scholarly journals Polytropic spheres with electric charge: Compact stars, the Oppenheimer-Volkoff and Buchdahl limits, and quasiblack holes

2013 ◽  
Vol 88 (8) ◽  
Author(s):  
José D. V. Arbañil ◽  
José P. S. Lemos ◽  
Vilson T. Zanchin
Keyword(s):  
Electric Charge ◽  
Compact Stars

scholarly journals Temperature oscillations of a gas moving close to circular geodesic in Reissner–Nordström spacetime

2019 ◽  
Vol 28 (04) ◽  
pp. 1950059 ◽  
Author(s):  
Leandro Cesar Mehret ◽  
Gilberto Medeiros Kremer
Keyword(s):  
Black Holes ◽  
Electric Charge ◽  
Periodic Oscillation ◽  
Compact Stars ◽  
Quark Stars ◽  
Temperature Oscillations ◽  
Inverse Effect ◽  
Low Mass ◽  
X Ray Binaries

The objective of this work is to analyze the temperature oscillations that occur in a gas in a circular motion under the action of a Reissner–Nordström gravitational field, verifying the effect of the charge term of the metric on the oscillations. The expression for temperature oscillations follows from Tolman’s law written in Fermi normal coordinates for a comoving observer. The motion of the gas is close to geodesic so the equation of geodesic deviation was used to obtain the expression for temperature oscillations. Then these oscillations are calculated for some compact stars, quark stars, black holes and white dwarfs, using values of electric charge and mass from models found in the literature. Comparing the various models analyzed, it is possible to verify that the role of the charge is the opposite of the mass. While the increase of the mass produces a reduction in the frequencies, amplitude and, in the ratio between the frequencies, the increase of the electric charge produces the inverse effect. In addition, it is shown that if the electric charge is proportional to the mass, the ratio between the frequencies does not depend on the mass, but only on the proportionality factor between charge and mass. The ratios between the frequencies for all the models analyzed (except for supermassive black holes in the extreme limit situations) are close to the [Formula: see text] ratio for twin peak quasi-periodic oscillation (QPO) frequencies, observed in many galactic black holes and neutron star sources in low-mass X-ray binaries.

scholarly journals Effect of electric charge on anisotropic compact stars in conformally symmetric spacetime

2018 ◽  
Vol 2 (1) ◽  
pp. 015002 ◽  
Author(s):  
Ksh Newton Singh ◽  
Piyali Bhar ◽  
Farook Rahaman ◽  
Neeraj Pant
Keyword(s):  
Electric Charge ◽  
Compact Stars ◽  
Symmetric Spacetime

scholarly journals Structural properties of charged compact stars with color-flavor-locked quarks matter

2021 ◽  
Author(s):  
M. K. Jasim ◽  
Anirudh Pradhan ◽  
Ayan Banerjee ◽  
Takol Tangphati ◽  
Grigoris Panotopoulos
Keyword(s):  
Equation Of State ◽  
Structural Properties ◽  
Electric Charge ◽  
Mass Density ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Central Mass ◽  
Quark Stars ◽  
The Impact ◽  
Tov Equation

The observations of pulsars with masses close to [Formula: see text] have put strong constraints on the equation-of-state (EoS) of neutron-rich matter at supranuclear densities. Moreover, the exact internal composition of those objects is largely unknown to us. Aiming to reach the [Formula: see text] limit, here we investigate the impact of electric charge on properties of compact stars assuming that the charge distribution is proportional to the mass density. The study is carried out by solving the Tolman–Oppenheimer–Volkoff (TOV) equation for a well-motivated exotic quark matter in the color-flavor-locked (CFL) phase of color superconductivity. The existence of the CFL phase may be the true ground state of hadronic matter with the possibility of the existence of a pure stable quark star (QS). Concerning the equation-of-state, we obtain structural properties of quark stars and compute the mass, the radius as well as the total electric charge of the star. We analyze the dependence of the physical properties of these QSs depending on the free parameters with special attention on mass–radius relation. We also briefly discuss the mass versus central mass density [Formula: see text] relation for stability, the effect of electric charge and compactness. Finally, our results are compared with the recent observations data on mass–radius relationship.

Charged anisotropic compact stars in Logarithmic-Corrected R2 gravity

2020 ◽  
Vol 35 (04) ◽  
pp. 2050013 ◽  
Author(s):  
M. Farasat Shamir ◽  
I. Fayyaz
Keyword(s):  
Energy Density ◽  
Electric Charge ◽  
Graphical Representation ◽  
Strong Electric Field ◽  
Compact Star ◽  
Compact Stars ◽  
Fluid Distribution ◽  
Anisotropic Fluid ◽  
Distribution Factor ◽  
Field Equations

We consider [Formula: see text] corrected model, i.e. [Formula: see text], where [Formula: see text] is the Ricci scalar and [Formula: see text], [Formula: see text] are arbitrary constant values, to investigate some of the interior configurations of static anisotropic spherical charged stellar structures. The existence of electric charge and a strong electric field confirms due to the higher values of pressure distribution and energy density of the matter inside the stars. Furthermore, for compact star configurations, we also consider the simplified MIT bag model equation of state (EoS) given by [Formula: see text], where [Formula: see text] is radial pressure, [Formula: see text] is energy density and [Formula: see text] is bag constant. This approach allows to find electric charge from the Einstein–Maxwell field equations. We have extensively discussed the behavior of the electric charge and anisotropic fluid distribution factor for five different values of [Formula: see text]. Interestingly, it is noticed during this study, for smaller values of [Formula: see text] we get intensity in electric charge. The Tolman–Oppenheimer–Volkoff equation (TOV), is modified in order to carry electric charge. In particular, we model the compact star candidates SAXJ 1808.4–3658 and Vela X-1 and give graphical representation of some important properties such as equilibrium condition, mass-radius ratio and surface redshift. In the end, our calculated solutions provide strong evidences for more realistic and viable charged stellar model.

scholarly journals Effect of electric charge on conformal compact stars

2019 ◽  
Vol 79 (1) ◽  
Author(s):  
P. Mafa Takisa ◽  
S. D. Maharaj ◽  
L. L. Leeuw
Keyword(s):  
Electric Charge ◽  
Compact Stars

Quantum 20/20

2019 ◽  
Author(s):  
Ian R. Kenyon
Keyword(s):  
Quantum Mechanics ◽  
Hall Effect ◽  
Particle Physics ◽  
Quantum Spin ◽  
Lessons Learned ◽  
Compact Stars ◽  
Einstein Condensation ◽  
Local Conservation ◽  
Variable Theory ◽  
Quantum Gauge Theory

This text reviews fundametals and incorporates key themes of quantum physics. One theme contrasts boson condensation and fermion exclusivity. Bose–Einstein condensation is basic to superconductivity, superfluidity and gaseous BEC. Fermion exclusivity leads to compact stars and to atomic structure, and thence to the band structure of metals and semiconductors with applications in material science, modern optics and electronics. A second theme is that a wavefunction at a point, and in particular its phase is unique (ignoring a global phase change). If there are symmetries, conservation laws follow and quantum states which are eigenfunctions of the conserved quantities. By contrast with no particular symmetry topological effects occur such as the Bohm–Aharonov effect: also stable vortex formation in superfluids, superconductors and BEC, all these having quantized circulation of some sort. The quantum Hall effect and quantum spin Hall effect are ab initio topological. A third theme is entanglement: a feature that distinguishes the quantum world from the classical world. This property led Einstein, Podolsky and Rosen to the view that quantum mechanics is an incomplete physical theory. Bell proposed the way that any underlying local hidden variable theory could be, and was experimentally rejected. Powerful tools in quantum optics, including near-term secure communications, rely on entanglement. It was exploited in the the measurement of CP violation in the decay of beauty mesons. A fourth theme is the limitations on measurement precision set by quantum mechanics. These can be circumvented by quantum non-demolition techniques and by squeezing phase space so that the uncertainty is moved to a variable conjugate to that being measured. The boundaries of precision are explored in the measurement of g-2 for the electron, and in the detection of gravitational waves by LIGO; the latter achievement has opened a new window on the Universe. The fifth and last theme is quantum field theory. This is based on local conservation of charges. It reaches its most impressive form in the quantum gauge theories of the strong, electromagnetic and weak interactions, culminating in the discovery of the Higgs. Where particle physics has particles condensed matter has a galaxy of pseudoparticles that exist only in matter and are always in some sense special to particular states of matter. Emergent phenomena in matter are successfully modelled and analysed using quasiparticles and quantum theory. Lessons learned in that way on spontaneous symmetry breaking in superconductivity were the key to constructing a consistent quantum gauge theory of electroweak processes in particle physics.

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