960 resultados para UNIFORM MAGNETIC-FIELD
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The observation of several neutron stars in the centre of supernova remnants and with significantly lower values of the dipolar magnetic field than the average radio-pulsar population has motivated a lively debate about their formation and origin, with controversial interpretations. A possible explanation requires the slow rotation of the protoneutron star at birth, which is unable to amplify its magnetic field to typical pulsar levels. An alternative possibility, the hidden magnetic field scenario, considers the accretion of the fallback of the supernova debris on to the neutron star as responsible for the submergence (or screening) of the field and its apparently low value. In this paper, we study under which conditions the magnetic field of a neutron star can be buried into the crust due to an accreting, conducting fluid. For this purpose, we consider a spherically symmetric calculation in general relativity to estimate the balance between the incoming accretion flow and the magnetosphere. Our study analyses several models with different specific entropy, composition, and neutron star masses. The main conclusion of our work is that typical magnetic fields of a few times 1012 G can be buried by accreting only 10−3–10−2 M⊙, a relatively modest amount of mass. In view of this result, the central compact object scenario should not be considered unusual, and we predict that anomalously weak magnetic fields should be common in very young (< few kyr) neutron stars.
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Work performed at Los Alamos Scientific Laboratory.
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"402-R-92-008."
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"ORINS-40; Particle accelerators and high-voltage machines."
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"Prepared for the Air Force Ballistic Missile Division, Headquarters Air Research and Development Command, under contract AF 04(647)-309 advanced propulsion systems."
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At head of title: PRL-9-23.
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"Prepared for the Air Force Ballistic Missile Division, Headquarters Air Research and Development Command, under contract AF04(647)-127, call no. 4."
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"February 1965."
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"AEC Contract AT(04-3)-400."
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"Contract N-onr-401-15."
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"AFOSR-1525."
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Mode of access: Internet.
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"This research was supported by the McDonnell Aircraft Corporation under Contract no.6140-20 P.O.7S4899-R."
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Spin precession due to Rashba spin-orbit coupling in a two-dimension electron gas is the basis for the spin field effect transistor, in which the overall perfect spin-polarized current modulation could be acquired. There is a prerequisite, however, that a strong transverse confinement potential should be imposed on the electron gas or the width of the confined quantum well must be narrow. We propose relieving this rather strict limitation by applying an external magnetic field perpendicular to the plane of the electron gas because the effect of the magnetic field on the conductance of the system is equivalent to the enhancement of the lateral confining potential. Our results show that the applied magnetic field has little effect on the spin precession length or period although in this case Rashba spin-orbit coupling could lead to a Zeeman-type spin splitting of the energy band.