BLACK HOLE–NEUTRON STAR COALESCING BINARIES

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1241-1248
Author(s):  
V. FERRARI ◽  
L. GUALTIERI ◽  
F. PANNARALE
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Equations Of State ◽  
Cutoff Frequency ◽  
Tidal Interactions ◽  
Stable Circular Orbit ◽  
Innermost Stable Circular Orbit ◽  
Laser Interferometers

Coalescing black hole–neutron star binaries have been invoked as possible progenitors of short gamma-ray bursts and are also among the most promising gravitational wave sources to be detected by ground-based laser interferometers. When the star is disrupted by tidal interactions before reaching the innermost stable circular orbit, the gravitational wave signal emitted by the system is expected to exhibit a cutoff frequency which is a distinctive feature of the waveform. We evaluate this frequency for several equations of state, describing the matter inside the neutron star, and combinations of the binary parameters. We show that, if this frequency will be found in a detected gravitational wave, it will provide valuable information on the behavior of matter in the stellar core.

scholarly journals Constraining the Neutron Star Radius with Joint Gravitational-wave and Short Gamma-Ray Burst Observations of Neutron Star–Black Hole Coalescing Binaries

2019 ◽  
Vol 877 (2) ◽  
pp. 94 ◽  
Author(s):  
Stefano Ascenzi ◽  
Nicola De Lillo ◽  
Carl-Johan Haster ◽  
Frank Ohme ◽  
Francesco Pannarale
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Gamma Ray Burst ◽  
Neutron Star Radius

scholarly journals Protomagnetar research through an analysis of the X-ray plateau in the multi-messengar era

2020 ◽  
Vol 641 ◽  
pp. A56
Author(s):  
Xiaoxiao Ren ◽  
Daming Wei ◽  
Zhenyu Zhu ◽  
Yan Yan ◽  
Chengming Li
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Equations Of State ◽  
Electromagnetic Emission ◽  
Gamma Ray Bursts ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Binary Neutron Star

The joint detection of the gravitational wave signal and the electromagnetic emission from a binary neutron star merger can place unprecedented constraint on the equation of state of supranuclear matter. Although a variety of electromagnetic counterparts have been observed for GW170817, including a short gamma-ray burst, kilonova, and the afterglow emission, the nature of the merger remnant is still unclear, however. The X-ray plateau is another important characteristics of short gamma-ray bursts. This plateau is probably due to the energy injection from a rapidly rotating magnetar. We investigate what we can learn from the detection of a gravitational wave along with the X-ray plateau. In principle, we can estimate the mass of the merger remnant if the X-ray plateau is caused by the central magnetar. We selected eight equations of state that all satisfy the constraint given by the gravitational wave observation, and then calculated the mass of the merger remnants of four short gamma-ray bursts with a well-measured X-ray plateau. If, on the other hand, the mass of the merger remnant can be obtained by gravitational wave information, then by comparing the masses derived by these two different methods can further constrain the equation of state. We discuss the possibility that the merger product is a quark star. In addition, we estimate the possible mass range for the recently discovered X-ray transient CDF-S XT2 that probably originated from a binary neutron star merger. Finally, under the assumption that the post-merger remnant of GW170817 was a supramassive neutron star, we estimated the allowed parameter space of the supramassive neutron star and find that in this case, the magnetic dipole radiation energy is so high that it may have some effects on the short gamma-ray burst and kilonova emission. The lack of detection of these effects suggests that the merger product of GW170817 may not be a supermassive neutron star.

scholarly journals Black-hole–Neutron-star Mergers Are Unlikely Multimessenger Sources

2021 ◽  
Vol 923 (1) ◽  
pp. L2
Author(s):  
Giacomo Fragione
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Equation Of State ◽  
Gravitational Wave ◽  
Internal Structure ◽  
Binary Stars ◽  
Statistical Study ◽  
Gamma Ray ◽  
High Rate ◽  
Upper Limit

Abstract The promise by the LIGO/Virgo/Kagra (LVK) collaboration to detect black-hole–neutron-star (BH–NS) mergers via gravitational wave (GW) emission has recently been fulfilled with the detection of GW200105 and GW200115. Mergers of BH–NS binaries are particularly exciting for their multimessenger potential since GW detection can be followed by an electromagnetic (EM) counterpart (kilonova, gamma-ray burst, afterglow) that can reveal important information on the equation of state (EOS) of NSs and the nature of the BH spin. This can happen whenever the NS does not directly plunge into the BH, but rather is tidally disrupted, leaving behind debris to accrete. We carry out a statistical study of the binary stars that evolve to form a BH–NS binary and compute the rate of merger events that can be followed by an EM counterpart. We find that ≳50% of the mergers can lead to an EM counterpart only in the case where BHs are born highly spinning (χ BH ≳ 0.7), while this fraction does not exceed about 30% for stiff NS EOSs and a few percent for soft NS EOSs for low-spinning BHs (χ BH ≲ 0.2), suggesting that a high rate of EM counterparts of BH–NS would provide support for high natal BH spins. However, the possibilities that BHs are born with near-maximal spins and that NS internal structure is described by a stiff EOS are disfavored by current LVK constraints. Considering that these values only represent an upper limit to observe an EM counterpart due to current observational limitations, such as brightness sensitivity and sky localization, BH–NS mergers are unlikely multimessenger sources.

scholarly journals Multiwaveband quasi-periodic oscillation in the blazar 3C 454.3

2020 ◽  
Vol 501 (1) ◽  
pp. 50-61
Author(s):  
Arkadipta Sarkar ◽  
Alok C Gupta ◽  
Varsha R Chitnis ◽  
Paul J Wiita
Keyword(s):  
Black Hole ◽  
Light Curve ◽  
Gamma Ray ◽  
Moving Average ◽  
Periodic Oscillation ◽  
Physical Models ◽  
Quasi Periodic Oscillation ◽  
Stable Circular Orbit ◽  
Optical Light Curve ◽  
Innermost Stable Circular Orbit

ABSTRACT We report the detection (>4σ) of a quasi-periodic oscillation (QPO) in the gamma-ray light curve of 3C 454.3 along with a simultaneous marginal QPO detection (>2.4σ) in the optical light curves. Periodic flux modulations were detected in both of these wavebands with a dominant period of ∼47 d. The gamma-ray QPO lasted for over 450 d (from MJD 56800 to 57250), resulting in over nine observed cycles which is among the highest number of periods ever detected in a blazar light curve. The optical light curve was not well sampled for almost half of the gamma-ray QPO span due to the daytime transit of the source, which could explain the lower significance of the optical QPO. Autoregressive Integrated Moving Average (ARIMA) modelling of the light curve revealed a significant, exponentially decaying, trend in the light curve during the QPO, along with the 47 d periodicity. We explore several physical models to explain the origin of this transient quasi-periodic modulation and the overall trend in the observed flux with a month-like period. These scenarios include a binary black hole system, a hotspot orbiting close to the innermost stable circular orbit of the supermassive black hole, and precessing jets. We conclude that the most likely scenario involves a region of enhanced emission moving helically inside a curved jet. The helical motion gives rise to the QPO and the curvature (∼0.05○ pc−1) of the jet is responsible for the observed trend in the light curve.

scholarly journals A full relativistic thin disc - the physics of the plunging region and the value of the stress at the ISCO

2021 ◽  
Author(s):  
William J Potter
Keyword(s):  
Black Hole ◽  
Surface Temperature ◽  
Accretion Rate ◽  
Speed Of Light ◽  
Thin Disc ◽  
Stable Circular Orbit ◽  
Stress Surface ◽  
Innermost Stable Circular Orbit ◽  
Turbulent Heating ◽  
Local Surface Temperature

Abstract The widely used Novikov-Thorne relativistic thin disc equations are only valid down to the radius of the innermost-stable circular orbit (ISCO). This leads to an undetermined boundary condition at the ISCO, known as the inner stress of the disc, which sets the luminosity of the disc at the ISCO and introduces considerable ambiguity in accurately determining the mass, spin and accretion rate of black holes from observed spectra. We resolve this ambiguity by self-consistently extending the relativistic disc solution through the ISCO to the black hole horizon by calculating the inspiral of an average disc particle subject to turbulent disc forces, using a new particle-in-disc technique. Traditionally it has been assumed that the stress at the ISCO is zero, with material plunging approximately radially into the black hole at close to the speed of light. We demonstrate that in fact the inspiral is less severe, with several (∼4 − 17) orbits completed before the horizon. This leads to a small non-zero stress and luminosity at and inside the ISCO, with a local surface temperature at the ISCO between ∼0.15 − 0.3 times the maximum surface temperature of the disc, in the case where no dynamically important net magnetic field is present. For a range of disc parameters we calculate the value of the inner stress/surface temperature, which is required when fitting relativistic thin disc models to observations. We resolve a problem in relativistic slim disc models in which turbulent heating becomes inaccurate and falls to zero inside the plunging region.

scholarly journals Lyapunov exponent, ISCO and Kolmogorov–Senai entropy for Kerr–Kiselev black hole

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Monimala Mondal ◽  
Farook Rahaman ◽  
Ksh. Newton Singh
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Lyapunov Exponent ◽  
Circular Orbit ◽  
Real Root ◽  
Angular Frequency ◽  
Geodesic Motion ◽  
Radial Equation ◽  
Stable Circular Orbit ◽  
Innermost Stable Circular Orbit

AbstractGeodesic motion has significant characteristics of space-time. We calculate the principle Lyapunov exponent (LE), which is the inverse of the instability timescale associated with this geodesics and Kolmogorov–Senai (KS) entropy for our rotating Kerr–Kiselev (KK) black hole. We have investigate the existence of stable/unstable equatorial circular orbits via LE and KS entropy for time-like and null circular geodesics. We have shown that both LE and KS entropy can be written in terms of the radial equation of innermost stable circular orbit (ISCO) for time-like circular orbit. Also, we computed the equation marginally bound circular orbit, which gives the radius (smallest real root) of marginally bound circular orbit (MBCO). We found that the null circular geodesics has larger angular frequency than time-like circular geodesics ($$Q_o > Q_{\sigma }$$ Q o > Q σ ). Thus, null-circular geodesics provides the fastest way to circulate KK black holes. Further, it is also to be noted that null circular geodesics has shortest orbital period $$(T_{photon}< T_{ISCO})$$ ( T photon < T ISCO ) among the all possible circular geodesics. Even null circular geodesics traverses fastest than any stable time-like circular geodesics other than the ISCO.

scholarly journals Pulsations in short gamma ray bursts from black hole-neutron star mergers

2013 ◽  
Vol 87 (8) ◽  
Author(s):  
Nicholas Stone ◽  
Abraham Loeb ◽  
Edo Berger
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gamma Ray ◽  
Gamma Ray Bursts

Opening the window

2019 ◽  
pp. 1-22
Author(s):  
Nils Andersson
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Binary Event ◽  
Star Binary

This chapter provides a brief survey of gravitational-wave astronomy, including the recent recent breakthrough detection. It sets the stage for the rest of the book via simple back-of-the-envelope estimates for different sets of sources. The chapter also describes the first detection of a black hole merger (GW150914) as well as the first observed neutron star binary event (GW170817) and introduces some of the ideas required to understand these breakthroughs.

scholarly journals Particle motion around generic black holes coupled to non-linear electrodynamics

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Jaroslav Vrba ◽  
Ahmadjon Abdujabbarov ◽  
Arman Tursunov ◽  
Bobomurat Ahmedov ◽  
Zdeněk Stuchlík
Keyword(s):  
Black Hole ◽  
Energy Conditions ◽  
Test Particles ◽  
Stable Circular Orbit ◽  
Spin Parameter ◽  
Non Linear ◽  
Innermost Stable Circular Orbit ◽  
Charge Parameter ◽  
Upper Estimate ◽  
Black Hole Solutions

Abstract We study spherically symmetric magnetically charged generic black hole solutions of general relativity coupled to non-linear electrodynamics (NED). For characteristic values of the generic spacetime parameters we give the position of horizons in dependence on the charge parameter, demonstrating separation of the black hole and no-horizon solutions, and possibility of existence of solutions containing three horizons. We show that null, weak and strong energy conditions are violated when the outer horizon is approaching the center. We study effective potentials for photons and massive test particles and location of circular photon orbits (CPO) and innermost stable circular orbit (ISCO). We show that the unstable photon orbit can become stable, leading to the possibility of photon capture which affects on silhouette of the central object. The position of ISCO approaches the horizon with increasing charge parameter q and the energy at ISCO decreases with increasing charge parameter. We investigate this phenomenon and summarize for a variety of the generic spacetime parameters the upper estimate on the spin parameter of the Kerr black which can be mimicked by the generic charged black hole solutions.

Sign in / Sign up

Export Citation Format

Share Document