Universal charge-radius relation for subatomic and astrophysical compact objects.
Electron-positron pair creation in supercritical electric fields limits the net charge of any static, spherical object, such as superheavy nuclei, strangelets, and Q balls, or compact stars like neutron stars, quark stars, and black holes. For radii between 4 x 10(2) and 10(4) fm the upper bound on the net charge is given by the universal relation Z=0.71R(fm), and for larger radii (measured in femtometers or kilometers) Z=7 x 10(-5)R_(2)(fm)=7 x 10(31)R_(2)(km). For objects with nuclear density the relation corresponds to Z approximately 0.7A(1/3)( (10(8)<A<10(12)) and Z approximately equal to 7 x 10(-5)A(2/3) (A>10(12)), where A is the baryon number. For some systems this universal upper bound improves existing charge limits in the literature.
Department of Physics and Astronomy, University of Aarhus, Arhus C, Denmark.
Jes
J
Madsen