and science challenge for detecting an astrophysical stochastic gravitational-wave background with Advanced LIGO and Advanced Virgo
Publisher: American Physical Society (APS)
Date: 02-09-2015
Hunting Gravitational Waves with Multi-Messenger Counterparts: Australia's Role
Publisher: Cambridge University Press (CUP)
Date: 2015
DOI: 10.1017/PASA.2015.49
Abstract: The first observations by a worldwide network of advanced interferometric gravitational wave detectors offer a unique opportunity for the astronomical community. At design sensitivity, these facilities will be able to detect coalescing binary neutron stars to distances approaching 400 Mpc, and neutron star–black hole systems to 1 Gpc. Both of these sources are associated with gamma-ray bursts which are known to emit across the entire electromagnetic spectrum. Gravitational wave detections provide the opportunity for ‘multi-messenger’ observations, combining gravitational wave with electromagnetic, cosmic ray, or neutrino observations. This review provides an overview of how Australian astronomical facilities and collaborations with the gravitational wave community can contribute to this new era of discovery, via contemporaneous follow-up observations from the radio to the optical and high energy. We discuss some of the frontier discoveries that will be made possible when this new window to the Universe is opened.
Constraining Short Gamma-Ray Burst Jet Properties with Gravitational Waves and Gamma-Rays
Publisher: American Astronomical Society
Date: 14-04-2020
Did Goryachev et al. detect megahertz gravitational waves?
Publisher: American Physical Society (APS)
Date: 12-11-2021
Searching for anisotropy in the distribution of binary black hole mergers
Publisher: American Physical Society (APS)
Date: 13-11-2020
Probing the anisotropies of a stochastic gravitational-wave background using a network of ground-based laser interferometers
Publisher: American Physical Society (APS)
Date: 04-12-2009
Detecting compact binary coalescences with seedless clustering
Publisher: American Physical Society (APS)
Date: 14-10-2014
Detecting Gravitational-Wave Transients at 5σ: A Hierarchical Approach
Publisher: American Physical Society (APS)
Date: 27-10-2015
When models fail: An introduction to posterior predictive checks and model misspecification in gravitational-wave astronomy
Publisher: Cambridge University Press (CUP)
Date: 2022
DOI: 10.1017/PASA.2022.24
Abstract: Bayesian inference is a powerful tool in gravitational-wave astronomy. It enables us to deduce the properties of merging compact-object binaries and to determine how these mergers are distributed as a population according to mass, spin, and redshift. As key results are increasingly derived using Bayesian inference, there is increasing scrutiny on Bayesian methods. In this review, we discuss the phenomenon of model misspecification , in which results obtained with Bayesian inference are misleading because of deficiencies in the assumed model(s). Such deficiencies can impede our inferences of the true parameters describing physical systems. They can also reduce our ability to distinguish the ‘best fitting’ model: it can be misleading to say that Model A is preferred over Model B if both models are manifestly poor descriptions of reality. Broadly speaking, there are two ways in which models fail. Firstly, models that fail to adequately describe the data (either the signal or the noise) have misspecified likelihoods. Secondly, population models—designed, for ex le, to describe the distribution of black hole masses—may fail to adequately describe the true population due to a misspecified prior. We recommend tests and checks that are useful for spotting misspecified models using ex les inspired by gravitational-wave astronomy. We include companion python notebooks to illustrate essential concepts.
Limits of Astrophysics with Gravitational-Wave Backgrounds
Publisher: American Physical Society (APS)
Date: 04-08-2016
All-sky, narrowband, gravitational-wave radiometry with folded data
Publisher: American Physical Society (APS)
Date: 03-06-2015
Model exploration in gravitational-wave astronomy with the maximum population likelihood
Publisher: American Physical Society (APS)
Date: 07-04-2023
Measuring eccentricity in binary black hole inspirals with gravitational waves
Publisher: American Physical Society (APS)
Date: 31-10-2018
Prospects for searches for long-duration gravitational-waves without time slides
Publisher: American Physical Society (APS)
Date: 17-08-2015
Validating gravitational-wave detections: The Advanced LIGO hardware injection system
Publisher: American Physical Society (APS)
Date: 27-03-2017
Rotational variation of the linear polarization of the asteroid (3200) Phaethon as evidence for inhomogeneity in its surface properties★
Publisher: Oxford University Press (OUP)
Date: 08-2018
Detecting very long-lived gravitational-wave transients lasting hours to weeks
Publisher: American Physical Society (APS)
Date: 18-05-2015
The minimum and maximum gravitational-wave background from supermassive binary black holes
Publisher: Oxford University Press (OUP)
Date: 23-10-2018
Searching for prompt signatures of nearby core-collapse supernovae by a joint analysis of neutrino and gravitational wave data
Publisher: IOP Publishing
Date: 06-04-2010
GWCloud: A Searchable Repository for the Creation and Curation of Gravitational-wave Inference Results
Publisher: American Astronomical Society
Date: 06-2023
Abstract: There are at present ( 100 ) gravitational-wave candidates from compact binary mergers reported in the astronomical literature. As detector sensitivities are improved, the catalog will swell in size: first to ( 1000 ) events in the A+ era and then to ( 10 6 ) events in the era of third-generation observatories like Cosmic Explorer and the Einstein Telescope. Each event is analyzed using Bayesian inference to determine properties of the source including component masses, spins, tidal parameters, and the distance to the source. These inference products are the fodder for some of the most exciting gravitational-wave science, enabling us to measure the expansion of the universe with standard sirens, to characterize the neutron-star equation of state, and to unveil how and where gravitational-wave sources are assembled. In order to maximize the science from the coming deluge of detections, we introduce GW Cloud , a searchable repository for the creation and curation of gravitational-wave inference products. It is designed with five pillars in mind: uniformity of results, reproducibility of results, stability of results, access to the astronomical community, and efficient use of computing resources. We describe how to use GW Cloud with ex les, which readers can replicate using the companion code to this paper. We describe our long-term vision for GW Cloud .
Building Better Spin Models for Merging Binary Black Holes: Evidence for Nonspinning and Rapidly Spinning Nearly Aligned Subpopulations
Publisher: American Astronomical Society
Date: 29-10-2021
Abstract: Recent work paints a conflicting portrait of the distribution of black hole spins in merging binaries measured with gravitational waves. Some analyses find that a significant fraction of merging binaries contain at least one black hole with a spin tilt ° with respect to the orbital angular momentum vector, which has been interpreted as a signature for dynamical assembly. Other analyses find that the data are consistent with a bimodal population in which some binaries contain black holes with negligible spin while the rest contain black holes with spin vectors preferentially aligned with the orbital angular momentum vector. In this work, we scrutinize models for the distribution of black hole spins to pinpoint possible failure modes in which the model yields a faulty conclusion. We reanalyze data from the second LIGO–Virgo gravitational-wave transient catalog (GWTC-2) using a revised spin model, which allows for a subpopulation of black holes with negligible spins. In agreement with recent results by Roulet et al., we show that the GWTC-2 detections are consistent with two distinct subpopulations. We estimate that 69%–90% (90% credible interval) of merging binaries contain black holes with negligible spin χ ≈ 0. The remaining binaries are part of a second subpopulation in which the spin vectors are preferentially (but not exactly) aligned to the orbital angular momentum. The black holes in this second subpopulation are characterized by spins of χ ∼ 0.5. We suggest that the inferred spin distribution is consistent with the hypothesis that all merging binaries form via the field formation scenario.
An introduction to Bayesian inference in gravitational-wave astronomy: Parameter estimation, model selection, and hierarchical models
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/PASA.2019.2
Abstract: This is an introduction to Bayesian inference with a focus on hierarchical models and hyper-parameters. We write primarily for an audience of Bayesian novices, but we hope to provide useful insights for seasoned veterans as well. Ex les are drawn from gravitational-wave astronomy, though we endeavour for the presentation to be understandable to a broader audience. We begin with a review of the fundamentals: likelihoods, priors, and posteriors. Next, we discuss Bayesian evidence, Bayes factors, odds ratios, and model selection. From there, we describe how posteriors are estimated using s lers such as Markov Chain Monte Carlo algorithms and nested s ling. Finally, we generalise the formalism to discuss hyper-parameters and hierarchical models. We include extensive appendices discussing the creation of credible intervals, Gaussian noise, explicit marginalisation, posterior predictive distributions, and selection effects.
Gravitational-wave astronomy with a physical calibration model
Publisher: American Physical Society (APS)
Date: 18-12-2020
Gravitational-Wave Cosmology across 29 Decades in Frequency
Publisher: American Physical Society (APS)
Date: 31-03-2016
Gravitational waves from Scorpius X-1: A comparison of search methods and prospects for detection with advanced detectors
Publisher: American Physical Society (APS)
Date: 10-07-2015
Related Organisations
California Institute Of Technology
Location: United States of America
Related Funding Activities
Gravitational-wave Astronomy: Detection And Beyond
Start Date: 2015
End Date: 2018
Funder: Australian Research Council
View Funded ActivityARC Centre Of Excellence For Gravitational Wave Discovery
Start Date: 2017
End Date: 2023
Funder: Australian Research Council
View Funded ActivityARC Future Fellowships - Grant ID: FT150100281
Start Date: 06-2016
End Date: 10-2020
Amount: $618,352.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE210100002
Start Date: 09-2021
End Date: 08-2025
Amount: $3,000,000.00
Funder: Australian Research Council
View Funded ActivityARC Centres Of Excellence - Grant ID: CE170100004
Start Date: 04-2017
End Date: 03-2024
Amount: $31,300,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP230103088
Start Date: 2023
End Date: 12-2026
Amount: $460,000.00
Funder: Australian Research Council
View Funded ActivityARC Centres Of Excellence - Grant ID: CE230100016
Start Date: 04-2024
End Date: 03-2031
Amount: $35,000,000.00
Funder: Australian Research Council
View Funded Activity