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Browsing School of Science and Technology (2015-2019) by Subject "black holes"

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Browsing School of Science and Technology (2015-2019) by Subject "black holes"

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  • All black holes in Lemaˆıtre-Tolman-Bondi inhomogeneous dust collapse 
    Joshi, Pankaj S.; Malafarina, D. (2015-09-08)
    Within the Lemaˆıtre-Tolman-Bondi formalism for gravitational collapse of inhomogeneous dust we analyze the parameter space that leads to the formation of a globally covered singularity (i.e. a black hole) when some ...
  • Are Black Holes Springy? 
    Good, Michael R.R.; Ong, Yen Chin (2014)
    A (3+1)-dimensional asymptotically at Kerr black hole angular speed + can be used to de ne an e ective spring constant, k = m2 +. Its maximum value is the Schwarzschild surface gravity, k = , which rapidly weakens as ...
  • Black Hole Bounces on the Road to Quantum Gravity 
    Malafarina, Daniele (MDPI, 2018-08-28)
    Quantum resolutions of the space-time singularity at the end of gravitational collapse may provide hints towards the properties of a final theory of Quantum-Gravity. The mechanism by which the singularity is avoided and ...
  • Black Hole - Moving Mirror I: An Exact Correspondence 
    Anderson, Paul R.; Good, Michael R.R.; Evans, Charles R. (2015)
    An exact correspondence is shown between a new moving mirror trajectory in (1+1)D and a spacetime in (1+1)D in which a black hole forms from the collapse of a null shell. It is shown that the Bogolubov coe cients between ...
  • Black Hole - Moving Mirror II: Particle Creation 
    Good, Michael R.R.; Anderson, Paul R.; Evans, Charles R. (2016)
    There is an exact correspondence between the simplest solution to Einstein's equa- tions describing the formation of a black hole and a particular moving mirror tra- jectory. In both cases the Bogolubov coe cients in 1+1 ...
  • Black supernovae and black holes in non-local gravity 
    Bambi, Cosimo; Malafarina, Daniele; Modesto, Leonardo (ArXiv, 2016-04-22)
    In a previous paper, we studied the interior solution of a collapsing body in a non-local theory of gravity super-renormalizable at the quantum level. We found that the classical singularity is replaced by a bounce, after ...
  • Classical Collapse to Black Holes and Quantum Bounces: A Review 
    Malafarina, Daniele (Universe, 2017-05-26)
    In the last four decades, different programs have been carried out aiming at understanding the final fate of gravitational collapse of massive bodies once some prescriptions for the behaviour of gravity in the strong field ...
  • Compact objects from gravitational collapse: an analytical toy model 
    Malafarina, D.; Joshi, Pankaj S. (2015)
    We develop here a procedure to obtain regular static configurations as resulting from dynamical gravitational collapse of a massive matter cloud in general relativity. Under certain general physical assumptions for the ...
  • Equilibrium configurations from gravitational collapse 
    Joshi, Pankaj S.; Narayan, Ramesh; Malafarina, D. (2011-11-18)
    We develop here a new procedure within Einstein’s theory of gravity to generate equilibrium configurations that result as the final state of gravitational collapse from regular initial conditions. As a simplification, we ...
  • Genericity aspects in gravitational collapse to black holes and naked singularities 
    Joshi, Pankaj S.; Malafarina, D.; Saraykar, Ravindra V. (2012-07-04)
    We investigate here the genericity and stability aspects for naked singularities and black holes that arise as the final states for a complete gravitational collapse of a spherical massive matter cloud. The form of the ...
  • Gravitational Collapse of Inhomogenous Perfect Fluid 
    Satin, Seema; Malafarina, D.; Joshi, Pankaj S. (2014)
    We study the complete gravitational collapse of a class of inhomogeneous perfect fluid models obtained by introducing small radial perturbations in an otherwise homogeneous matter cloud. The key feature that we assume for ...
  • Gravitational collapse with tangential pressure 
    Malafarina, D.; Joshi, Pankaj S. (2011-05-06)
    Using the general formalism for spherical gravitational collapse developed in [1], we investigate here the final fate of a spherical distribution of a matter cloud, where radial pressures vanish but tangential pressures ...
  • Instability of black hole formation under small pressure perturbations 
    Joshi, Pankaj S.; Malafarina, D. (2012-11-14)
    We investigate here the spectrum of gravitational collapse endstates when arbitrarily small perfect fluid pressures are introduced in the classic black hole formation scenario as described by Oppenheimer, Snyder and Datt ...
  • Note on the effect of a massive accretion disk in the measurements of black hole spins 
    Bambi, Cosimo; Malafarina, D.; Tsukamoto, Naoki (2014-06-25)
    The spin measurement of black holes has important implications in physics and astrophysics. Regardless of the specific technique to estimate the black hole spin, all the current approaches assume that the space-time geometry ...
  • RADIATION FROM AN INERTIAL MIRROR HORIZON 
    Good, Michael; Abdikamalov, Ernazar (Universe, 2020-08)
    The purpose of this study is to investigate radiation from asymptotic zero acceleration motion where a horizon is formed and subsequently detected by an outside witness. A perfectly reflecting moving mirror is used to model ...
  • Recent developments in gravitational collapse and spacetime singularities 
    Joshi, Pankaj S.; Malafarina, D. (2012-01-19)
    It is now known that when a massive star collapses under the force of its own gravity, the final fate of such a continual gravitational collapse will be either a black hole or a naked singularity under a wide variety of ...
  • Scalar field collapse and cosmic censorship 
    Goswami, Rituparno; Joshi, Pankaj S.; Malafarina, D. (2012-02-28)
    We analyze here the final fate of complete gravitational collapse of a massless scalar field within general relativity. A class of dynamical solutions with initial data close to the Friedmann-Lemaˆıtre-Robertson-Walker ...
  • Signatures of Energy Flux in Particle Production: A Black Hole Birth Cry and Death Gasp 
    Good, Michael R.R.; Ong, Yen Chin (2015)
    It is recently argued that if the Hawking radiation process is unitary, then a black hole's mass cannot be monotonically decreasing. We examine the time dependent particle count and negative energy flux in the non-trivial ...
  • Singularity avoidance in quantum-inspired inhomogeneous dust collapse 
    Liu, Yue; Malafarina, D.; Modesto, Leonardo; Bambi, Cosimo (2014-08-17)
    In a previous paper, some of us studied general relativistic homogeneous gravitational collapses for dust and radiation, in which the density profile was replaced by an effective density justified by some quantum gravity ...
  • The instability of black hole formation in gravitational collapse 
    Joshi, Pankaj S.; Malafarina, D. (2011-01-11)
    We consider here the classic scenario given by Oppenheimer, Snyder, and Datt, for the gravitational collapse of a massive matter cloud, and examine its stability under the introduction of small tangential stresses. We show, ...