A. S. Bell
A5113599157- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Particle Detector Development and Performance
- Quantum Chromodynamics and Particle Interactions
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Geophysics and Gravity Measurements
- Astrophysics and Cosmic Phenomena
- Neutrino Physics Research
- Computational Physics and Python Applications
- Atomic and Subatomic Physics Research
- Geophysics and Sensor Technology
- Advanced Frequency and Time Standards
- Bladder and Urothelial Cancer Treatments
- Seismic Waves and Analysis
- Radio Astronomy Observations and Technology
- High-pressure geophysics and materials
- Radiation Detection and Scintillator Technologies
- DNA Repair Mechanisms
- Lung Cancer Research Studies
- PARP inhibition in cancer therapy
- Black Holes and Theoretical Physics
University College London
2016-2024
Banner - University Medical Center Phoenix
2024
Banner Health
2024
University of Glasgow
2013-2023
National Institutes of Health
2023
National Institute on Alcohol Abuse and Alcoholism
2023
National and Kapodistrian University of Athens
2018-2022
University Hospitals Bristol and Weston NHS Foundation Trust
2022
University Hospitals Bristol NHS Foundation Trust
2022
The University of Adelaide
2016-2021
On September 14, 2015 at 09:50:45 UTC the two detectors of Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with peak strain 1.0×10(-21). It matches waveform predicted by general relativity for inspiral and merger pair black holes ringdown resulting single hole. was matched-filter signal-to-noise ratio 24 false alarm rate estimated be less than 1 event per 203,000 years,...
We report the observation of a gravitational-wave signal produced by coalescence two stellar-mass black holes. The signal, GW151226, was observed twin detectors Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. initially identified within 70 s an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with network signal-to-noise ratio 13 and significance greater than 5 $\sigma$. persisted in...
On 2017 August 17, the gravitational-wave event GW170817 was observed by Advanced LIGO and Virgo detectors, gamma-ray burst (GRB) GRB 170817A independently Fermi Gamma-ray Burst Monitor, Anticoincidence Shield for Spectrometer International Gamma-Ray Astrophysics Laboratory. The probability of near-simultaneous temporal spatial observation occurring chance is $5.0\times 10^{-8}$. We therefore confirm binary neutron star mergers as a progenitor short GRBs. association provides new insight...
The Advanced LIGO gravitational wave detectors are second generation instruments designed and built for the two observatories in Hanford, WA Livingston, LA. identical design, specialized versions of a Michelson interferometer with 4 km long arms. As initial LIGO, Fabry-Perot cavities used arms to increase interaction time wave, power recycling is effective laser power. Signal has been added improve frequency response. In most sensitive region around 100 Hz, design strain sensitivity factor...
On 17 August 2017, the LIGO and Virgo observatories made first direct detection of gravitational waves from coalescence a neutron star binary system. The this gravitational-wave signal, GW170817, offers novel opportunity to directly probe properties matter at extreme conditions found in interior these stars. initial, minimal-assumption analysis data placed constraints on tidal effects coalescing bodies, which were then translated radii. Here, we expand upon previous analyses by working under...
The LIGO detection of GW150914 provides an unprecedented opportunity to study the two-body motion a compact-object binary in large-velocity, highly nonlinear regime, and witness final merger excitation uniquely relativistic modes gravitational field. We carry out several investigations determine whether is consistent with black-hole general relativity. find that remnant's mass spin, as determined from low-frequency (inspiral) high-frequency (postinspiral) phases signal, are mutually solution...
In 2009-2010, the Laser Interferometer Gravitational-wave Observa- tory (LIGO) operated together with international partners Virgo and GEO600 as a network to search for gravitational waves of astrophysical origin. The sensitiv- ity these detectors was limited by combination noise sources inherent instrumental design its environment, often localized in time or frequency, that couple into gravitational-wave readout. Here we review performance LIGO instruments during this epoch, work done...
On June 8, 2017 at 02:01:16.49 UTC, a gravitational-wave signal from the merger of two stellar-mass black holes was observed by Advanced LIGO detectors with network signal-to-noise ratio 13. This system is lightest hole binary so far observed, component masses $12^{+7}_{-2}\,M_\odot$ and $7^{+2}_{-2}\,M_\odot$ (90% credible intervals). These lie in range measured low-mass X-ray binaries, thus allowing us to compare detected through gravitational waves electromagnetic observations. The...
The second-generation of gravitational-wave detectors are just starting operation, and have already yielding their first detections. Research is now concentrated on how to maximize the scientific potential astronomy. To support this effort, we present here design targets for a new generation detectors, which will be capable observing compact binary sources with high signal-to-noise ratio throughout Universe.
On September 14, 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected a gravitational-wave transient (GW150914); we characterize properties of source and its parameters. The data around time event were analyzed coherently across LIGO network using suite accurate waveform models that describe gravitational waves from compact binary system in general relativity. GW150914 was produced by nearly equal mass black hole masses 36_{-4}^{+5}M_{⊙} 29_{-4}^{+4}M_{⊙}; for each...
The first observational run of the Advanced LIGO detectors, from September 12, 2015 to January 19, 2016, saw detections gravitational waves binary black hole mergers. In this paper we present full results a search for merger signals with total masses up $100 M_\odot$ and detailed implications our observations these systems. Our search, based on general-relativistic models wave systems, unambiguously identified two signals, GW150914 GW151226, significance greater than $5\sigma$ over observing...
We present results on the mass, spin, and redshift distributions with phenomenological population models using ten binary black hole mergers detected in first second observing runs completed by Advanced LIGO Virgo. constrain properties of (BBH) mass spectrum a range parameterizations BBH spin distributions. find that distribution more massive such binaries is well approximated no than 1% holes $45\,M_\odot$, power law index $\alpha = {1.3}^{+1.4}_{-1.7}$ (90% credibility). also show BBHs are...
The discovery of the gravitational-wave source GW150914 with Advanced LIGO detectors provides first observational evidence for existence binary black-hole systems that inspiral and merge within age Universe. Such mergers have been predicted in two main types formation models, involving isolated binaries galactic fields or dynamical interactions young old dense stellar environments. measured masses robustly demonstrate relatively "heavy" black holes ($\gtrsim 25\, M_\odot$) can form nature....
The detection of gravitational waves by Advanced LIGO and Virgo provides an opportunity to test general relativity in a regime that is inaccessible traditional astronomical observations laboratory tests. We present four tests the consistency data with binary black hole waveforms predicted relativity. One subtracts best-fit waveform from checks residual detector noise. second low- high-frequency parts observed signals. third phenomenological deviations introduced model (including...
Following a major upgrade, the two advanced detectors of Laser Interferometer Gravitational-wave Observatory (LIGO) held their first observation run between September 2015 and January 2016. With strain sensitivity 10^{-23}/sqrt[Hz] at 100 Hz, product observable volume measurement time exceeded that all previous runs within 16 days coincident observation. On 14, 2015, Advanced LIGO observed transient gravitational-wave signal determined to be coalescence black holes [B. P. Abbott et al.,...
On 2019 April 25, the LIGO Livingston detector observed a compact binary coalescence with signal-to-noise ratio 12.9. The Virgo was also taking data that did not contribute to detection due low ratio, but were used for subsequent parameter estimation. 90% credible intervals component masses range from 1.12 2.52 $M_{\odot}$ (1.45 1.88 if we restrict dimensionless spin magnitudes be smaller than 0.05). These mass parameters are consistent individual components being neutron stars. However,...
We report the observation of gravitational waves from a binary-black-hole coalescence during first two weeks LIGO's and Virgo's third observing run. The signal was recorded on April 12, 2019 at 05:30:44 UTC with network signal-to-noise ratio 19. binary is different observations runs most notably due to its asymmetric masses: ~30 solar mass black hole merged ~8 companion. more massive rotated dimensionless spin magnitude between 0.22 0.60 (90% probability). Asymmetric systems are predicted...
Abstract We report the observation of a compact binary coalescence involving 22.2–24.3 M ⊙ black hole and object with mass 2.50–2.67 (all measurements quoted at 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s Virgo’s third observing run on 2019 August 14 21:10:39 UTC has signal-to-noise ratio 25 in three-detector network. source localized to 18.5 deg 2 distance Mpc; no electromagnetic counterpart been confirmed date. most unequal yet measured...
The LIGO detection of the gravitational wave transient GW150914, from inspiral and merger two black holes with masses ≳30M⊙, suggests a population binary relatively high mass. This observation implies that stochastic gravitational-wave background holes, created incoherent superposition all merging binaries in Universe, could be higher than previously expected. Using properties we estimate energy density such holes. In most sensitive part Advanced Virgo band for backgrounds (near 25 Hz),...
On 14 September 2015, a gravitational wave signal from coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes transient noise backgrounds used to determine significance of event (designated GW150914) and presents results investigations into potential correlated or uncorrelated sources in detectors around time event. The were operating nominally at GW150914. We have ruled out environmental influences non-Gaussian instrument either detector as...
A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given name GW150914, is described detail elsewhere. By prior arrangement, preliminary estimates of time, significance, sky location event were shared with 63 teams observers covering radio, optical, near-infrared, X-ray, gamma-ray wavelengths ground- space-based...