Publication date: Jun 2016
Abstract:
We study electrically charged perfect fluid toroidal structures
encircling a spherically symmetric gravitating object with Schwarzschild
spacetime geometry and endowed with a dipole magnetic field. The work
represents a direct continuation of our previous general-relativistic
studies of electrically charged fluid in the approximation of zero
conductivity, which formed tori around a Reissner-Nordström black hole
or a Schwarzschild black hole equipped with a test electric charge and
immersed in an asymptotically uniform magnetic field. After a general
introduction of the zero-conductivity charged fluid model, we discuss a
variety of possible topologies of the toroidal fluid configurations.
Along with the charged equatorial tori forming interesting coupled
configurations, we demonstrate the existence of the off-equatorial tori,
for which the dipole type of magnetic field seems to be necessary. We
focus on orbiting structures with constant specific angular momentum and
on those in permanent rigid rotation. We stress that the general
analytical treatment developed in our previous works is enriched here by
the integrated form of the pressure equations. To put our work into an
astrophysical context, we identify the central object with an
idealization of a nonrotating magnetic neutron star. Constraining ranges
of its parameters and also parameters of the circling fluid, we discuss
a possible relevance of the studied toroidal structures, presenting
along with their topology also pressure, density, temperature and charge
profiles.
Authors:
Kovář, Jiří; Slaný, Petr; Cremaschini, Claudio; Stuchlík, Zdeněk; Karas, Vladimír; Trova, Audrey;