scholarly journals Extreme-mass-ratio inspiral corrections to the angular velocity and redshift factor of a mass in circular orbit about a Kerr black hole

2012 ◽  
Vol 86 (8) ◽  
Author(s):  
Abhay G. Shah ◽  
John L. Friedman ◽  
Tobias S. Keidl
Keyword(s):  
Black Hole ◽  
Angular Velocity ◽  
Circular Orbit ◽  
Kerr Black Hole ◽  
Mass Ratio

scholarly journals Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA*

2018 ◽  
Vol 618 ◽  
pp. L10 ◽  
Author(s):  
◽  
R. Abuter ◽  
A. Amorim ◽  
M. Bauböck ◽  
J. P. Berger ◽  
...  
Keyword(s):  
Black Hole ◽  
Circular Orbit ◽  
Near Infrared ◽  
Hot Spot ◽  
Kerr Black Hole ◽  
Polarization Angle ◽  
Gravitational Radius ◽  
Massive Black Hole ◽  
Poloidal Magnetic Field ◽  
Continuous Rotation

We report the detection of continuous positional and polarization changes of the compact source SgrA* in high states (“flares”) of its variable near-infrared emission with the near-infrared GRAVITY-Very Large Telescope Interferometer (VLTI) beam-combining instrument. In three prominent bright flares, the position centroids exhibit clockwise looped motion on the sky, on scales of typically 150 μas over a few tens of minutes, corresponding to about 30% the speed of light. At the same time, the flares exhibit continuous rotation of the polarization angle, with about the same 45(±15) min period as that of the centroid motions. Modelling with relativistic ray tracing shows that these findings are all consistent with a near face-on, circular orbit of a compact polarized “hot spot” of infrared synchrotron emission at approximately six to ten times the gravitational radius of a black hole of 4 million solar masses. This corresponds to the region just outside the innermost, stable, prograde circular orbit (ISCO) of a Schwarzschild–Kerr black hole, or near the retrograde ISCO of a highly spun-up Kerr hole. The polarization signature is consistent with orbital motion in a strong poloidal magnetic field.

scholarly journals Testing Gravity Theory With Extreme Mass-Ratio Inspirals: Recent Progress

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 11
Author(s):  
Shucheng Yang ◽  
Shuo Xin ◽  
Chen Zhang ◽  
Wenbiao Han
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Recent Progress ◽  
Central Body ◽  
Low Frequency ◽  
Kerr Black Hole ◽  
Compact Object ◽  
Wave Dispersion ◽  
Gravity Theory ◽  
Mass Ratio

A compact object captured by a supermassive black hole, named as extreme-mass-ratio inspiral (EMRI), is one of the most important gravitational wave sources for low-frequency interferometers such as LISA, Taiji, and TianQin. EMRIs can be used to accurately map the space-time of the central massive body. In the present paper, we introduce our recent progress on testing gravity theory with EMRIs. We demonstrate how to constrain gravitational wave dispersion and measure the deviation of the central body from the Kerr black hole. By using binary-EMRIs, the gravitational recoil and mass loss due to merger will be measured in a higher accuracy compared with the current LIGO observations. All these potential constrains and measurements will be useful for test of the gravity theory.

scholarly journals Motion deviation of test body induced by spin and cosmological constant in extreme mass ratio inspiral binary system

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Yu-Peng Zhang ◽  
Shao-Wen Wei ◽  
Pau Amaro-Seoane ◽  
Jie Yang ◽  
Yu-Xiao Liu
Keyword(s):  
Black Hole ◽  
Phase Shift ◽  
Cosmological Constant ◽  
Gravitational Waves ◽  
Test Particle ◽  
Circular Orbit ◽  
Mass Ratio ◽  
Stable Circular Orbit ◽  
Innermost Stable Circular Orbit ◽  
The Impact

Abstract The future space-borne detectors will provide the possibility to detect gravitational waves emitted from extreme mass ratio inspirals of stellar-mass compact objects into supermassive black holes. It is natural to expect that the spin of the compact object and cosmological constant will affect the orbit of the inspiral process and hence lead to the considerable phase shift of the corresponding gravitational waves. In this paper, we investigate the motion of a spinning test particle in the spinning black hole background with a cosmological constant and give the order of motion deviation induced by the particle’s spin and the cosmological constant by considering the corresponding innermost stable circular orbit. By taking the neutron star or kerr black hole as the small body, the deviations of the innermost stable circular orbit parameters induced by the particle’s spin and cosmological constant are given. Our results show that the deviation induced by particle’s spin is much larger than that induced by cosmological constant when the test particle locates not very far away from the black hole, the accumulation of phase shift during the inspiral from the cosmological constant can be ignored when compared to the one induced by the particle’s spin. However when the test particle locates very far away from the black hole, the impact from the cosmological constant will increase dramatically. Therefore the accumulation of phase shift for the whole process of inspiral induced by the cosmological constant and the particle’s spin should be handled with caution.

Black Hole Spin

2014 ◽  
Author(s):  
Charles D. Bailyn
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Accretion Disk ◽  
Circular Orbit ◽  
Kerr Black Hole ◽  
Schwarzschild Black Hole ◽  
Physical Size ◽  
Stable Circular Orbit ◽  
Innermost Stable Circular Orbit

This chapter examines the spin of a black hole. The spin is usually described as a nondimensional parameter, which can range from zero (a nonspinning black hole) to one (a situation described as “maximally spinning”). The differences in space-time between a nonspinning Schwarzschild black hole and a Kerr black hole of the same mass have potentially observable effects. The most obvious of these differences is the position of the innermost stable circular orbit (ISCO), which has a significant effect on the inner edge of an accretion disk. It is through determination of the physical size of the ISCO that the spins of black holes are determined.

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