The Experts below are selected from a list of 33567 Experts worldwide ranked by ideXlab platform
David Garfinkle - One of the best experts on this subject based on the ideXlab platform.
-
on field theory thermalization from Gravitational Collapse
Journal of High Energy Physics, 2012Co-Authors: David Garfinkle, Leopoldo Pando A Zayas, Dori ReichmannAbstract:Motivated by its field theory interpretation, we study Gravitational Collapse of a minimally coupled massless scalar field in Einstein gravity with a negative cosmological constant. After demonstrating the accuracy of the numerical algorithm for the questions we are interested in, we investigate various aspects of the apparent horizon formation. In particular, we study the time and radius of the apparent horizon formed as functions of the initial Gaussian profile for the scalar field. We comment on several aspects of the dual field theory picture.
-
rapid thermalization in field theory from Gravitational Collapse
Physical Review D, 2011Co-Authors: David Garfinkle, Leopoldo Pando A ZayasAbstract:Motivated by the duality with thermalization in field theory, we study Gravitational Collapse of a minimally coupled massless scalar field in Einstein gravity with a negative cosmological constant. We investigate the system numerically and establish that for small values of the initial amplitude of the scalar field there is no black hole formation, rather, the scalar field performs an oscillatory motion typical of geodesics in AdS. For large enough values of the amplitude of the scalar field we find black hole formation which we detect numerically as the emergence of an apparent horizon. Using the time of formation as an estimate for thermalization in the field theory we conclude that thermalization occurs very rapidly, close to the causal bound for a very wide range of black hole masses. We further study the thermalization time in more detail as a function of the amplitude and the width of the initial Gaussian scalar field profile and detect a rather mild structure.
-
examining Gravitational Collapse with test scalar fields
Classical and Quantum Gravity, 2010Co-Authors: Ryo Saotome, Ratindranath Akhoury, David GarfinkleAbstract:Numerical simulations are performed of a test scalar field in a spacetime undergoing Gravitational Collapse. The behavior of the scalar field near the singularity is examined and implications for generic singularities are discussed. In particular, our example is the first confirmation of the Belinskii, Khalatnikov and Lifschitz (BKL) conjecture for an asymptotically flat spacetime.
-
examining Gravitational Collapse with test scalar fields
arXiv: General Relativity and Quantum Cosmology, 2010Co-Authors: Ryo Saotome, Ratindranath Akhoury, David GarfinkleAbstract:Numerical simulations are performed of a test scalar field in a spacetime undergoing Gravitational Collapse. The behavior of the scalar field near the singularity is examined and implications for generic singularities are discussed. In particular, our example is the first confirmation of the BKL conjecture for an asymptotically flat spacetime.
-
numerical simulations of Gravitational Collapse in einstein aether theory
Physical Review D, 2007Co-Authors: David Garfinkle, Christopher Eling, Ted JacobsonAbstract:We study Gravitational Collapse of a spherically symmetric scalar field in Einstein-aether theory (general relativity coupled to a dynamical unit timelike vector field). The initial value formulation is developed, and numerical simulations are performed. The Collapse produces regular, stationary black holes, as long as the aether coupling constants are not too large. For larger couplings a finite area singularity occurs. These results are shown to be consistent with the stationary solutions found previously.
Xiaobao Wang - One of the best experts on this subject based on the ideXlab platform.
-
critical phenomena in Gravitational Collapse of husain martinez nunez scalar field
arXiv: General Relativity and Quantum Cosmology, 2019Co-Authors: Xiaobao Wang, Sijie GaoAbstract:We construct analytical models to study the critical phenomena in Gravitational Collapse of the Husain-Martinez-Nunez massless scalar field. We first use the cut-and-paste technique to match the conformally flat solution ($c=0$ ) onto an outgoing Vaidya solution. To guarantee the continuity of the metric and the extrinsic curvature, we prove that the two solutions must be joined at a null hypersurface and the metric function in Vaidya spacetime must satisfy some constraints. We find that the mass of the black hole in the resulting spacetime takes the form $M\propto (p-p^*)^\gamma$, where the critical exponent $\gamma$ is equal to $0.5$. For the case $c\neq 0$, we show that the scalar field must be joined onto two pieces of Vaidya spacetimes to avoid a naked singularity. We also derive the power-law mass formula with $\gamma=0.5$. Compared with previous analytical models constructed from a different scalar field with continuous self-similarity, we obtain the same value of $\gamma$. However, we show that the solution with $c\neq 0$ is not self-similar. Therefore, we provide a rare example that a scalar field without self-similarity also possesses the features of critical Collapse.
-
critical phenomena in Gravitational Collapse of husain martinez nunez scalar field
European Physical Journal C, 2019Co-Authors: Xiaobao Wang, Sijie GaoAbstract:We construct analytical models to study the critical phenomena in Gravitational Collapse of the Husain-Martinez-Nunez massless scalar field. We first use the cut-and-paste technique to match the conformally flat solution ($$c=0$$ ) onto an outgoing Vaidya solution. To guarantee the continuity of the metric and the extrinsic curvature, we prove that the two solutions must be joined at a null hypersurface and the metric function in Vaidya spacetime must satisfy certain constraints. We find that the mass of the black hole in the resulting spacetime takes the form $$M\propto (p-p^*)^\gamma $$, where the critical exponent $$\gamma $$ is equal to 0.5. For the case $$c\ne 0$$, we show that the scalar field must be joined onto two pieces of Vaidya spacetimes to avoid a naked singularity. We also derive the power-law mass formula with $$\gamma =0.5$$. Compared with previous analytical models which were constructed from a different scalar field with continuous self-similarity, we obtain the same value of $$\gamma $$. However, we show that the solution with $$c\ne 0$$ is not self-similar. Therefore, we provide a rare example that a scalar field without self-similarity also possesses the features of critical Collapse.
Sijie Gao - One of the best experts on this subject based on the ideXlab platform.
-
critical phenomena in Gravitational Collapse of husain martinez nunez scalar field
arXiv: General Relativity and Quantum Cosmology, 2019Co-Authors: Xiaobao Wang, Sijie GaoAbstract:We construct analytical models to study the critical phenomena in Gravitational Collapse of the Husain-Martinez-Nunez massless scalar field. We first use the cut-and-paste technique to match the conformally flat solution ($c=0$ ) onto an outgoing Vaidya solution. To guarantee the continuity of the metric and the extrinsic curvature, we prove that the two solutions must be joined at a null hypersurface and the metric function in Vaidya spacetime must satisfy some constraints. We find that the mass of the black hole in the resulting spacetime takes the form $M\propto (p-p^*)^\gamma$, where the critical exponent $\gamma$ is equal to $0.5$. For the case $c\neq 0$, we show that the scalar field must be joined onto two pieces of Vaidya spacetimes to avoid a naked singularity. We also derive the power-law mass formula with $\gamma=0.5$. Compared with previous analytical models constructed from a different scalar field with continuous self-similarity, we obtain the same value of $\gamma$. However, we show that the solution with $c\neq 0$ is not self-similar. Therefore, we provide a rare example that a scalar field without self-similarity also possesses the features of critical Collapse.
-
critical phenomena in Gravitational Collapse of husain martinez nunez scalar field
European Physical Journal C, 2019Co-Authors: Xiaobao Wang, Sijie GaoAbstract:We construct analytical models to study the critical phenomena in Gravitational Collapse of the Husain-Martinez-Nunez massless scalar field. We first use the cut-and-paste technique to match the conformally flat solution ($$c=0$$ ) onto an outgoing Vaidya solution. To guarantee the continuity of the metric and the extrinsic curvature, we prove that the two solutions must be joined at a null hypersurface and the metric function in Vaidya spacetime must satisfy certain constraints. We find that the mass of the black hole in the resulting spacetime takes the form $$M\propto (p-p^*)^\gamma $$, where the critical exponent $$\gamma $$ is equal to 0.5. For the case $$c\ne 0$$, we show that the scalar field must be joined onto two pieces of Vaidya spacetimes to avoid a naked singularity. We also derive the power-law mass formula with $$\gamma =0.5$$. Compared with previous analytical models which were constructed from a different scalar field with continuous self-similarity, we obtain the same value of $$\gamma $$. However, we show that the solution with $$c\ne 0$$ is not self-similar. Therefore, we provide a rare example that a scalar field without self-similarity also possesses the features of critical Collapse.
Ashley T Barnes - One of the best experts on this subject based on the ideXlab platform.
-
young massive star cluster formation in the galactic centre is driven by global Gravitational Collapse of high mass molecular clouds
Monthly Notices of the Royal Astronomical Society, 2019Co-Authors: Ashley T Barnes, S N Longmore, A Avison, Y Contreras, Adam Ginsburg, J D Henshaw, J M RathborneAbstract:Young massive clusters (YMCs) are the most compact, high-mass stellar systems still forming at the present day. The precursor clouds to such systems are, however, rare due to their large initial gas mass reservoirs and rapid dispersal timescales due to stellar feedback. Nonetheless, unlike their high-z counterparts, these precursors are resolvable down to the sites of individually forming stars, and hence represent the ideal environments in which to test the current theories of star and cluster formation. Using high angular resolution (1$^{\prime\prime}$ / 0.05pc) and sensitivity ALMA observations of two YMC progenitor clouds in the Galactic Centre, we have identified a suite of molecular line transitions -- e.g. c-C$_{3}$H$_{2} $($7-6$) -- that are believed to be optically thin, and reliably trace the gas structure in the highest density gas on star-forming core scales. We conduct a virial analysis of the identified core and proto-cluster regions, and show that half of the cores (5/10) and both proto-clusters are unstable to Gravitational Collapse. This is the first kinematic evidence of global Gravitational Collapse in YMC precursor clouds at such an early evolutionary stage. The implications are that if these clouds are to form YMCs, then they likely do so via the "conveyor-belt" mode, whereby stars continually form within dispersed dense gas cores as the cloud undergoes global Gravitational Collapse. The concurrent contraction of both the cluster-scale gas and embedded (proto)stars ultimately leads to the high (proto)stellar density in YMCs.
Hideki Maeda - One of the best experts on this subject based on the ideXlab platform.
-
final fate of spherically symmetric Gravitational Collapse of a dust cloud in einstein gauss bonnet gravity
Physical Review D, 2006Co-Authors: Hideki MaedaAbstract:We give a model of the higher-dimensional spherically symmetric Gravitational Collapse of a dust cloud including the perturbative effects of quantum gravity. The n({>=}5)-dimensional action with the Gauss-Bonnet term for gravity is considered and a simple formulation of the basic equations is given for the spacetime M{approx_equal}M{sup 2}xK{sup n-2} with a perfect fluid and a cosmological constant. This is a generalization of the Misner-Sharp formalism of the four-dimensional spherically symmetric spacetime with a perfect fluid in general relativity. The whole picture and the final fate of the Gravitational Collapse of a dust cloud differ greatly between the cases with n=5 and n{>=}6. There are two families of solutions, which we call plus-branch and the minus-branch solutions. A plus-branch solution can be attached to the outside vacuum region which is asymptotically anti-de Sitter in spite of the absence of a cosmological constant. Bounce inevitably occurs in the plus-branch solution for n{>=}6, and consequently singularities cannot be formed. Since there is no trapped surface in the plus-branch solution, the singularity formed in the case of n=5 must be naked. On the other hand, a minus-branch solution can be attached to the outside asymptotically flat vacuum region. We show that naked singularities aremore » massless for n{>=}6, while massive naked singularities are possible for n=5. In the homogeneous Collapse represented by the flat Friedmann-Robertson-Walker solution, the singularity formed is spacelike for n{>=}6, while it is ingoing-null for n=5. In the inhomogeneous Collapse with smooth initial data, the strong cosmic censorship hypothesis holds for n{>=}10 and for n=9 depending on the parameters in the initial data, while a naked singularity is always formed for 5{<=}n{<=}8. These naked singularities can be globally naked when the initial surface radius of the dust cloud is fine-tuned, and then the weak cosmic censorship hypothesis is violated.« less
-
convergence to a self similar solution in general relativistic Gravitational Collapse
Physical Review D, 2001Co-Authors: Tomohiro Harada, Hideki MaedaAbstract:We study the spherical Collapse of a perfect fluid with an equation of state $P=k\rho$ by full general relativistic numerical simulations. For $0
