N. Cornish
A5006687149- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Black Holes and Theoretical Physics
- Astrophysics and Cosmic Phenomena
- Relativity and Gravitational Theory
- Seismic Waves and Analysis
- Geophysics and Sensor Technology
- High-pressure geophysics and materials
- Advanced Frequency and Time Standards
- Statistical and numerical algorithms
- Computational Physics and Python Applications
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Seismic Imaging and Inversion Techniques
- Particle physics theoretical and experimental studies
- Atomic and Subatomic Physics Research
- Seismology and Earthquake Studies
- Quantum chaos and dynamical systems
- Stellar, planetary, and galactic studies
- Particle Accelerators and Free-Electron Lasers
Montana State University
2016-2025
Campbell Collaboration
2023
Marshall Space Flight Center
2023
California Institute of Technology
2011-2022
University of Glasgow
2017-2021
Observatoire de la Côte d’Azur
2006-2021
Université Côte d'Azur
2020-2021
Centre National de la Recherche Scientifique
2020-2021
Association for Asian Studies
2019
Astrophysique Relativiste, Théories, Expériences, Métrologie, Instrumentation, Signaux
2019
Following the selection of The Gravitational Universe by ESA, and successful flight LISA Pathfinder, Consortium now proposes a 4 year mission in response to ESA's call for missions L3. observatory will be based on three arms with six active laser links, between identical spacecraft triangular formation separated 2.5 million km. is an all-sky monitor offer wide view dynamic cosmos using Waves as new unique messengers unveil Universe. It provides closest ever infant at TeV energy scales, has...
Abstract We report multiple lines of evidence for a stochastic signal that is correlated among 67 pulsars from the 15 yr pulsar timing data set collected by North American Nanohertz Observatory Gravitational Waves. The correlations follow Hellings–Downs pattern expected gravitational-wave background. presence such background with power-law spectrum favored over model only independent noises Bayes factor in excess 10 14 , and this same an uncorrelated common factors 200–1000, depending on...
The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO) is to detect and study gravitational waves (GWs) astrophysical origin. Direct detection GWs holds promise testing general relativity in strong-field regime, providing a new probe exotic objects such as black holes neutron stars uncovering unanticipated astrophysics. LIGO, joint Caltech–MIT project supported by National Science Foundation, operates three multi-kilometer interferometers at two widely separated sites...
The Laser Interferometer Space Antenna (LISA) will open the mHz band of gravitational wave spectrum for exploration. Sensitivity curves are a useful tool surveying types sources that can be detected by LISA mission. Here we describe how sensitivity curve is constructed, and it used to compute signal-to-noise ratio wide range binary systems. We adopt 2018 mission performance requirement design parameters. consider both sky-averaged sensitivities, at particular sky locations. calculations...
The Advanced Laser Interferometer Antenna (ALIA) and the Big Bang Observer (BBO) have been proposed as follow on missions to Space (LISA). Here we study capabilities of these observatories, how they relate science goals missions. We find that in Stereo (ALIAS), our extension ALIA mission, will go considerably further toward meeting ALIA's main scientific goal studying intermediate mass black holes. also compare LISA a related (LISAS). Additionally, initial deployment phase BBO would be...
Abstract We present high-precision timing data over time spans of up to 11 years for 45 millisecond pulsars observed as part the North American Nanohertz Observatory Gravitational Waves (NANOGrav) project, aimed at detecting and characterizing low-frequency gravitational waves. The were with Arecibo and/or Green Bank Telescope frequencies ranging from 327 MHz 2.3 GHz. Most approximately monthly cadence, six high-timing-precision weekly. All widely separated each observing epoch in order fit...
Abstract The 15 yr pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) shows positive evidence presence of a low-frequency gravitational-wave (GW) background. In this paper, we investigate potential cosmological interpretations signal, specifically cosmic inflation, scalar-induced GWs, first-order phase transitions, strings, and domain walls. We find that, with exception stable strings field theory origin, all these models can...
We search for an isotropic stochastic gravitational-wave background (GWB) in the newly released $11$-year dataset from North American Nanohertz Observatory Gravitational Waves (NANOGrav). While we find no significant evidence a GWB, place constraints on GWB population of supermassive black-hole binaries, cosmic strings, and primordial GWB. For first time, that upper limits detection statistics are sensitive to Solar System ephemeris (SSE) model used, SSE errors can mimic signal. developed...
The detection of the Cosmic Microwave Background Radiation (CMB) was one most important cosmological discoveries last century. With development interferometric gravitational wave detectors, we may be in a position to detect equivalent CMB this Gravitational (CGB) is likely isotropic and stochastic, making it difficult distinguish from instrument noise. contribution CGB can isolated by cross-correlating signals two or more independent detectors. Here extend previous studies that considered...
A central challenge in Gravitational Wave Astronomy is identifying weak signals the presence of non-stationary and non-Gaussian noise. The separation gravitational wave from noise requires good models for both. When accurate signal are available, such as binary Neutron star systems, it possible to make robust detection statements even when poorly understood. In contrast, searches "un-modeled" transient strongly impacted by methods used characterize Here we take a Bayesian approach introduce...
We review the expected science performance of New Gravitational-Wave Observatory (NGO, a.k.a. eLISA), a mission under study by European Space Agency for launch in early 2020s. eLISA will survey low-frequency gravitational-wave sky (from 0.1 mHz to 1 Hz), detecting and characterizing broad variety systems events throughout Universe, including coalescences massive black holes brought together galaxy mergers; inspirals stellar-mass compact stars into central galactic holes; several millions...
We compute upper limits on the nanohertz-frequency isotropic stochastic gravitational wave background (GWB) using 9-year data release from North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration. set a GWB supermassive black hole binaries under power law, broken and free spectral coefficient GW spectrum models. place 95\% limit strain amplitude (at frequency of yr$^{-1}$) in law model $A_{\rm gw} < 1.5\times 10^{-15}$. For model, we priors derived simulations...
We searched for an isotropic stochastic gravitational wave background in the second data release of International Pulsar Timing Array, a global collaboration synthesizing decadal-length pulsar-timing campaigns North America, Europe, and Australia. In our reference search power law strain spectrum form $h_c = A(f/1\,\mathrm{yr}^{-1})^{\alpha}$, we found strong evidence spectrally-similar low-frequency process amplitude $A 3.8^{+6.3}_{-2.5}\times10^{-15}$ spectral index $\alpha -0.5 \pm 0.5$,...
The NANOGrav 15-year data set shows evidence for the presence of a low-frequency gravitational-wave background (GWB). While many physical processes can source such gravitational waves, here we analyze signal as coming from population supermassive black hole (SMBH) binaries distributed throughout Universe. We show that astrophysically motivated models SMBH binary populations are able to reproduce both amplitude and shape observed spectrum. multiple model variations GWB spectrum at our current...
We present high-precision timing observations spanning up to nine years for 37 millisecond pulsars monitored with the Green Bank and Arecibo radio telescopes as part of North American Nanohertz Observatory Gravitational Waves (NANOGrav) project. describe observational instrumental setups used collect data, methodology applied calculating pulse times arrival; these include novel methods measuring offsets characterizing low signal-to-noise ratio results. The time arrival data are fit a...
Abstract We present observations and timing analyses of 68 millisecond pulsars (MSPs) comprising the 15 yr data set North American Nanohertz Observatory for Gravitational Waves (NANOGrav). NANOGrav is a pulsar array (PTA) experiment that sensitive to low-frequency gravitational waves (GWs). This NANOGrav’s fifth public release, including both “narrowband” “wideband” time-of-arrival (TOA) measurements corresponding models. have added 21 MSPs extended our baselines by 3 yr, now spanning nearly...
Gravitational wave data from ground-based detectors is dominated by instrument noise. Signals will be comparatively weak, and our understanding of the noise influence detection confidence signal characterization. Mis-modeled can produce large systematic biases in both model selection parameter estimation. Here we introduce a multi-component, variable dimension, parameterized to describe Gaussian-noise power spectrum for gravitational interferometers. Called BayesLine, algorithm models...
Abstract We search for an isotropic stochastic gravitational-wave background (GWB) in the 12.5 yr pulsar-timing data set collected by North American Nanohertz Observatory Gravitational Waves. Our analysis finds strong evidence of a process, modeled as power law, with common amplitude and spectral slope across pulsars. Under our fiducial model, Bayesian posterior f −2/3 power-law spectrum, expressed characteristic GW strain, has median 1.92 × 10 −15 5%–95% quantiles 1.37–2.67 at reference...
We describe updates and improvements to the BayesWave gravitational wave transient analysis pipeline, provide examples of how algorithm is used analyze data from ground-based detectors. models signals in a morphology-independent manner through sum frame functions, such as Morlet-Gabor wavelets or chirplets. instrument noise using combination parametrized Gaussian component non-stationary non-Gaussian transients. Both signal model employ trans-dimensional sampling, with complexity adapting...
Pulsar timing arrays (PTAs) are galactic-scale gravitational wave detectors. Each individual arm, composed of a millisecond pulsar, radio telescope, and kiloparsecs-long path, differs in its properties but, aggregate, can be used to extract low-frequency (GW) signals. We present noise sensitivity analysis accompany the NANOGrav 15-year data release associated papers, along with an in-depth introduction PTA models. As first step our analysis, we characterize each pulsar set three types white...
Abstract Evidence for a low-frequency stochastic gravitational-wave background has recently been reported based on analyses of pulsar timing array data. The most likely source such is population supermassive black hole binaries, the loudest which may be individually detected in these data sets. Here we present search individual binaries NANOGrav 15 yr set. We introduce several new techniques, enhance efficiency and modeling accuracy analysis. uncovered weak evidence two candidate signals,...
The novel data analysis challenges posed by the Laser Interferometer Space Antenna (LISA) arise from overwhelmingly large number of astrophysical sources in measurement band and density with which they are found data. Robust detection characterization numerous gravitational wave LISA can not be done sequentially, but rather through a simultaneous global fit model containing full suite instrumental features present While previous analyses have focused on individual source types isolation,...