scholarly journals Aligned-spin neutron-star–black-hole waveform model based on the effective-one-body approach and numerical-relativity simulations

2020 ◽  
Vol 102 (4) ◽  
Author(s):  
Andrew Matas ◽  
Tim Dietrich ◽  
Alessandra Buonanno ◽  
Tanja Hinderer ◽  
Michael Pürrer ◽  
...  
2019 ◽  
Vol 69 (1) ◽  
pp. 41-64 ◽  
Author(s):  
Masaru Shibata ◽  
Kenta Hotokezaka

Mergers of binary neutron stars and black hole–neutron star binaries are among the most promising sources for ground-based gravitational-wave (GW) detectors and are also high-energy astrophysical phenomena, as illustrated by the observations of GWs and electromagnetic (EM) waves in the event of GW170817. Mergers of these neutron star binaries are also the most promising sites for r-process nucleosynthesis. Numerical simulation in full general relativity (numerical relativity) is a unique approach to the theoretical prediction of the merger process, GWs emitted, mass ejection process, and resulting EM emission. We summarize the current understanding of the processes of neutron star mergers and subsequent mass ejection based on the results of the latest numerical-relativity simulations. We emphasize that the predictions of the numerical-relativity simulations agree broadly with the optical and IR observations of GW170817.


Author(s):  
ZACHARIAH B. ETIENNE ◽  
YUK TUNG LIU ◽  
VASILEIOS PASCHALIDIS ◽  
STUART L. SHAPIRO

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
Koutarou Kyutoku ◽  
Masaru Shibata ◽  
Keisuke Taniguchi

AbstractWe review the current status of general relativistic studies for coalescences of black hole–neutron star binaries. First, high-precision computations of black hole–neutron star binaries in quasiequilibrium circular orbits are summarized, focusing on the quasiequilibrium sequences and the mass-shedding limit. Next, the current status of numerical-relativity simulations for the merger of black hole–neutron star binaries is described. We summarize our understanding for the merger process, tidal disruption and its criterion, properties of the merger remnant and ejected material, gravitational waveforms, and gravitational-wave spectra. We also discuss expected electromagnetic counterparts to black hole–neutron star coalescences.


2021 ◽  
Vol 502 (1) ◽  
pp. L72-L78
Author(s):  
K Mohamed ◽  
E Sonbas ◽  
K S Dhuga ◽  
E Göğüş ◽  
A Tuncer ◽  
...  

ABSTRACT Similar to black hole X-ray binary transients, hysteresis-like state transitions are also seen in some neutron-star X-ray binaries. Using a method based on wavelets and light curves constructed from archival Rossi X-ray Timing Explorer observations, we extract a minimal timescale over the complete range of transitions for 4U 1608-52 during the 2002 and 2007 outbursts and the 1999 and 2000 outbursts for Aql X-1. We present evidence for a strong positive correlation between this minimal timescale and a similar timescale extracted from the corresponding power spectra of these sources.


2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Francois Foucart ◽  
Alexander Chernoglazov ◽  
Michael Boyle ◽  
Tanja Hinderer ◽  
Max Miller ◽  
...  

Author(s):  
R Pattnaik ◽  
K Sharma ◽  
K Alabarta ◽  
D Altamirano ◽  
M Chakraborty ◽  
...  

Abstract Low Mass X-ray binaries (LMXBs) are binary systems where one of the components is either a black hole or a neutron star and the other is a less massive star. It is challenging to unambiguously determine whether a LMXB hosts a black hole or a neutron star. In the last few decades, multiple observational works have tried, with different levels of success, to address this problem. In this paper, we explore the use of machine learning to tackle this observational challenge. We train a random forest classifier to identify the type of compact object using the energy spectrum in the energy range 5-25 keV obtained from the Rossi X-ray Timing Explorer archive. We report an average accuracy of 87±13% in classifying the spectra of LMXB sources. We further use the trained model for predicting the classes for LMXB systems with unknown or ambiguous classification. With the ever-increasing volume of astronomical data in the X-ray domain from present and upcoming missions (e.g., SWIFT, XMM-Newton, XARM, ATHENA, NICER), such methods can be extremely useful for faster and robust classification of X-ray sources and can also be deployed as part of the data reduction pipeline.


2015 ◽  
Vol 91 (12) ◽  
Author(s):  
Tim Dietrich ◽  
Sebastiano Bernuzzi ◽  
Maximiliano Ujevic ◽  
Bernd Brügmann

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