3 papers
gr-qc2024
Spectrum of Primordial Gravitational Waves in Presence of a Cosmic String
S. Azar Ag Galeh, A. M. Abbassi, M. H. Abbassi
In this paper we consider an inflating universe with long straight cosmic string along z-axis. We show that the effect of cosmic string can be taken as a perturbation on the backgr…
astro-ph.CO2020
Signatures of Spatial Curvature on Growth of Structures
Mohammad H. Abbassi, Amir H. Abbassi
We write down Boltzmann equation for massive particles in a spatially curved FRW universe and solve the approximate line-of-sight solution for evolution of matter density, includin…
gr-qc2018
Anisotropic Mimetic Cosmology
M. H. Abbassi, A. Jozani, H. R. Sepangi
We consider a mimetic set up in which the mimetic scalar is coupled to a vector field. It is shown that such a field with a time-like component does not contribute to the backgroun…