Astrophysical implications of the Asymptotic Safety Scenario in Quantum Gravity (2009)
In recent years it has emerged that the high energy behavior of gravity could be governed by an ultraviolet non-Gaussian fixed point of the (dimensionless) Newton's constant, whose behavior at high...
Arentoft, Torben, Kjeldsen, Hans, Bedding, Timothy R., Bazot, Michael, Christensen-Dalsgaard, Joergen, Dall, Thomas H., ...
We have carried out a multi-site campaign to measure oscillations in the F5 star Procyon A. We obtained high-precision velocity observations over more than three weeks with eleven telescopes, with...
Non-axisymmetric instability of axisymmetric magnetic fields (2008)
The MHD instabilities can generate complex field topologies even if the initial field configuration is a very simple one. We consider the stability properties of magnetic configurations containing a...
Primordial Entropy Production and Lambda-driven Inflation from Quantum Einstein Gravity (2008)
Bonanno, Alfio, Reuter, Martin
We review recent work on renormalization group (RG) improved cosmologies based upon a RG trajectory of Quantum Einstein Gravity (QEG) with realistic parameter values. In particular we argue that QEG...
Naso, Luca, Rezzolla, Luciano, Bonanno, Alfio, Paterno', L.
During the first 40 s after their birth, proto-neutron stars are expected to be subject to at least two types of instability: the convective instability and the neutron-finger one. Both instabilities...
Magnetic shear-driven instability and turbulent mixing in magnetized protostellar disks (2008)
Observations of protostellar disks indicate the presence of the magnetic field of thermal (or superthermal) strength. In such a strong magnetic field, many MHD instabilities responsible for turbulent...
Mass Inflation in a Rotating Charged Black Hole (2007)
The interior of a charged rotating black hole is analyzed in the presence of an ingoing and outgoing flux of gravitational waves. An explicit mass-inflation solution is found in the limit of...
Direct problem for a 2D transonic stellar wind from slowly rotating stars (2007)
Beskin Lebedev, Alfio Bonanno, K. Bormann
S 1 Direct problem for a 2D transonic stellar wind from slowly rotating stars V.S.Beskin P.N.Lebedev Physical Institute, Moscow Abstract The procedure of solving the direct problem for a transonic...
Coarse-Graining and Renormalization Group in the Einstein Universe (2007)
The Kadanoff-Wilson renormalization group approach for a scalar selfinteracting field theory generally coupled with gravity is presented. An average potential that monitors the fluctuations of the...
Stability of magnetic configurations containing the toroidal and axial fields (2007)
Stability properties of magnetic-field configurations containing the toroidal and axial field are considered. The stability is treated by making use of linear analysis. It is shown that the...
We evaluate the generation of magnetosonic waves in differentially rotating magnetized plasma. Differential rotation leads to an increase of the azimuthal field by winding up the poloidal field lines...
Bonanno, Alfio, Esposito, Giampiero, Rubano, Claudio, Scudellaro, Paolo
This paper studies the cosmological equations for a scalar field Phi in the framework of a quantum gravity modified Einstein--Hilbert Lagrangian where G and Lambda are dynamical variables. It is...
Hydromagnetic Instability in plane Couette Flow (2007)
We study the stability of a compressible magnetic plane Couette flow and show that compressibility profoundly alters the stability properties if the magnetic field has a component perpendicular to...
Entropy signature of the running cosmological constant (2007)
Bonanno, Alfio, Reuter, Martin
Renormalization group (RG) improved cosmologies based upon a RG trajectory of Quantum Einstein Gravity (QEG) with realistic parameter values are investigated using a system of cosmological evolution...
Compressibility and local instabilities of differentially rotating magnetized gas (2007)
We study the stability of compressible cylindrical differentially rotating flow in the presence of the magnetic field, and show that compressibility alters qualitatively the stability properties of...
Noether symmetry approach in matter-dominated cosmology with variable G and Lambda (2006)
Bonanno, Alfio, Esposito, Giampiero, Rubano, Claudio, Scudellaro, Paolo
In the framework of renormalization-group improved cosmologies, we use the Noether symmetry approach to get exact and general integration of the matter-dominated cosmological equations. This is...
Noether symmetry approach in pure gravity with variable G and Lambda (2006)
Bonanno, Alfio, Esposito, Giampiero, Rubano, Claudio, Scudellaro, Paolo
We find exact cosmological solutions when the Newton parameter and the cosmological term are dynamically evolving in a renormalization-group improved Hamiltonian approach. In our derivation we use...
Improved Action Functionals in Non-Perturbative Quantum Gravity (2005)
Bonanno, Alfio, Esposito, Giampiero, Rubano, Claudio
Models of gravity with variable G and Lambda have acquired greater relevance after the recent evidence in favour of the Einstein theory being non-perturbatively renormalizable in the Weinberg sense....
The s-process weak component: uncertainties due to convective overshooting (2005)
Costa, Vincenzo, Pumo, Maria Letizia, Bonanno, Alfio, Zappala', Rosario Aldo
Using a new s-nucleosynthesis code, coupled with the stellar evolution code Star2003, we performed simulations to study the impact of the convection treatment on the s-process during core He-burning...
Bonanno, Alfio, Esposito, Giampiero, Rubano, Claudio
Models of gravity with variable G and Lambda have acquired greater relevance after the recent evidence in favour of the Einstein theory being nonperturbatively renormalizable in the Weinberg sense....
Mean-field dynamo action in protoneutron stars (2003)
Bonanno, Alfio, Rezzolla, Luciano, Urpin, Vadim
We have investigated the turbulent mean-field dynamo action in protoneutron stars that are subject to convective and neutron finger instabilities. While the first one develops mostly in the inner...
Non-perturbative scaling in the scalar theory (2000)
A new approach to study the scaling behavior of the scalar theory near the Gaussian fixed point in $d$-dimensions is presented. For a class of initial data an explicit use of the Green's function of...
Quantum Gravity effects near the null black hole singularity (1998)
Bonanno, Alfio, Reuter, Martin
The structure of the Cauchy Horizon singularity of a black hole formed in a generic collapse is studied by means of a renormalization group equation for quantum gravity. It is shown that during the...
The Cauchy Horizon in Higher-derivative Gravity Theories (1998)
A class of exact solutions of the field equations with higher derivative terms is presented when the matter field is a pressureless null fluid plus a Maxwellian static electric component. It is found...
Two loop results from the derivative expansion of the blocked action (1997)
Bonanno, Alfio, Zappala', Dario
A derivative expansion of the Wegner-Houghton equation is derived for a scalar theory. The corresponding full non-perturbative renormalization group equations for the potential and the wave-function...
Bonanno, Alfio, Zappalá, Dario
A renormalization group study of a scalar theory coupled to gravity through a general functional dependence on the Ricci scalar in the action is discussed. A set of non-perturbative flow equations...
Mass Inflation in a Rotating Charged Black Hole (1995)
The structure of the Cauchy horizon of a charged rotating black hole is analyzed under the combined effect of an ingoing and outgoing flux of gravitational waves. In particular, by means of an...
Coarse-Graining and Renormalization Group in the Einstein Universe (1995)
The Kadanoff-Wilson renormalization group approach for a scalar self-interacting field theor generally coupled with gravity is presented. An average potential that monitors the fluctuations of the...