Michael Rotondo
Sapienza University of Rome
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Featured researches published by Michael Rotondo.
Physics Letters B | 2011
Michael Rotondo; Jorge A. Rueda; Remo Ruffini; She-Sheng Xue
Abstract We present the self-consistent treatment of the simplest, nontrivial, self-gravitating system of degenerate neutrons, protons and electrons in β -equilibrium within relativistic quantum statistics and the Einstein–Maxwell equations. The impossibility of imposing the condition of local charge neutrality on such systems is proved, consequently overcoming the traditional Tolman–Oppenheimer–Volkoff treatment. We emphasize the crucial role of imposing the constancy of the generalized Fermi energies. A new approach based on the coupled system of the general relativistic Thomas–Fermi–Einstein–Maxwell equations is presented and solved. We obtain an explicit solution fulfilling global and not local charge neutrality by solving a sophisticated eigenvalue problem of the general relativistic Thomas–Fermi equation. The value of the Coulomb potential at the center of the configuration is e V ( 0 ) ≃ m π c 2 and the system is intrinsically stable against Coulomb repulsion in the proton component. This approach is necessary, but not sufficient, when strong interactions are introduced.
International Journal of Modern Physics D | 2007
Remo Ruffini; Michael Rotondo; She-Sheng Xue
We present an approach to analyze the electrodynamics of nuclear matter in bulk using the relativistic Thomas–Fermi equation. We generalize to the case of N ≃ (mPlanck/mn)3 nucleons of mass mn an approach well tested in very heavy nuclei (Z ≃ 106). Particular attention is given to implement the condition of charge neutrality globally on the entire configuration, versus the one usually adopted on a microscopic scale. As the limit N ≃ (mPlanck/mn)3 is approached the penetration of electrons inside the core increases and a relatively small tail of electrons persists leading to a significant electron density outside the core. Within a region of 102 electron Compton wavelength near the core, surface electric fields close to the critical value for pair creation by vacuum polarization effect develop. These results can have important consequences on the understanding of physical process in neutron star structures as well as on the initial conditions leading to the process of gravitational collapse to a black hole.
International Journal of Modern Physics D | 2011
Michael Rotondo; Remo Ruffini; She-Sheng Xue; Vladimir Popov
In a unified treatment we extrapolate results for neutral atoms with heavy nuclei to nuclear matter cores of stellar dimensions with mass numbers A ≈ (mPlanck/mn)3 ~ 1057. We give explicit analytic solutions for the relativistic Thomas–Fermi equation of Nn neutrons, Np protons and Ne electrons in beta equilibrium, fulfilling global charge neutrality, with Np = Ne. We give explicit expressions for the physical parameters including the Coulomb and the surface energies and we study as well the stability of such configurations. Analogous to heavy nuclei these macroscopic cores exhibit an overcritical electric field near their surface.
Physical Review C | 2014
S. M. de Carvalho; Remo Ruffini; Jorge A. Rueda; Michael Rotondo
The Feynman-Metropolis-Teller treatment of compressed atoms has been recently generalized to relativistic regimes and applied to the description of static and rotating white dwarfs in general relativity. We present here the extension of this treatment to the case of finite temperatures and construct the corresponding equation of state (EOS) of the system; applicable in a wide regime of densities that includes both white dwarfs and neutron star outer crusts. We construct the mass-radius relation of white dwarfs at finite temperatures obeying this new EOS and apply it to the analysis of ultra low-mass white dwarfs with
arXiv: High Energy Astrophysical Phenomena | 2009
Remo Ruffini; Alexey G. Aksenov; Maria Grazia Bernardini; Carlo Luciano Bianco; Letizia Caito; Pascal Chardonnet; Maria Giovanna Dainotti; Gustavo De Barros; Roberto Guida; Luca Izzo; Barbara Patricelli; Luis Juracy Rangel Lemos; Michael Rotondo; Jorge Armando Rueda Hernandez; Gregory Vereshchagin; She-Sheng Xue
M\lesssim 0.2 M_\odot
International Journal of Modern Physics: Conference Series | 2012
Kuantay Boshkayev; Michael Rotondo; Remo Ruffini
. In particular, we analyze the case of the white dwarf companion of PSR J1738+0333. The formulation is then extrapolated to compressed nuclear matter cores of stellar dimensions, systems with mass numbers
arXiv: Astrophysics | 2008
Michael Rotondo; Remo Ruffini; She-Sheng Xue
A\approx (m_{\rm Planck}/m_n)^3
International Journal of Modern Physics D | 2011
Jorge A. Rueda; Michael Rotondo; Remo Ruffini; She-Sheng Xue
or mass
RELATIVISTIC ASTROPHYSICS: 5th Sino‐Italian Workshop on Relativistic#N#Astrophysics | 2008
Barbara Patricelli; Michael Rotondo; Remo Ruffini
M_{\rm core}\approx M_{\odot}
RELATIVISTIC ASTROPHYSICS: 4th Italian‐Sino Workshop | 2008
Michael Rotondo; Remo Ruffini; She Sheng Xue
, where