A5070606810- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Astrophysical Phenomena and Observations
- Cosmology and Gravitation Theories
- Geophysics and Sensor Technology
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Seismic Waves and Analysis
- Advanced Frequency and Time Standards
- High-pressure geophysics and materials
- Atomic and Subatomic Physics Research
- Statistical and numerical algorithms
- Astronomical Observations and Instrumentation
- Cold Atom Physics and Bose-Einstein Condensates
- Seismology and Earthquake Studies
- Computational Physics and Python Applications
- Black Holes and Theoretical Physics
- Magnetic confinement fusion research
- Radiomics and Machine Learning in Medical Imaging
- GNSS positioning and interference
- Seismic Imaging and Inversion Techniques
- Superconducting Materials and Applications
- Stellar, planetary, and galactic studies
- Inertial Sensor and Navigation
Lancaster University
2020-2024
University of Cambridge
2023-2024
Lancaster University Ghana
2024
University of Glasgow
2014-2023
Goddard Space Flight Center
2014
California Institute of Technology
2011
Cardiff University
2011
Carleton College
2011
Andrews University
2011
Australian National University
2011
Bayesian parameter estimation is fast becoming the language of gravitational-wave astronomy. It method by which data used to infer sources' astrophysical properties. We introduce a user-friendly inference library for astronomy, Bilby. This python code provides expert-level infrastructure with straightforward syntax and tools that facilitate use beginners. allows users perform accurate reliable on both real, freely-available from LIGO/Virgo, simulated data. provide suite examples analysis...
The Advanced LIGO and Virgo gravitational wave (GW) detectors will begin operation in the coming years, with compact binary coalescence events a likely source for first detections. waveforms emitted directly encode information about sources, including masses spins of objects. Recovering physical parameters sources from GW observations is key analysis task. This work describes LALInference software library Bayesian parameter estimation signals, which builds on several previous methods to...
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, number observations is increasing rapidly as detector sensitivity improves. To extract information observed signals, it imperative to have fast, flexible, scalable inference techniques. In previous paper, we introduced bilby: modular user-friendly Bayesian library adapted...
The direct detection of gravitational waves provides the opportunity to measure fundamental aspects gravity which have never been directly probed before, including polarization waves. In context searches for continuous from known pulsars, we present novel methods detect signals any content, modes and place upper limits on amplitude nontensorial components. This will allow us obtain new model-independent, dynamical constraints deviations general relativity. We test this framework multiple...
The GEO 600 gravitational wave detector uses advanced technologies including signal recycling and monolithic fused-silica suspensions to achieve a sensitivity close the kilometre scale LIGO VIRGO detectors. As soon as design of is reached, will be operated part worldwide network acquire data scientific interest. limited infrastructure at site does not allow for major upgrade detector. Hence collaboration decided improve by small sequential upgrades some which tested in prototypes first....
Of all the large interferometric gravitational-wave detectors, German/British project GEO600 is only one which uses dual recycling. During four weeks of international S4 data-taking run it reached an instrumental duty cycle 97% with a peak sensitivity 7 × 10−22 Hz−1/2 at 1 kHz. This paper describes status during and improvements thereafter.
We describe a search underway for periodic gravitational waves from the central compact object in supernova remnant Cassiopeia A. The is youngest likely neutron star Galaxy. Its position well known, but does not pulse any electromagnetic radiation band and thus presents challenge searching parameter space of frequency derivatives. estimate that fully coherent can, with reasonable amount time on computing cluster, achieve sensitivity at which it theoretically possible (though likely) to...
The direct detection of gravitational waves with the next generation detectors, like Advanced LIGO, provides opportunity to measure deviations from predictions General Relativity. One such departure would be existence alternative polarizations. To these, we study a single detector measurement continuous wave triaxial pulsar source. We develop methods detect signals any polarization content and distinguish between them in model independent way. present LIGO S5 sensitivity estimates for 115 pulsars.
The problem of reconstructing the sky position compact binary coalescences detected via gravitational waves is a central one for future observations with ground-based network gravitational-wave laser interferometers, such as Advanced LIGO and Virgo. Different techniques localization have been independently developed. They can be divided in two broad categories: fully coherent Bayesian techniques, which are high latency aimed at in-depth studies all parameters source, including position,...
Hardware injections are simulated gravitational-wave signals added to the Laser Interferometer Gravitational-wave Observatory (LIGO). The detectors' test masses physically displaced by an actuator in order simulate effects of a gravitational wave. signal initiates control-system response which mimics that true This provides end-to-end LIGO's ability observe waves. analyses used detect and characterize exercised with hardware injections. By looking for discrepancies between injected recovered...
The GEO 600 laser interferometer with m armlength is currently being commissioned as a part of worldwide network gravitational wave detectors. Due to the use advanced technologies such signal recycling and multiple pendulum suspensions monolithic last stage anticipated sensitivity close initial km baseline This paper describes status detector November 2003 special emphasis on its performance during first serious data-taking periods experimental challenges encountered commissioning...
Since December 2003, the gravitational-wave detector GEO 600 has routinely operated in dual recycled mode, using a lock acquisition scheme based on detection of optical sideband power at dark port. With locking very robustly, current commissioning work is entirely dedicated to sensitivity improvements. We give brief overview detector, implementation recycling, and summarize recent regarding increase sensitivity.
The Mock LISA data challenges are a program to demonstrate data-analysis capabilities and encourage their development. Each round of consists several sets containing simulated instrument noise gravitational waves from sources undisclosed parameters. Participants asked analyze the report maximum information about source being released in rounds increasing complexity realism: here we present results Challenge 2, issued Jan 2007, which successfully demonstrated recovery signals nonspinning...
Neutron stars spin down over time due to a number of energy-loss processes. We provide tantalizing population-based evidence that millisecond pulsars (MSPs) have minimum ellipticity $\epsilon\approx10^{-9}$ around their axis and that, consequently, some mostly through gravitational-wave emission. discuss the implications such in terms internal magnetic field strengths nuclear matter composition neutron show it would result Advanced LIGO Virgo detectors, or upgrades, detecting gravitational...
Rapidly rotating neutron stars are promising sources of continuous gravitational wave radiation for the LIGO and Virgo interferometers. The majority in our galaxy have not been identified with electromagnetic observations. All-sky searches isolated offer potential to detect waves from these unidentified sources. parameter space blind all-sky searches, which also cover a large range frequencies frequency derivatives, presents significant computational challenge. Different methods designed...
Gravitational waves (GWs) can offer a novel window into the structure and dynamics of neutron stars. Here we present first search for long-duration quasi-monochromatic GW transients triggered by pulsar glitches. We focus on two glitches observed in radio timing Vela (PSR J0835-4510) 12 December 2016 Crab J0534+2200) 27 March 2017, during Advanced LIGO second observing run (O2). assume frequency lies within narrow band around twice spin as known from observatons. Using fully-coherent...
The excitation of quadrupolar quasinormal modes in a neutron star leads to the emission short, distinctive, burst gravitational radiation form decaying sinusoid or ``ring-down.'' We present Bayesian analysis method which incorporates relevant prior information about source and known instrumental artifacts conduct robust search for wave associated with pulsar glitches soft $\ensuremath{\gamma}$-ray repeater flares. Instrumental transients are modeled as sine-Gaussian their evidence, marginal...
The Mock LISA Data Challenges (MLDCs) have the dual purpose of fostering development data analysis tools and capabilities, demonstrating technical readiness already achieved by gravitational-wave community in distilling a rich science payoff from output. first round MLDCs has just been completed: nine challenges consisting sets containing simulated signals produced either galactic binaries or massive black hole embedded instrumental noise were released June 2006 with deadline for submission...
Several past searches for gravitational waves from a selection of known pulsars have been performed with data the science runs Laser Inferometer Gravitational-wave Observatory (LIGO) wave detectors. So far these lead to no detection, but upper limits on amplitudes set. Here we study our intrinsic ability detect, and estimate amplitude non-accreting pulsars. Using spin-down emission as guide examine that would be required observe future detectors (Advanced LIGO, Advanced Virgo Einstein...
We investigate a method to incorporate signal models that allow an additional frequency harmonic in searches for gravitational waves from spinning neutron stars. assume emission is given by the general triaxial non-aligned model of Jones, whose waveform under certain conditions reduces biaxial precessing star, or simple rigidly rotating aligned star. The and can produce at both star's rotation ($f$) $2f$, whilst latter only emits $2f$. have studied parameter estimation using set physical...
We present a Bayesian-odds-ratio-based algorithm for detecting stellar flares in light-curve data. assume are described by model which there is rapid rise with half-Gaussian profile, followed an exponential decay. Our signal also contains polynomial background required to fit underlying variations the data, could otherwise partially mimic flare. characterize false alarm probability and efficiency of this method under assumption that any unmodelled noise data Gaussian, compare it simpler...
We present a method for assigning statistical significance to detection candidates in targeted searches continuous gravitational waves from known pulsars, without assuming the detector noise is Gaussian and stationary. take advantage of expected Doppler phase modulation signal induced by Earth's orbital motion, as well amplitude spin, effectively blind search real astrophysical signals given location sky. use this "sky-shifting" produce large number noise-only data realizations empirically...