156 citations · 1.1k across the 74 of their papers we have counts for
35 papers · 1 filter
Black Hole Shadows and Quasinormal Modes with Dark Matter at the Horizon
Armin Sadeghi, Javad T. Firouzjaee, Saeed Fakhry
In this work, we study the effect of a surrounding dark matter halo on two horizon-scale observables of a black hole: its shadow and quasinormal-mode spectrum. We consider a Schwar…
Primordial black hole in Lorentz-violating theories: Insights from Bumblebee gravity
Mohsen Khodadi, Javad T. Firouzjaee
The Bumblebee gravity (BG) model, featuring spontaneous Lorentz symmetry breaking via a vector field non-minimally coupled to curvature, has been widely used to explore Lorentz-vio…
Fragility of stealth solutions in mimetic gravity
Alireza Allahyari, Clarisse Donio, Mohammad Ali Gorji +2
We study a broad class of constrained mimetic-type extensions of general relativity with action , where i…
Confronting dark energy in Harada's Conformal Killing Gravity with observational data
Mohsen Khodadi, Gaetano Lambiase, Javad. T. Firouzjaee
Based on a comprehensive analysis of recent observational data-a combination of DESI DR1, Planck CMB, and Pantheon+ SN Ia-this study critically evaluates the two dark energy (DE) p…
Cosmological Inflation in Gravity
Maryam Shiravand, Saeed Fakhry, Javad T. Firouzjaee +1
Cosmological inflation provides the standard description of the early accelerated expansion of the Universe, but the shortcomings of General Relativity (GR) motivate the search for…
Primordial observables of explicit diffeomorphism violation in gravity
Mohsen Khodadi, Nils A. Nilsson, Gaetano Lambiase +1
We investigate the potential for current and future gravitational-wave detectors to observe imprints of explicit diffeomorphism violation in primordial signals. Starting from a sim…
Toward Gravitational Lensing in Modified Theories of Gravity
Ali Tizfahm, Saeed Fakhry, Javad T. Firouzjaee +1
In this study, we investigate gravitational lensing within modified gravity frameworks, focusing on the Hu-Sawicki and normal branch Dvali-Gabadadze-Porrati (nDGP) models, a…
A note on the stability of the Cauchy horizon in regular black holes without mass inflation
Mohsen Khodadi, Javad T. Firouzjaee
Unlike generic models of regular black holes (BHs) with nonzero surface gravity on both Cauchy and event horizons, an inner-degenerate counterpart with zero Cauchy horizon surface…
Event Horizon Telescope observations exclude compact objects in baseline mimetic gravity
Mohsen Khodadi, Sunny Vagnozzi, Javad T. Firouzjaee
Mimetic gravity has gained significant appeal in cosmological contexts, but static spherically symmetric space-times within the baseline theory are highly non-trivial: the two natu…
Cosmological LTB Black Hole in a Quintom Universe
Sareh Eslamzadeh, Kourosh Nozari, J. T. Firouzjaee
We study cosmological Lemaitre-Tolman-Bondi (LTB) black hole thermodynamics immersed in a quintom universe. We investigate some thermodynamic aspects of such a black hole in detail…
A Survey of Strong Cosmic Censorship Conjecture Beyond Einstein's Gravity
Mohsen Khodadi, Javad T. Firouzjaee
The strong cosmic censorship conjecture (SCCC) proposed by Penrose states that the presence of the inner Cauchy horizon () in the black hole solutions does not threat…
Hawking Temperature for 4D-Einstein-Gauss-Bonnet Black Holes from uncertainty principle
Sara Azizi, Sareh Eslamzadeh, Javad T. Firouzjaee +1
Inspired by string theory, Heisenberg's uncertainty principle can be generalized to include the photon-electron gravitational interaction, which leads to the Generalized Uncertaint…
Energy condition and cosmic censorship conjecture in the perfect fluid collapse
Javad T. Firouzjaee
The hypothesis of cosmic censorship plays a crucial role in classical general relativity, namely, to ensure that naked singularities would never occur from the black hole singulari…
Radiation from Einstein-Gauss-Bonnet de Sitter Black Hole via Tunneling Process
Sareh Eslamzadeh, Javad T. Firouzjaee, Kourosh Nozari
In this paper, we probe in 4D Einstein-Gauss-Bonnet black hole and its thermodynamics. We illustrate the three asymptotically 4D EGB spacetime as an asymptotically flat, de Sitter,…
Nonlinear phenomena in general relativity
Alireza Allahyari, Javad T. Firouzjaee, Reza Mansouri
The perturbation theory plays an important role in studying structure formation in cosmology and post-Newtonian physics, but not all phenomena can be described by the linear pertur…
Quantum decoherence from entanglement during inflation
Abasalt Rostami, Javad T. Firouzjaee
We study the primary entanglement effect on the decoherence of fields reduced density matrix which are in interaction with another fields or independent mode functions. We show tha…
Charged cosmological black hole
Rahim Moradi, Clément Stahl, Javad T. Firouzjaee +1
The cosmological black holes are black holes living not in an asymptotically flat universe but in an expanding spacetime. They have a rich dynamics in particular for their mass and…
Foliation dependence of black hole apparent horizons in spherical symmetry
Valerio Faraoni, George F. R. Ellis, Javad T. Firouzjaee +2
Numerical studies of gravitational collapse to black holes make use of apparent horizons, which are intrinsically foliation-dependent. We expose the problem and discuss possible so…
Primordial black holes in linear and non-linear regimes
Alireza Allahyari, Javad T. Firouzjaee, Ali Akbar Abolhasani
Using the concept of apparent horizon for dynamical black holes, we revisit the formation of primordial black holes (PBH) in the early universe for both linear and non-linear regim…
Particle creation rate for dynamical black holes
Javad T. Firouzjaee, George F R Ellis
We present the particle creation probability rate around a general black hole as an outcome of quantum fluctuations. Using the uncertainty principle for these fluctuation, we deriv…
Relativistic virial relation for cosmological structures
Reza Javadinezhad, Javad T. Firouzjaee, Reza Mansouri
Starting with the relativistic Boltzmann equation for a system of particles defined by a distribution function, we have derived the virial relation for a spherical structure within…
Cosmological black holes: the spherical perfect fluid collapse with pressure in a FRW background
Rahim Moradi, Javad T. Firouzjaee, Reza Mansouri
We have constructed a spherically symmetric structure model in a cosmological background filled with perfect fluid with non-vanishing pressure as an exact solution of Einstein equa…
Particle creation from the quantum stress tensor
Javad T. Firouzjaee, George F. R. Ellis
Among the different methods to derive particle creation, finding the quantum stress tensor expectation value gives a covariant quantity which can be used for examining the back-rea…
Cosmic Matter Flux May Turn Hawking Radiation Off
Javad T. Firouzjaee, George F. R. Ellis
An astrophysical (cosmological) black hole forming in a cosmological context will be subject to a flux of infalling matter and radiation, which will cause the outer apparent horizo…