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Related papers: Estimating the gravitational wave background aniso…

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We perform the first search for an isotropic non-tensorial gravitational-wave background (GWB) allowed in general metric theories of gravity in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) 12.5-year data set.…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-28 Zu-Cheng Chen , Chen Yuan , Qing-Guo Huang

By correlating the signals from a pair of gravitational-wave detectors, one can undertake sensitive searches for a stochastic background of gravitational radiation. If the stochastic background is anisotropic, then this correlated signal…

General Relativity and Quantum Cosmology · Physics 2009-12-30 Bruce Allen , Adrian C. Ottewill

We present two simple analytical methods for computing the gravity wave contribution to the cosmic background radiation (CBR) anisotropy in inflationary models; one method uses a time-dependent transfer function, the other method uses an…

Astrophysics · Physics 2009-10-28 Yun Wang

Pulsar timing arrays have found evidence for a low-frequency gravitational wave background (GWB). Assuming the GWB is produced by supermassive black hole binaries (SMBHBs), the next gravitational wave (GW) signals astronomers anticipate are…

High Energy Astrophysical Phenomena · Physics 2024-04-24 Emiko C. Gardiner , Luke Zoltan Kelley , Anna-Malin Lemke , Andrea Mitridate

Many recent works have shown that the angular resolution of ground-based detectors is too poor to characterize the anisotropies of the stochastic gravitational-wave background (SGWB). For this reason, we asked ourselves if a constellation…

General Relativity and Quantum Cosmology · Physics 2023-01-31 Giulia Capurri , Andrea Lapi , Lumen Boco , Carlo Baccigalupi

Unresolved sources of gravitational waves can create a stochastic gravitational wave background (SGWB) which may have intrinsic or extrinsic anisotropies. The angular power spectrum is a well-suited estimator for characterizing diffuse…

General Relativity and Quantum Cosmology · Physics 2024-09-27 Deepali Agarwal , Jishnu Suresh , Sanjit Mitra , Anirban Ain

Identifying the anisotropies in a cosmologically sourced stochastic gravitational wave background (SGWB) would be of significance in shedding light on the nature of primordial inhomogeneities. For example, if SGWB carries isocurvature…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-18 Yanou Cui , Soubhik Kumar , Raman Sundrum , Yuhsin Tsai

Given the recent detection of gravitational waves from individual sources it is almost a certainty that some form of background of gravitational waves will be detected in future. The most promising candidate for such a detection are…

Instrumentation and Methods for Astrophysics · Physics 2019-01-31 A. I. Renzini , C. R. Contaldi

Anisotropic stochastic gravitational wave background (SGWB) serves as a potential probe of the large-scale structure (LSS) of the universe. In this work, we explore the anisotropic SGWB from local ($z < \sim 0.085$) merging stellar mass…

High Energy Astrophysical Phenomena · Physics 2025-07-01 Zhencheng Li , Zhen Jiang , Yun Liu , Xi-Long Fan , Liang Gao , Yun Chen , Tengpeng Xu

Recent findings from several Pulsar Timing Array (PTA) collaborations point to the existence of a Gravitational Wave Background (GWB) at nanohertz frequencies. A key next step towards characterizing this signal and identifying its origin is…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-16 Thomas Konstandin , Anna-Malin Lemke , Andrea Mitridate , Enrico Perboni

The problem of the detection and mapping of a stochastic gravitational wave background (SGWB), either of cosmological or astrophysical origin, bears a strong semblance to the analysis of CMB anisotropy and polarization. The basic statistic…

General Relativity and Quantum Cosmology · Physics 2008-12-18 Sanjit Mitra , Sanjeev Dhurandhar , Tarun Souradeep , Albert Lazzarini , Vuk Mandic , Sukanta Bose , Stefan Ballmer

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

The Cosmological Gravitational Wave Background (CGWB) anisotropies contain valuable information about the physics of the early universe. Given that General Relativity is intrinsically nonlinear, it is important to look beyond first-order…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-29 Alina Mierna , Sabino Matarrese , Nicola Bartolo , Angelo Ricciardone

By listening to gravity in the low frequency band, between 0.1 mHz and 1 Hz, the future space-based gravitational-wave observatory LISA will be able to detect tens of thousands of astrophysical sources from cosmic dawn to the present. The…

General Relativity and Quantum Cosmology · Physics 2019-07-24 Quentin Baghi , Ira Thorpe , Jacob Slutsky , John Baker , Tito Dal Canton , Natalia Korsakova , Nikos Karnesis

We extend the previously described CMB Gibbs sampling framework to allow for exact Bayesian analysis of anisotropic universe models, and apply this method to the 5-year WMAP temperature observations. This involves adding support for…

Astrophysics · Physics 2011-02-11 Nicolaas E. Groeneboom , Hans Kristian Eriksen

We study the possible contribution of a stochastic gravitational wave background to the anisotropy of the cosmic microwave background (CMB) in cold and mixed dark matter (CDM and MDM) models. We test this contribution against recent…

Astrophysics · Physics 2009-10-31 A. Melchiorri , M. V. Sazhin , V. V. Shulga , N. Vittorio

We search for an isotropic stochastic gravitational-wave background (GWB) in the $12.5$-year pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves. Our analysis finds strong evidence of a…

Pulsar timing arrays aim to detect nanohertz-frequency gravitational waves (GWs). A background of GWs modulates pulsar arrival times and manifests as a stochastic process, common to all pulsars, with a signature spatial correlation. Here we…

This article explores the properties (amplitude and shape) of the angular power spectrum of the anisotropies of the astrophysical gravitational wave background (AGWB) focusing on the signatures of the astrophysical models describing…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-18 Giulia Cusin , Irina Dvorkin , Cyril Pitrou , Jean-Philippe Uzan

We consider a search for the anisotropic stochastic gravitational-wave background (SGWB) that decomposes the sky map into its spherical harmonics components in order to obtain estimators of the angular power spectrum. Such a search often…

General Relativity and Quantum Cosmology · Physics 2026-04-21 Erik Floden , Alex Granados , Vuk Mandic