scholarly journals Gravitational wave signatures of the absence of an event horizon: Nonradial oscillations of a thin-shell gravastar

2009 ◽  
Vol 80 (12) ◽  
Author(s):  
Paolo Pani ◽  
Emanuele Berti ◽  
Vitor Cardoso ◽  
Yanbei Chen ◽  
Richard Norte
Keyword(s):  
Gravitational Wave ◽  
Event Horizon ◽  
Thin Shell ◽  
Nonradial Oscillations

scholarly journals Isotropic Gravastar Model in Rastall Gravity

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
G. Abbas ◽  
K. Majeed
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Analytical Solutions ◽  
Thin Shell ◽  
Graphical Analysis ◽  
Stiff Fluid ◽  
Matter Distribution ◽  
The Third ◽  
Schwarzschild Geometry ◽  
Third Phase

In the present paper, we have introduced a new model of gravastar with an isotropic matter distribution in Rastall gravity by the Mazur–Mottola (2004) mechanism. Mazur–Mottola approach is about the construction of gravastar which is predicted as an alternative to black hole. By following this convention, we define gravastar in the form of three phases. The first one is an interior phase which has negative density; the second part consists of thin shell comprising ultrarelativistic stiff fluid for which we have discussed the length, energy, and entropy. By the graphical analysis of entropy, we have shown that our proposed thin shell gravastar model is potentially stable. The third phase of gravastar is defined by the exterior Schwarzschild geometry. For the interior of gravastar, we have found the analytical solutions free from any singularity and the event horizon in the framework of Rastall gravity.

scholarly journals The gravitational wave 'probability event horizon' for double neutron star mergers

2005 ◽  
Vol 364 (3) ◽  
pp. 807-812 ◽  
Author(s):  
D. M. Coward ◽  
M. Lilley ◽  
E. J. Howell ◽  
R. R. Burman ◽  
D. G. Blair
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Event Horizon

scholarly journals Gravitational-wave signature of a thin-shell gravastar

2010 ◽  
Vol 222 ◽  
pp. 012032 ◽  
Author(s):  
Paolo Pani ◽  
Emanuele Berti ◽  
Vitor Cardoso ◽  
Yanbei Chen ◽  
Richard Norte
Keyword(s):  
Gravitational Wave ◽  
Thin Shell ◽  
Wave Signature

scholarly journals Is the Gravitational-Wave Ringdown a Probe of the Event Horizon?

2016 ◽  
Vol 116 (17) ◽  
Author(s):  
Vitor Cardoso ◽  
Edgardo Franzin ◽  
Paolo Pani
Keyword(s):  
Gravitational Wave ◽  
Event Horizon

scholarly journals Qualifying ringdown and shadow of black holes under general parametrized metrics with photon orbits

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Song Li ◽  
Ahmadjon A. Abdujabbarov ◽  
Wen-Biao Han
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Lyapunov Exponent ◽  
Gravitational Wave ◽  
Decay Rate ◽  
Event Horizon ◽  
Equatorial Plane ◽  
Circular Orbits ◽  
The Future

AbstractThe motion of photons around black holes determines the shape of shadow and match the ringdown properties of a perturbed black hole. Observations of shadows and ringdown waveforms will reveal the nature of black holes. In this paper, we study the motion of photons in a general parametrized metric beyond the Kerr hypothesis. We investigated the radius and frequency of the photon circular orbits on the equatorial plane and obtained fitted formula with varied parameters. The Lyapunov exponent which connects to the decay rate of the ringdown amplitude is also calculated. We also analyzed the shape of shadow with full parameters of the generally axisymmetric metric. Our results imply the potential constraint on black hole parameters by combining the Event Horizon Telescope and gravitational wave observations in the future.

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