Structure and stability of traversable thin-shell wormholes in Palatini f(R) gravity

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Amer Physical Soc
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We study the structure and stability of traversable wormholes built as (spherically symmetric) thin shells in the context of Palatini f(R) gravity. Using a suitable junction formalism for these theories we find that the effective number of degrees of freedom on the shell is reduced to a single one, which fixes the equation of state to be that of massless stress-energy fields, contrary to the general relativistic and metric f(R) cases. Another major difference is that the surface energy density threading the thin shell, needed in order to sustain the wormhole, can take any sign and may even vanish, depending on the desired features of the corresponding solutions. We illustrate our results by constructing thin-shell wormholes by surgically grafting Schwarzschild space-times and show that these configurations are always linearly unstable. However, surgically joined Reissner-Nordstrom space-times allow for linearly stable, traversable thin-shell wormholes supported by a positive energy density provided that the (squared) mass-to-charge ratio, given by y = Q(2)/M-2, satisfies the constraint 1 < y < 9/8 (corresponding to overcharged Reissner-Nordstrom configurations having a photon sphere) and lies in a region bounded by specific curves defined in terms of the (dimensionless) radius of the shell x(0) = R/M.
© 2020 American Physical Society. F. S. N. L. acknowledges support from the Fundacao para a Ciencia e a Tecnologia (FCT) Scientific Employment Stimulus contract with Reference No. CEECIND/04057/2017 and thanks the FCT research Projects No. UID/FIS/04434/2020 and No. CERN/FIS-PAR/0037/2019. G. J. O. is funded by the Ramon y Cajal Contract No. RYC-2013-13019 (Spain). D. R.-G. is funded by the Atraccion de Talento Investigador program of the Comunidad de Madrid (Spain) No. 2018-T1/TIC-10431 and acknowledges further support from the Ministerio de Ciencia, Innovacion y Universidades (Spain) Project No. PID2019-108485GB-I00/AEI/10.13039/501100011033 and the FCT Project No. PTDC/FIS-PAR/31938/2017. This work is supported by the Spanish Project No. FIS2017-84440-C2-1-P (MINECO/FEDER, EU), Project No. H2020-MSCA-RISE-2017 Grant No. FunFiCO-777740, Project No. SEJI/2017/042 (Generalitat Valenciana), the Consolider Program No. CPANPHY-1205388, the Severo Ochoa Grant No. SEV-2014-0398 (Spain), the FCT Project No. PTDC/FIS-OUT/29048/2017, and the Edital 006/2018 PRONEX (FAPESQ-PB/CNPQ, Brazil, Grant No. 0015/2019). This article is based upon work from COST Actions CA15117 and CA18108, supported by COST (European Cooperation in Science and Technology).
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