Article
Astronomy & Astrophysics
Rossella Gamba, Sebastiano Bernuzzi
Summary: The resonant excitation of f modes in binary neutron star coalescences plays a significant role in the emission of gravitational waves (GWs) during both quasicircular and highly eccentric mergers, providing information about the interior of the stars. Existing models of resonant tides have been validated using perturbative approaches valid at low frequencies, but their validation in the high-frequency regime requires comparisons with numerical relativity (NR) simulations. The comparison between NR simulations and the effective-one-body (EOB) model TEOBResumS with various tidal potentials, including a model for resonant tides, reveals the limitations of tidal models in reproducing NR waveforms and energetics, particularly in the case of highly eccentric mergers.
Article
Astronomy & Astrophysics
Bing-Jyun Tsao, Roland Haas, Antonios Tsokaros
Summary: A new method is proposed to solve the initial condition problem for a binary neutron star system, using source terms to address boundary conditions and achieving convergence through two-dimensional tests and three-dimensional simulations. By comparing the results with an existing solver, the method demonstrates accuracy to approximately 1% and can be applied to other problems with non-smooth solutions like magnetized neutron stars.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
Duncan Neill, David Tsang, Hendrik van Eerten, Geoffrey Ryan, William G. Newton
Summary: Resonant shattering flares (RSFs) are bursts of gamma-rays triggered by tidal resonance of a neutron star (NS) during binary inspiral. By modeling multiple colliding relativistic shells, it is found that the non-thermal gamma-ray emission from these flares could be very bright and a broad-band afterglow may be produced.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Thomas Helfer, Ulrich Sperhake, Robin Croft, Miren Radia, Bo-Xuan Ge, Eugene A. Lim
Summary: This study investigates the head-on collisions of boson stars through numerical simulations and explores the quality of binary initial data obtained from the superposition of single-star spacetimes. The results show that plain superposition of individual boosted boson-star spacetimes can lead to significant unphysical artefacts. A modification of the initial data proposed by Helfer et al in 2019 is effective in overcoming these difficulties for equal-mass binaries. Furthermore, the vulnerability observed in this study may also be present in other exotic compact systems.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Astronomy & Astrophysics
Josu C. Aurrekoetxea, Katy Clough, Eugene A. Lim
Summary: In numerical relativity simulations, a new scheme based on the conformal transverse-traceless decomposition is introduced to solve the Hamiltonian and momentum constraints for the metric variables. Instead of solving the Hamiltonian constraint as a second-order elliptic equation, an algebraic equation is solved for a choice of conformal factor. This method provides rapid convergent solutions for various initial conditions that have not yet been studied in numerical relativity.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Filippo Santoliquido, Michela Mapelli, Nicola Giacobbo, Yann Bouffanais, M. Celeste Artale
Summary: This study evaluates the redshift distribution of binary black hole, black hole-neutron star binary, and binary neutron star mergers, investigating the impact of factors such as star formation rate density, metallicity evolution, and common envelope on merger rates. The results show that the merger rate of binary neutron stars is almost insensitive to metallicity, making them an ideal test bed for constraining uncertain binary evolution processes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Tsevi Mazeh, Simchon Faigler, Dolev Bashi, Sahar Shahaf, Niv Davidson, Matthew Green, Roy Gomel, Dan Maoz, Amitay Sussholz, Subo Dong, Haotong Zhang, Jifeng Liu, Song Wang, Ali Luo, Zheng Zheng, Na'ama Hallakoun, Volker Perdelwitz, David W. Latham, Ignasi Ribas, David Baroch, Juan Carlos Morales, Evangelos Nagel, Nuno C. Santos, David R. Ciardi, Jessie L. Christiansen, Michael B. Lund, Joshua N. Winn
Summary: This article reports a binary system consisting of a normal star and a probable dormant neutron star. Spectral and photometric observations suggest that the companion's mass is likely in the range of 1.1-2.1 solar masses, possibly indicating the presence of a massive white dwarf. However, there is still some ambiguity regarding the certain identification of the dormant neutron star.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Joao Aveiro, Felipe F. Freitas, Marcio Ferreira, Antonio Onofre, Constanca Providencia, Goncalo Goncalves, Jose A. Font
Summary: In this study, the YOLOv5 model is used for detecting binary neutron star coalescence events from gravitational-wave data, achieving high average precision values. The model shows potential for application in first-stage detection alarm pipelines.
Article
Astronomy & Astrophysics
Cecilia Sgalletta, Giuliano Iorio, Michela Mapelli, M. Celeste Artale, Lumen Boco, Debatri Chattopadhyay, Andrea Lapi, Andrea Possenti, Stefano Rinaldi, Mario Spera
Summary: Galactic binary neutron stars (BNSs) provide a unique opportunity to study the evolution of BNSs. By analyzing their properties, such as merger rate, orbital period, eccentricity, and spin period, and using population synthesis models, researchers have identified key factors that best reproduce the observed population of BNSs in our Galaxy. The implementation of radio selection effects is crucial in matching the observed characteristics of Galactic BNSs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Thiago Assumpcao, Leonardo R. Werneck, Terrence Pierre Jacques, Zachariah B. Etienne
Summary: NRPyElliptic is an elliptic solver built within the NRPy+ framework for numerical relativity. Unlike other solvers, it employs a hyperbolic relaxation scheme, making it easier to tweak and extend. It accelerates the relaxation waves and is much faster than the constant wave speed approach. Although slower in setting up initial data, it is very fast in full simulations.
Article
Physics, Multidisciplinary
Z. Sharifi, M. Bigdeli, D. Alvarez-Castillo, E. Nasiri
Summary: The equation of state of neutron star matter is investigated with consideration of kaon condensation, and the impact of this phenomenon on the deformability of neutron stars is assessed through experimental methods. The results suggest that the presence of kaons in the core of neutron stars can soften the equation of state and affect the deformation of neutron stars.
Article
Astronomy & Astrophysics
Plamen G. Krastev, Kiranjyot Gill, V. Ashley Villar, Edo Berger
Summary: Training deep neural networks to identify specific signals and learn an efficient representation of the mapping between gravitational wave signals and their parameters is crucial for real-time detection and inference of gravitational waves. This study demonstrates the ability of artificial neural networks to promptly detect and characterize binary neutron star gravitational-wave signals in real LIGO data, emphasizing the importance of using realistic gravitational-wave detector data in machine learning approaches.
Article
Astronomy & Astrophysics
Christine E. Collins, Andreas Bauswein, Stuart A. Sim, Vimal Vijayan, Gabriel Martinez-Pinedo, Oliver Just, Luke J. Shingles, Markus Kromer
Summary: The detection of GW170817 and its electromagnetic counterpart AT2017gfo has provided valuable constraints for theoretical models of neutron star mergers and nucleosynthesis. Using a Monte Carlo radiative transfer code, the authors simulate synthetic light curves of the dynamical ejecta from a neutron star merger, taking into account neutrino interactions. They find that emission along polar lines of sight is brighter than that along equatorial lines of sight, and the bolometric light curve exhibits a monotonic decline with a shoulder when the ejecta becomes optically thin. The observed color evolution of AT2017gfo is reproduced by the simulation. The addition of a spherically symmetric secular ejecta component enhances the emission, leading to a shift in the shoulder time from 1-2 days to 6-10 days.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Alexander R. Kaltenborn, Michael J. J. Falato, Oleg Korobkin, Irina Sagert, Wesley P. P. Even
Summary: Studying compact-star binaries and their mergers is crucial for determining observable transients. Smoothed particle hydrodynamics (SPH) is an effective numerical technique for studying these mergers due to its excellent conservation properties and ability to represent irregular morphologies. Ensuring regular particle distribution and removing global oscillation modes are essential for accurate simulations. We propose a new relaxation method called halted-pendulum relaxation (HPR) that efficiently removes global oscillation modes and achieves desired density distribution.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Noam Soker
Summary: The study explores a triple-star scenario in which two neutron stars enter a red supergiant star's envelope and spiral towards its core, leading to a CEJSN event. The event is powered by accretion discs and jets, staying luminous for months to years and potentially producing gravitational wave signals. This scenario may help address the issue of r-process nucleosynthesis in the early Universe related to NS-NS mergers.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)