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We investigate a novel probe of spatial geometry of the Universe through the observation of gravitational waves (GWs) induced by first order curvature perturbations. The existence of spatial curvature leaves imprints on the gravitational…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-18 Utkarsh Kumar , Udaykrishna Thattarampilly , Pankaj Chaturvedi

The coalescence of a binary black hole can be accompanied by a large gravitational recoil due to anisotropic emission of gravitational waves. A recoiling supermassive black hole (SBH) can subsequently undergo long-lived oscillations in the…

Astrophysics of Galaxies · Physics 2014-10-27 D. Lena , A. Robinson , A. Marconi , D. J. Axon , A. Capetti , D. Merritt , D. Batcheldor

The main aim of the present work is to demonstrate that the analogue gravity phenomena are not an artifact of linear perturbation, rather gravity-like effects emerge through the non linear higher order perturbation of transonic fluid as…

General Relativity and Quantum Cosmology · Physics 2026-05-11 Rohit Ghosh , Souvik Ghose , Biplab Raychaudhuri , Apashanka Das , Tapas K. Das

The nonlinear theory of two-dimensional ion-acoustic (IA) solitary waves and shocks (SWS) is revisited in a dissipative quantum plasma. The effects of dispersion, caused by the charge separation of electrons and ions and the quantum force…

Plasma Physics · Physics 2015-06-23 A. P. Misra , B. Sahu

Radio images of the Galactic Center supermassive black hole, Sagittarius A* (Sgr A*), are dominated by interstellar scattering. Previous studies of Sgr A* have adopted an anisotropic Gaussian model for both the intrinsic source and the…

We show that the inclusion of an axion-like effective potential in the construction of a self-gravitating system made of scalar fields leads to a decrease on its compactness when the value of the self-interaction coupling constant is…

Cosmology and Nongalactic Astrophysics · Physics 2011-03-23 J. Barranco , A. Bernal

Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We have analyzed a comprehensive submillimeter (including new observations simultaneous with…

We study the self-consistent, linear response of a galactic disc to vertical perturbations as induced say by a tidal interaction. We calculate the self-gravitational potential corresponding to a non-axisymmetric, self-consistent density…

Astrophysics · Physics 2009-11-11 Kanak Saha , Chanda J. Jog

Gravitational waves from precessing binary black holes exhibit new features that are absent in non-precessionary systems. All current waveform models take into account only the modulation of the signal due to precession. In this letter, we…

General Relativity and Quantum Cosmology · Physics 2022-12-22 Cheng Zhang , Wen-Biao Han , Shu-Cheng Yang

We consider gravitational waves emitted by various populations of compact binaries at cosmological distances. We use population synthesis models to characterize the properties of double neutron stars, double black holes and double white…

Astrophysical compact objects are usually studied using a perfect fluid model. However, in astrophysical processes out-of-equilibrium, dissipative effects become important to describe the dynamics of the system. In this work, we obtain…

General Relativity and Quantum Cosmology · Physics 2025-08-05 David Díaz-Guerra , Conrado Albertus , Prasanta Char , M. Ángeles Pérez-García

The NANOGrav Collaboration has recently announced evidence for nHz gravitational waves (GWs), in the form of a Hellings-Downs angular correlation in the common-spectrum process that had been observed previously by them and other Pulsar…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-15 John Ellis , Malcolm Fairbairn , Gert Hütsi , Juhan Raidal , Juan Urrutia , Ville Vaskonen , Hardi Veermäe

We investigate scalar-induced stochastic gravitational waves from adiabatic curvature perturbations sourced by a spectator field via the modulated reheating mechanism. We consider a spectator scalar with Higgs-like couplings and inflaton…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-30 Michele Benaco , Dimitrios Karamitros , Sami Nurmi , Kimmo Tuominen

We derive a viscosity from gravitational instability in self-gravitating accretion disks, which has the required properties to account for the observed fast formation of the first super-massive black holes in highly redshifted quasars and…

Astrophysics · Physics 2009-11-11 Wolfgang J. Duschl , Markward Britsch

The discovery of radio pulsars (PSRs) around the supermassive black hole (SMBH) in our Galactic Center (GC), Sagittarius A* (Sgr A*), will have significant implications for tests of gravity. In this paper, we predict restrictions on the…

High Energy Astrophysical Phenomena · Physics 2022-11-28 Yiming Dong , Lijing Shao , Zexin Hu , Xueli Miao , Ziming Wang

The compact radio source Sagittarius A (Sgr A) at the centre of our Galaxy harbours a supermassive black hole, whose mass has been measured from stellar orbital motions. Sgr A is therefore the nearest laboratory where super-massive black…

High Energy Astrophysical Phenomena · Physics 2009-03-24 U. Kostic , A. Cadez , M. Calvani , A. Gomboc

In June 2023, multiple pulsar timing array collaborations provided evidence for the existence of a stochastic gravitational wave background. Scalar induced gravitational waves (SIGWs), as one of the most likely sources of stochastic…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-07 Jing-Zhi Zhou , Yu-Ting Kuang , Zhe Chang , H. Lü

Galactic nuclei are densely populated by stellar mass compact objects such as black holes and neutron stars. Bound, highly eccentric binaries form as a result of gravitational wave (GW) losses during close flybys between these objects. We…

Cosmology and Nongalactic Astrophysics · Physics 2012-07-10 Bence Kocsis , Janna Levin

The advent of gravitational wave (GW) and multi-messenger astronomy has stimulated the research on the formation mechanisms of binary black holes (BBHs) observed by LIGO/Virgo. In literature, the progenitors of these BBHs could be…

General Relativity and Quantum Cosmology · Physics 2025-03-28 Zu-Cheng Chen , Fan Huang , Qing-Guo Huang

We study gravitational absorption effects using effective on-shell scattering amplitudes. We develop an in-in probability-based framework involving plane- and partial-wave coherent states for the incoming wave to describe the interaction of…

High Energy Physics - Theory · Physics 2023-12-14 Rafael Aoude , Alexander Ochirov