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We studied how eccentricity affects the gravitational wave (GW) spectrum from supermassive black hole (SMBH) binaries. We developed a fast and accurate semi-analytic method for computing the GW spectra, the distribution for the spectral…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-16 Juhan Raidal , Juan Urrutia , Ville Vaskonen , Hardi Veermäe

We search for continuous gravitational waves (CGWs) produced by individual super-massive black-hole binaries (SMBHBs) in circular orbits using high-cadence timing observations of PSR J1713$+$0747. We observe this millisecond pulsar using…

In this letter we carry out the first systematic investigation of the expected gravitational wave (GW) background generated by supermassive black hole (SMBH) binaries in the nHz frequency band accessible to pulsar timing arrays (PTAs). We…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 A. Sesana

Pulsar Timing Arrays (PTAs) observations will detect gravitational waves (GWs) from the early inspiral phase of supermassive black hole binaries (SMBHBs) with orbital periods of weeks to years. Current PTA analyses generally assume circular…

General Relativity and Quantum Cosmology · Physics 2025-11-26 Sara Manzini , Stanislav Babak

A compact binary in an eccentric orbit radiates gravitational waves (GWs) at all integer harmonics of its orbital frequency. In this study, we investigate the effect of orbital eccentricity on the expected gravitational background radiation…

Astrophysics · Physics 2009-11-11 Motohiro Enoki , Masahiro Nagashima

Studies have shown that the use of pulsar timing arrays (PTAs) is among the approaches with the highest potential to detect very low-frequency gravitational waves in the near future. Although the capture of gravitational waves (GWs) by PTAs…

Instrumentation and Methods for Astrophysics · Physics 2020-10-13 MengNi Chen , Yuanhong Zhong , Yi Feng , Di Li , Jin Li

Pulsar timing arrays (PTAs) are approaching the sensitivity required to resolve gravitational waves (GWs) from individual supermassive black hole (SMBH) binaries. However, the large uncertainty in source localization will make the…

High Energy Astrophysical Phenomena · Physics 2025-08-26 Niccolo Veronesi , Maria Charisi , Stephen R Taylor , Jessie Runnoe , Daniel J D'Orazio

The recent detection of a common-spectrum stochastic signal by multiple pulsar timing array (PTA) collaborations has provided tentative evidence for a nanohertz (nHz) stochastic gravitational-wave background (SGWB). This signal can be…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-22 Mohit Raj Sah , Suvodip Mukherjee

We probe ultra-low-frequency gravitational waves (GWs) with statistics of spin-down rates of milli-second pulsars (MSPs) by a method proposed in our prevous work (Yonemaru et al. 2016). The considered frequency range is $10^{-12}{\rm Hz}…

High Energy Astrophysical Phenomena · Physics 2019-10-01 Hiroki Kumamoto , Yuya Imasato , Naoyuki Yonemaru , Keitaro Takahashi , Sachiko Kuroyanagi

Ultra-low-frequency gravitational waves (GWs) generated by individual inspiraling supermassive black hole binaries (SMBHBs) at the centers of galaxies may be detected by pulsar timing arrays (PTAs) in the future. These GW signals, which…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-30 Ling-Feng Wang , Yue Shao , Si-Ren Xiao , Jing-Fei Zhang , Xin Zhang

We develop a unified framework for testing gravity beyond General Relativity (GR) with continuous gravitational waves (CWs) from individual supermassive black hole binaries (SMBHBs). These long-lived, nearly monochromatic nanohertz signals…

General Relativity and Quantum Cosmology · Physics 2026-05-08 Qinyuan Zheng , Bjorn Larsen , Ellis Eisenberg , Chiara M. F. Mingarelli

One of the most promising targets for Pulsar Timing Arrays (PTAs) is identifying an individual supermassive black hole binary (SMBHB) out of the population of binaries theorized to produce a gravitational wave background (GWB). In this…

Instrumentation and Methods for Astrophysics · Physics 2026-04-21 Levi Schult , Polina Petrov , Stephen R. Taylor , Nihan Pol , Nima Laal , Maria Charisi , Chung-Pei Ma

While pulsar timing array (PTA) collaborations have reported evidence for a stochastic gravitational wave background (GWB), the detection of continuous gravitational waves (GWs) from a confirmed supermassive black hole binary (SMBHB) would…

Astrophysics of Galaxies · Physics 2025-10-13 Li-Wen Tian , Yan-Chen Bi , Yu-Mei Wu , Qing-Guo Huang

Several pulsar timing array (PTA) experiments such as NANOGrav and PPTA recently reported evidence of a gravitational wave (GW) background at nano-Hz frequency band. This signal can originate from scalar-induced gravitational waves (SIGW)…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-04 Junsong Cang , Yu Gao , Yiming Liu , Sichun Sun

Pulsar timing arrays are sensitive to low-frequency gravitational waves (GWs), which induce correlated changes in millisecond pulsars' timing residuals. PTA collaborations around the world have recently announced evidence of a nanohertz…

High Energy Astrophysical Phenomena · Physics 2024-10-24 Shashwat C. Sardesai , Joseph Simon , Sarah J. Vigeland

Recent results from pulsar timing arrays (PTAs) show evidence for a gravitational wave background (GWB) consistent with a population of unresolved supermassive black hole (SMBH) binaries (BHBs). While the data do not yet constrain the slope…

Astrophysics of Galaxies · Physics 2024-06-12 Federica Fastidio , Alessia Gualandris , Alberto Sesana , Elisa Bortolas , Walter Dehnen

We assess the effects of super-massive black hole (SMBH) environments on the gravitational-wave (GW) signal from binary SMBHs. To date, searches with pulsar timing arrays for GWs from binary SMBHs, in the frequency band $\sim1-100$\,nHz,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 V. Ravi , J. S. B. Wyithe , R. M. Shannon , G. Hobbs , R. N. Manchester

Pulsar timing arrays (PTAs) are designed to detect gravitational waves (GWs) at nHz frequencies. The expected dominant signal is given by the superposition of all waves emitted by the cosmological population of supermassive black hole…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Alberto Sesana

Pulsar timing arrays (PTAs) are searching for nanohertz-frequency gravitational waves (GWs) through cross-correlation of pulse arrival times from a set of radio pulsars. PTAs have relied upon a frequency-shift formula of the pulse, where…

High Energy Astrophysical Phenomena · Physics 2024-07-03 Ryousuke Kubo , Kakeru Yamahira , Hideki Asada