61 citations · 337 across the 28 of their papers we have counts for
28 papers · 1 filter
Dynamics of quadratic f(R) cosmology with a perfect fluid: Jordan and Einstein frames
Artur Alho, Margarida Lima, Filipe C. Mena
We investigate the global dynamics of the field equations of (pure) quadratic theories of gravity which generalise Einstein's theory in spatially flat homogeneous and isotropic cos…
Quintessence: Quadratic potentials
Artur Alho, Claes Uggla
Arguably one can use a canonical scalar field , minimally coupled to gravity, with quadratic potentials to explore some general features of slow-roll a…
Quintessence
Artur Alho, Elsa Bernholm, Claes Uggla
Recent observations suggest that the accelerated expansion of the Universe at late times is caused by a temporally changing dark energy component, rather than the constant one in t…
New simple and accurate quintessence approximations
Artur Alho, Claes Uggla
We derive new approximations for quintessence solutions that are simpler and an order of magnitude more accurate than anything available in the literature, which from an observatio…
Tracking Quintessence
Artur Alho, Claes Uggla, John Wainwright
Tracking quintessence, in a spatially flat and isotropic space-time with a minimally coupled canonical scalar field and an asymptotically inverse power-law potential $V(φ)\proptoφ^…
Spherically symmetric elastic bodies in general relativity
Artur Alho, José Natário, Paolo Pani +1
The purpose of this review it to present a renewed perspective of the problem of self-gravitating elastic bodies under spherical symmetry. It is also a companion to the papers [Phy…
Scale invariant elastic stars in General Relativity
Artur Alho, José Natário, Paolo Pani +1
We present a model of relativistic elastic stars featuring scale invariance. This implies a linear mass-radius relation and the absence of a maximum mass. The most compact spherica…
Quintessential -attractor inflation: A dynamical systems analysis
Artur Alho, Claes Uggla
The equations for quintessential -attractor inflation with a single scalar field, radiation and matter in a spatially flat FLRW spacetime are recast into a regular dynamical sys…
Dynamics of interacting monomial scalar field potentials and perfect fluids
Artur Alho, Vitor Bessa, Filipe C. Mena
Motivated by cosmological models of the early universe we analyse the dynamics of the Einstein equations with a minimally coupled scalar field with monomial potentials $V(ϕ)=\frac{…
Quintessence from a state space perspective
Artur Alho, Claes Uggla, John Wainwright
We use dynamical systems methods to study quintessence models in a spatially flat and isotropic spacetime with matter and a scalar field with potentials for which …
Compactness bounds in General Relativity
Artur Alho, José Natário, Paolo Pani +1
A foundational theorem due to Buchdahl states that, within General Relativity (GR), the maximum compactness of a static, spherically symmetric, perfec…
Cosmological global dynamical systems analysis
Artur Alho, Woei Chet Lim, Claes Uggla
We consider a dynamical systems formulation for models with an exponential scalar field and matter with a linear equation of state in a spatially flat and isotropic spacetime. In c…
Compact elastic objects in general relativity
Artur Alho, José Natário, Paolo Pani +1
We introduce a rigorous and general framework to study systematically self-gravitating elastic materials within general relativity, and apply it to investigate the existence and vi…
Dynamical systems in perturbative scalar field cosmology
Artur Alho, Claes Uggla, John Wainwright
We derive a new \emph{regular} dynamical system on a 3-dimensional \emph{compact} state space describing linear scalar perturbations of spatially flat Robertson-Walker geometries f…
Global dynamics of Yang-Mills field and perfect-fluid Robertson-Walker cosmologies
Artur Alho, Vitor Bessa, Filipe C. Mena
We apply a new global dynamical systems formulation to flat Robertson-Walker cosmologies with a massless and massive Yang-Mills field and a perfect-fluid with linear equation of st…
Perturbations of the Lambda-CDM model in a dynamical systems perspective
Artur Alho, Claes Uggla, John Wainwright
The observational success and simplicity of the CDM model, and the explicit analytic perturbations thereof, set the standard for any alternative cosmology. It therefore serves a…
The wave equation near flat Friedmann-Lemaître-Robertson-Walker and Kasner Big Bang singularities
Artur Alho, Grigorios Fournodavlos, Anne T. Franzen
We consider the wave equation, , in fixed flat Friedmann-Lemaître-Robertson-Walker and Kasner spacetimes with topology . We obtain gen…
Inflationary -attractor cosmology: A global dynamical systems perspective
Artur Alho, Claes Uggla
We study flat FLRW -attractor - and -models by introducing a dynamical systems framework that yields regularized unconstrained field equations on two-dim…
On dynamical systems approaches and methods in cosmology
Artur Alho, Sante Carloni, Claes Uggla
We discuss dynamical systems approaches and methods applied to flat Robertson-Walker models in -gravity. We argue that a complete description of the solution space of a model…
A stellar model with diffusion in general relativity
Artur Alho, Simone Calogero
We consider a spherically symmetric stellar model in general relativity whose interior consists of a pressureless fluid undergoing microscopic velocity diffusion in a cosmological…
Scalar field deformations of Lambda-CDM cosmology
Artur Alho, Claes Uggla
This paper treats nonrelativistic matter and a scalar field with a monotonically decreasing potential minimally coupled to gravity in flat Friedmann-Lemaître-Robertson-Walker c…
Global dynamics and asymptotics for monomial scalar field potentials and perfect fluids
Artur Alho, Juliette Hell, Claes Uggla
We consider a minimally coupled scalar field with a monomial potential and a perfect fluid in flat FLRW cosmology. We apply local and global dynamical systems techniques to a new t…
Dynamics of Robertson-Walker spacetimes with diffusion
Artur Alho, Simone Calogero, Maria P. Machado Ramos +1
We study the dynamics of spatially homogeneous and isotropic spacetimes containing a fluid undergoing microscopic velocity diffusion in a cosmological scalar field. After deriving…
Global dynamics and inflationary center manifold and slow-roll approximants
Artur Alho, Claes Uggla
We consider the familiar problem of a minimally coupled scalar field with quadratic potential in flat Friedmann-Lemaître-Robertson-Walker cosmology to illustrate a number of techni…