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Gravitational waves are predicted by Einstein's theory of general relativity as well as other theories of gravity. The rotational stability of the fastest pulsars means that timing of an array of these objects can be used to detect and…

Solar and Stellar Astrophysics · Physics 2015-05-28 J. Ellis , M. A. McLaughlin , J. P. W. Verbiest

State-of-the-art searches for gravitational waves (GWs) in pulsar timing array (PTA) datasets model the signal as an isotropic, Gaussian and stationary process described by a power-law. In practice, none of these properties are expected to…

High Energy Astrophysical Phenomena · Physics 2024-03-25 Serena Valtolina , Golam Shaifullah , Anuradha Samajdar , Alberto Sesana

Several observational phenomena suggest that the standard model of cosmology and particle physics requires revision. To address this, we consider the extension of general relativity known as massive gravity (MG). In this Letter, we explore…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-04 Chris Choi , Tina Kahniashvili

In this paper we study the behaviour of gravitational wave background (GWB) generated during inflation in the environment of the noncommutative field approach. From this approach we derive out one additive term, and then we find that the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Yi-Fu Cai , Yun-Song Piao

Gravitational waves (GWs) originating from cosmological sources offer direct insights into the physics of the primordial Universe, the fundamental nature of gravity, and the cosmic expansion of the Universe. In this review paper, we present…

Noncommutative gravity is a natural method of quantizing spacetime by promoting the spacetime coordinates themselves to operators which do not commute. This approach is motivated, for example, from a quantum gravity perspective, among…

General Relativity and Quantum Cosmology · Physics 2020-10-14 Leah Jenks , Kent Yagi , Stephon Alexander

Correlated time-of-arrival measurements by pulsar timing arrays (PTAs) have provided a new means of constraining astrophysical or cosmological models that produce a gravitational wave (GW) background. For this work, we discuss the…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-03 Reginald Christian Bernardo , Seoktae Koh , Gansukh Tumurtushaa

Current searches for signals of departures from the fundamental symmetries of General Relativity using gravitational waves are largely dominated by propagation effects like dispersion and birefringence from highly dynamic sources such as…

General Relativity and Quantum Cosmology · Physics 2023-12-08 Nils A. Nilsson , Christophe Le-Poncin Lafitte

A recent proposal describes space based gravitational wave (GW) detection with optical lattice atomic clocks [Kolkowitz et. al., Phys. Rev. D 94, 124043 (2016)] [1]. Based on their setup, we propose a new measurement method for…

General Relativity and Quantum Cosmology · Physics 2020-05-15 Feifan He , Baocheng Zhang

Using public pulse time-of-arrival data from five pulsar timing arrays (PTAs), we search for a stationary, isotropic, and unpolarized nHz stochastic gravitational-wave background (SGWB). This analysis is more sensitive than previous…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-29 Wang-Wei Yu , Bruce Allen

Large-area sky surveys show that massive galaxies undergo at least one major merger in a Hubble time. Ongoing pulsar timing array (PTA) experiments are aimed at measuring the gravitational wave (GW) emission from binary supermassive black…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 V. Ravi , J. S. B. Wyithe , R. M. Shannon , G. Hobbs

Gravitational waves provide a new probe of the Universe which can reveal a number of cosmological and astrophysical phenomena that cannot be observed by electromagnetic waves. Different frequencies of gravitational waves are detected by…

General Relativity and Quantum Cosmology · Physics 2021-11-08 Jun'ichi Yokoyama

The recent astronomical milestone by the pulsar timing arrays (PTA) has revealed galactic-size gravitational waves (GW) in the form of a stochastic gravitational wave background (SGWB), correlating the radio pulses emitted by millisecond…

General Relativity and Quantum Cosmology · Physics 2024-11-08 Reginald Christian Bernardo , Kin-Wang Ng

Strong evidence for an isotropic, Gaussian gravitational wave background (GWB) has been found by multiple pulsar timing arrays (PTAs). The GWB is expected to be sourced by a finite population of supermassive black hole binaries (SMBHBs)…

General Relativity and Quantum Cosmology · Physics 2026-05-21 William G. Lamb , Jeremy M. Wachter , Andrea Mitridate , Shashwat C. Sardesai , Bence Bécsy , Emily L. Hagen , Stephen R. Taylor , Luke Zoltan Kelley

In the last decade, the use of an ensemble of radio pulsars to constrain the characteristic strain caused by a stochastic gravitational wave background has advanced the cause of detection of very low frequency gravitational waves…

Instrumentation and Methods for Astrophysics · Physics 2013-01-25 Bhal Chandra Joshi

Recently, strong evidence for a gravitational wave background has been reported by collaborations of pulsar timing arrays (PTA). In the framework of scalar-induced gravitational waves (SIGWs), we concurrently investigate the second and…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-28 Sai Wang , Zhi-Chao Zhao , Qing-Hua Zhu

A method is suggested to explore the gravitational wave background (GWB) in the frequency range from $10^{-12}$ to \hbox{$10^{-8}$ Hz}. That method is based on the precise measurements of pulsars' rotational parameters: the influence of the…

Instrumentation and Methods for Astrophysics · Physics 2009-10-08 M. S. Pshirkov

In this study, we investigate the scenario in which the stochastic signal arises from primordial gravitational waves. Within this framework, we consider two distinct possibilities: one in which the pulsar timing arrays (PTAs) signal…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-24 Jun Li , Guanghai Guo , Pengfei Yan

In this paper we ask whether the phenomenon of timing noise long known in electromagnetic pulsar astronomy is likely to be important in gravitational wave (GW) observations of spinning-down neutron stars. We find that timing noise is strong…

General Relativity and Quantum Cosmology · Physics 2009-11-10 D. I. Jones

We study cosmological gravitational waves generated during inflation under the influence of a decaying cosmological "constant", in the Transverse-Traceless (TT) gauge. In our approach we consider a non-perturbative contribution of the…

General Relativity and Quantum Cosmology · Physics 2012-02-27 Reyes Luz Marina , Moreno Claudia , Madriz Aguilar Jose Edgar