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Related papers: Pulsar timing arrays: the emerging gravitational-w…

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Multiple pulsar timing array (PTA) collaborations have recently reported the first detection of gravitational waves (GWs) of nanohertz frequencies. The signal is expected to be primarily sourced by inspiralling supermassive black hole…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-13 Gabriela Sato-Polito , Matias Zaldarriaga , Eliot Quataert

Several pulsar timing array (PTA) groups have recently claimed the detection of nanohertz gravitational wave background (GWB), but the origin of this gravitational wave (GW) signal remains unclear. Nanohertz GWs generated by supermassive…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-04 Qing Yang , Xiao Guo , Zhoujian Cao , Xiaoyun Shao , Xi Yuan

The detection of compact binary mergers with sub-solar masses at gravitational-wave observatories could mark the groundbreaking discovery of primordial black holes (PBHs). Concurrently, evidence for a nHz stochastic gravitational wave…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-28 Yann Gouttenoire , Sokratis Trifinopoulos , Miguel Vanvlasselaer

The pulsar timing array (PTA) is a powerful technique for detecting nanohertz gravitational wave backgrounds (GWBs). However, conventional PTAs lack sensitivity to parity violation in the GWB. In this work, we propose a dipole pulsar timing…

General Relativity and Quantum Cosmology · Physics 2026-04-10 Baoyu Xu , Hanyu Jiang , Rong-Gen Cai , Misao Sasaki , Yun-Long Zhang

The circular polarization of the stochastic gravitational wave background (SGWB) is a key observable for characterising the origin of the signal detected by Pulsar Timing Array (PTA) collaborations. Both the astrophysical and the…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-10 N. M. Jiménez Cruz , Ameek Malhotra , Gianmassimo Tasinato , Ivonne Zavala

Pulsar timing array (PTA) provides an excellent opportunity to detect the gravitational waves (GWs) in nanoHertz frequency band. In particular, due to the larger number of "arms" in PTA, it can be used to test gravity by probing the…

General Relativity and Quantum Cosmology · Physics 2019-03-29 Rui Niu , Wen Zhao

Pulsar-timing arrays (PTAs) are seeking gravitational waves from supermassive-black-hole binaries, and there are prospects to complement these searches with stellar-astrometry measurements. Theorists still disagree, however, as to whether…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-19 Selim C. Hotinli , Marc Kamionkowski , Andrew H. Jaffe

Pulsar timing array (PTA) experiments are becoming increasingly sensitive to gravitational waves (GWs) in the nanohertz frequency range, where the main astrophysical sources are supermassive black hole binaries (SMBHBs), which are expected…

High Energy Astrophysical Phenomena · Physics 2021-11-24 Tingting Liu , Sarah J. Vigeland

We discuss the interpretation of the detected signal by Pulsar Timing Array (PTA) observations as a gravitational wave background (GWB) of cosmological origin. We combine NANOGrav 15-years and EPTA-DR2new data sets and confront them against…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-29 Daniel G. Figueroa , Mauro Pieroni , Angelo Ricciardone , Peera Simakachorn

Gravitational waves (GWs) at ultra-low frequencies (${\lesssim 100\,\mathrm{nHz}}$) are key to understanding the assembly and evolution of astrophysical black hole (BH) binaries with masses $\sim 10^{6}-10^{9}\,M_\odot$ at low redshifts.…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-26 Christopher J. Moore , Alberto Vecchio

The stochastic gravitational wave background (SGWB) can be observed in the nanohertz band using a pulsar timing array (PTA). Here a computationally efficient state-space framework is developed for analysing SGWB data, in which the…

Pulsar Timing Arrays are playing a crucial role in the ongoing gravitational wave astronomy revolution. The current evidence for a stochastic gravitational wave background (SGWB) at nHz frequencies offers an opportunity to discover…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-07 Chiara Cecchini , Gabriele Franciolini , Mauro Pieroni

Precision pulsar timing at the level of tens to hundreds of nanoseconds allows detection of nanohertz gravitational waves (GWs) from supermassive binary black holes (SMBBHs) at the cores of merging galaxies and, potentially, from exotic…

Instrumentation and Methods for Astrophysics · Physics 2019-03-25 J. M. Cordes , M. A. McLaughlin

Pulsar timing experiments are reaching sufficient sensitivity to detect a postulated stochastic gravitational wave background generated by merging supermassive black hole systems in the cores of galaxies. We describe the techniques behind…

Astrophysics · Physics 2009-06-23 G. Hobbs

The gravitational waves (GWs) from supermassive binary black holes (BBHs) are long sought by pulsar timing array experiments (PTAs), in the forms of both a stochastic GW background (GWB) and individual sources. The evidence for a GWB was…

High Energy Astrophysical Phenomena · Physics 2024-09-27 Yunfeng Chen , Qingjuan Yu , Youjun Lu

Statistical anisotropy in the nanohertz-frequency gravitational-wave background (GWB) is expected to be detected by pulsar timing arrays (PTAs) in the near future. By developing a frequentist statistical framework that intrinsically…

High Energy Astrophysical Phenomena · Physics 2022-12-14 Nihan Pol , Stephen R. Taylor , Joseph D. Romano

Recently, the Hellings Downs correlation has been observed by different pulsar timing array (PTA) collaborations, such as NANOGrav, European PTA, Parkes PTA, and Chinese PTA. These PTA measurements of the most precise pulsars within the…

High Energy Physics - Phenomenology · Physics 2024-12-02 Jing Yang , Ning Xie , Fa Peng Huang

The astrophysical gravitational wave background in the nanohertz (nHz) band is expected to be primarily composed of the superposition of signals from binaries of supermassive black holes. The spatial discreteness of these sources introduces…

General Relativity and Quantum Cosmology · Physics 2025-08-28 Giulia Cusin , Cyril Pitrou , Martin Pijnenburg , Alberto Sesana

We use the Horizon-AGN cosmological simulation to study the properties of supermassive black hole binaries (MBHBs) contributing most to the gravitational wave background (GWB) signal expected in the pulsar timing array (PTA) band. We…

Observing and timing a group of millisecond pulsars (MSPs) with high rotational stability enables the direct detection of gravitational waves (GWs). The GW signals can be identified from the spatial correlations encoded in the…