Results 41 to 50 of about 7,077 (267)
European Physical Journal C: Particles and Fields, 2019 We study scalar perturbations and quasi-normal modes of a nonlinear magnetic-charged black hole surrounded by quintessence. The time evolution of scalar perturbations is studied for different parameters associated with the black hole solution.
Hrishikesh Chakrabarty +2 more
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Stabilizing homogeneous black strings in AdS
Journal of High Energy Physics, 2020 It is known that homogenous black strings in flat spacetime are unstable under long wavelength perturbations. Recently, by including scalar fields that depend on the extended coordinates only, homogenous black strings have been constructed in the ...
Adolfo Cisterna +2 more
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Massive cosmological scalar perturbations [PDF]
Physical Review D, 2012 We study the cosmological perturbations of the new bi-metric gravity proposed by Hassan and Rosen \cite{hasan} as a representation of massive gravity. The mass term in the model, in addition of ensuring ghost freedom for both metrics, causes the two scale factors to mix at the cosmological level and this affects the cosmological perturbation of the ...
Khosravi, Nima +2 more
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Nonlinear perturbations in scalar-tensor cosmologies
Physical Review D, 2004 References added; typos corrected; accepted for publication on Phys.
Perrotta, F. +3 more
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European Physical Journal C: Particles and Fields, 2018 We study the stability under scalar perturbations, and we compute the quasinormal modes of the Einstein–Born–Infeld dilaton spacetime in $$1+3$$ 1+3 dimensions.
Kyriakos Destounis +2 more
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Cosmological perturbations in the spatially covariant gravity with a dynamical lapse function
Physics Letters B, 2022 We investigate the scalar perturbations in a class of spatially covariant gravity theory with a dynamical lapse function. Generally, there are two scalar degrees of freedom due to the presence of the velocity of the lapse function.
Xue-Zheng Zhu, Yang Yu, Xian Gao
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Scalar perturbations in deflationary cosmological models
, 1998 We consider scalar perturbations of energy--density for a class of cosmological models where an early phase of accelerated expansion evolves, without any fine--tuning for graceful exit, towards the standard Friedman eras of observed universe. The geometric procedure which generates such models agrees with results for string cosmology since it works if ...
CAPOZZIELLO S +2 more
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A general solution for scalar perturbations in bouncing cosmologies [PDF]
Journal of Cosmology and Astroparticle Physics, 2006 Bouncing cosmologies, suggested by String/M-theory, may provide an alternative to standard inflation to account for the origin of inhomogeneities in our universe. The fundamental question regards the correct way to evolve the scalar perturbations through the bounce. In this work, we determine the evolution of perturbations and the final spectrum for an
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COSMOLOGICAL PERTURBATIONS IN PRESENCE OF SCALAR FIELDS
Odessa Astronomical Publications, 2014 We investigate the role of the scalar field assuming its presence at late stages of the Universe evolution together with dust presented by a system of an arbitrary number of gravitating masses (galaxies, groups of galaxies and clusters of galaxies) and ...
A. Yu. Burgazli, M. Eingorn, A. Zhuk
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The Open Journal of Astrophysics, 2021 We apply the squeezed state formalism to scalar field dark matter (e.g. axion) perturbations generated during inflation. As for the inflationary perturbations, the scalar field state becomes highly squeezed as modes exit the horizon. For as long as $H>m_\
Jondalar L. J. Kuß, David J. E. Marsh
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