We investigate the role played by density inhomogeneities and dissipation on the final outcome of collapse of a self-gravitating sphere. By imposing a perturbative scheme on the thermodynamical variables and gravitational potentials we track the evolution of the collapse process starting off with an initially static perfect fluid sphere which is shear-free. The collapsing core dissipates energy in the form of a radial heat flux with the exterior spacetime being filled with a superposition of null energy and an anisotropic string distribution. The ensuing dynamical process slowly evolves into a shear-like regime with contributions from the heat flux and density fluctuations. We show that the anisotropy due to the presence of the strings drives the stellar fluid towards instability with this effect being enhanced by the density inhomogeneity. An interesting and novel consequence of this collapse is the earlier formation of the horizon.

中文翻译：

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耗散坍塌过程中的稳定性和地平线形成

我们研究了密度不均匀性和耗散对自引力球体坍塌的最终结果所起的作用。通过对热力学变量和引力势施加扰动方案，我们跟踪坍塌过程的演变，从初始静态的完美流体球开始，该球体是无剪切的。坍缩的核心以径向热通量的形式耗散能量，外部时空充满零能量和各向异性弦分布的叠加。随后的动力学过程慢慢演变成类似剪切的状态，热通量和密度波动的贡献。我们表明，由于弦的存在导致的各向异性驱使恒星流体趋于不稳定，而密度不均匀性增强了这种效应。