Amir Hadi Ziaie, Arash Ranjbar, Hamid Reza Sepangi
Motivated by the geometrical interpretation of Brans-Dicke scalar field which may also act as a torsion potential in Lyra geometry, we study the effects of space-time torsion on the dynamics of a collapsing massive star. Taking the matter content as spherically symmetric, homogeneous perfect fluid with the equation of state $p=w\rho$, we show that as long as regularity of the initial data and weak energy condition are satisfied, the space-time torsion may delay the formation of an apparent horizon. It is found that the rate of temporal change of the torsion scalar potential plays the role of a frictional term which makes the collapse to proceed at a slower rate. As a result, a class of collapse models are found for which the apparent horizon fails to appear until the singularity is formed.
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http://arxiv.org/abs/1306.2601
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