General Relativity and Quantum Cosmology, abstract
gr-qc/0501105

From: Remo Garattini [view email]

Date: Mon, 31 Jan 2005 15:31:23 GMT (13kb)

Self Sustained Traversable Wormholes?

Authors: Remo Garattini

Comments: RevTeX 4, 12 pages. Accepted for publication on Classical and Quantum Gravity

Journal-ref: Class.Quant.Grav. 22 (2005) 1105-1118

We compute the graviton one loop contribution to a classical energy in a traversable wormhole background. Such a contribution is evaluated by means of a variational approach with Gaussian trial wave functionals. A zeta function regularization is involved to handle with divergences. A renormalization procedure is introduced and the finite one loop energy is considered as a self-consistent source for the traversable wormhole.

http://arxiv.org/abs/gr-qc/0501105

General Relativity and Quantum Cosmology, abstract
gr-qc/0701019

From: Remo Garattini [view email]

Date: Tue, 2 Jan 2007 15:30:47 GMT (42kb)

Self sustained traversable wormholes and the equation of state

Authors: Remo Garattini

Comments: Uses RevTeX 4. 21 pages. Submitted to Classical and Quantum Gravity. Extended version of the talk given at ERE2006 (Palma de Mallorca, September 4-8, 2006) and of the talk given at MG11-GT5, Berlin, 23-29 July, 2006

We compute the graviton one loop contribution to a classical energy in a \textit{traversable} wormhole background. The form of the shape function considered is obtained by the equation of state $p=\omega\rho$. We investigate the size of the wormhole as a function of the parameter $\omega$. The investigation is evaluated by means of a variational approach with Gaussian trial wave functionals. A zeta function regularization is involved to handle with divergences. A renormalization procedure is introduced and the finite one loop energy is considered as a \textit{self-consistent} source for the traversable wormhole.The case of the phantom region is briefly discussed.

http://arxiv.org/abs/gr-qc/0701019

General Relativity and Quantum Cosmology, abstract
gr-qc/0701020

From: Remo Garattini [view email]

Date: Tue, 2 Jan 2007 16:57:51 GMT (59kb)

Self sustained phantom wormholes in semi-classical gravity

Authors: Remo Garattini, Francisco S. N. Lobo

Comments: Uses RevTeX 4. 10 pages

A possible candidate for the late time accelerated expanding Universe is phantom energy, which possesses rather bizarre properties, such as the prediction of a Big Rip singularity and the violation of the null energy condition. The latter is a fundamental ingredient of traversable wormholes, and it has been shown that phantom energy may indeed sustain these exotic geometries. Inspired by the evolving dark energy parameter crossing the phantom divide, we consider in this work a varying equation of state parameter dependent on the radial coordinate, i.e., $\omega(r)=p(r)/\rho(r)$. We shall impose that phantom energy is concentrated in the neighborhood of the throat, to ensure the flaring out condition, and several models are analyzed. We shall also consider the possibility that these phantom wormholes be sustained by their own quantum fluctuations. The energy density of the graviton one loop contribution to a classical energy in a phantom wormhole background and the finite one loop energy density are considered as a self-consistent source for these wormhole geometries. The latter semi-classical approach prohibits solutions with a constant equation of state parameter, which further motivates the imposition of a radial dependent parameter, $\omega(r)$, and only permits solutions with a steep positive slope proportional to the radial derivative of the equation of state parameter, evaluated at the throat. The size of the wormhole throat as a function of the relevant parameters is also explored.

http://arxiv.org/abs/gr-qc/0701020