scholarly journals Upper limits on persistent gravitational waves using folded data and the full covariance matrix from Advanced LIGO’s first two observing runs

2021 ◽  
Vol 104 (12) ◽  
Author(s):  
Deepali Agarwal ◽  
Jishnu Suresh ◽  
Sanjit Mitra ◽  
Anirban Ain
Keyword(s):  
Gravitational Waves ◽  
Covariance Matrix ◽  
Upper Limits ◽  
Full Covariance Matrix

scholarly journals Upper Limits on a Stochastic Background of Gravitational Waves

2005 ◽  
Vol 95 (22) ◽  
Author(s):  
B. Abbott ◽  
R. Abbott ◽  
R. Adhikari ◽  
J. Agresti ◽  
P. Ajith ◽  
...  
Keyword(s):  
Gravitational Waves ◽  
Stochastic Background ◽  
Upper Limits

scholarly journals Multivariate Ensemble Sensitivity Analysis for Super Typhoon Haiyan (2013)

2019 ◽  
Vol 147 (9) ◽  
pp. 3467-3480 ◽  
Author(s):  
Sijing Ren ◽  
Lili Lei ◽  
Zhe-Min Tan ◽  
Yi Zhang
Keyword(s):  
Sensitivity Analysis ◽  
High Resolution ◽  
Covariance Matrix ◽  
Multivariate Regression ◽  
Ensemble Forecast ◽  
Initial Condition ◽  
Maximum Wind ◽  
Diagonal Approximation ◽  
Low Levels ◽  
Full Covariance Matrix

Abstract Ensemble sensitivity is often a diagonal approximation to the multivariate regression, leading to a simple univariate regression. Comparatively, the multivariate ensemble sensitivity retains the full covariance matrix when computing the multivariate regression. The performances of both univariate and multivariate ensemble sensitivities in multiscale flows have not been thoroughly examined, and the demonstration of the latter in realistic applications has been sparse. A high-resolution ensemble forecast of Typhoon Haiyan (2013) is used to examine the performances of the two ensemble sensitivities. Compared to the multivariate sensitivity, the univariate sensitivity overestimates the forecast metric, especially at higher levels. To increase the predicted Haiyan’s intensity, multivariate ensemble sensitivity gives initial perturbations characterized by a warming area around the center of the storm, an increased moisture area around the eyewall, a stronger primary circulation around the radius of maximum wind, and stronger inflow at low levels and stronger outflow at high levels. Perturbed initial condition experiments verify that the predicted response from the multivariate sensitivity is more accurate than that from the univariate sensitivity. Therefore, the ability of multivariate sensitivity to provide more accurate predicted responses than the univariate sensitivity has been demonstrated in a realistic multiscale flow application.

scholarly journals First all-sky upper limits from LIGO on the strength of periodic gravitational waves using the Hough transform

2005 ◽  
Vol 72 (10) ◽  
Author(s):  
B. Abbott ◽  
R. Abbott ◽  
R. Adhikari ◽  
A. Ageev ◽  
J. Agresti ◽  
...  
Keyword(s):  
Gravitational Waves ◽  
Hough Transform ◽  
Upper Limits

scholarly journals Constraints from LIGO O3 Data on Gravitational-wave Emission Due to R-modes in the Glitching Pulsar PSR J0537–6910

2021 ◽  
Vol 922 (1) ◽  
pp. 71
Author(s):  
R. Abbott ◽  
T. D. Abbott ◽  
S. Abraham ◽  
F. Acernese ◽  
K. Ackley ◽  
...  
Keyword(s):  
Energy Conservation ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Theoretical Models ◽  
X Ray ◽  
Spin Evolution ◽  
Upper Limits ◽  
Wave Emission ◽  
Using Data

Abstract We present a search for continuous gravitational-wave emission due to r-modes in the pulsar PSR J0537–6910 using data from the LIGO–Virgo Collaboration observing run O3. PSR J0537–6910 is a young energetic X-ray pulsar and is the most frequent glitcher known. The inter-glitch braking index of the pulsar suggests that gravitational-wave emission due to r-mode oscillations may play an important role in the spin evolution of this pulsar. Theoretical models confirm this possibility and predict emission at a level that can be probed by ground-based detectors. In order to explore this scenario, we search for r-mode emission in the epochs between glitches by using a contemporaneous timing ephemeris obtained from NICER data. We do not detect any signals in the theoretically expected band of 86–97 Hz, and report upper limits on the amplitude of the gravitational waves. Our results improve on previous amplitude upper limits from r-modes in J0537-6910 by a factor of up to 3 and place stringent constraints on theoretical models for r-mode-driven spin-down in PSR J0537–6910, especially for higher frequencies at which our results reach below the spin-down limit defined by energy conservation.

scholarly journals Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

2004 ◽  
Vol 21 (5) ◽  
pp. S671-S676 ◽  
Author(s):  
B Allen ◽  
G Woan ◽  
(for the LIGO Scientific Collaboration): ◽  
B Abbott ◽  
R Abbott ◽  
...  
Keyword(s):  
Gravitational Waves ◽  
Upper Limits

scholarly journals Pulsars Probe the Low-Frequency Gravitational Sky: Pulsar Timing Arrays Basics and Recent Results

2018 ◽  
Vol 35 ◽  
Author(s):  
Caterina Tiburzi
Keyword(s):  
Gravitational Waves ◽  
Galaxy Formation ◽  
Low Frequency ◽  
Radio Telescopes ◽  
Detection Algorithms ◽  
Pulsar Timing ◽  
Upper Limits ◽  
New Generation ◽  
Timing Models ◽  
Pulsar Timing Array

AbstractPulsar Timing Array experiments exploit the clock-like behaviour of an array of millisecond pulsars, with the goal of detecting low-frequency gravitational waves. Pulsar Timing Array experiments have been in operation over the last decade, led by groups in Europe, Australia, and North America. These experiments use the most sensitive radio telescopes in the world, extremely precise pulsar timing models and sophisticated detection algorithms to increase the sensitivity of Pulsar Timing Arrays. No detection of gravitational waves has been made to date with this technique, but Pulsar Timing Array upper limits already contributed to rule out some models of galaxy formation. Moreover, a new generation of radio telescopes, such as the Five hundred metre Aperture Spherical Telescope and, in particular, the Square Kilometre Array, will offer a significant improvement to the Pulsar Timing Array sensitivity. In this article, we review the basic concepts of Pulsar Timing Array experiments, and discuss the latest results from the established Pulsar Timing Array collaborations.

scholarly journals Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-based Cross-correlation Search in Advanced LIGO Data

2017 ◽  
Vol 847 (1) ◽  
pp. 47 ◽  
Author(s):  
B. P. Abbott ◽  
R. Abbott ◽  
T. D. Abbott ◽  
F. Acernese ◽  
K. Ackley ◽  
...  
Keyword(s):  
Gravitational Waves ◽  
Cross Correlation ◽  
Model Based ◽  
Upper Limits ◽  
Correlation Search
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