On the compatibility of observable grand unified monopole fluxes and neutron stars

We consider the possibility that the constraints on grand unified monopole fluxes derived from limits on the X-ray background due to hot neutron stars, contain a window in the range 10-15 < or approx.Fsigma0 < or approx.10-13 cm-2 s-1 sr-1. The appearance of this window is due primarily to three effects: (1) neutron stars with large numbers of monopoles catalyzing baryon decay in their interiors are mainly producing neutrinos rather than photons; (2) the photons radiated are hard X-rays or γ-rays in which the background limits are slightly less restrictive, and (3) the lifetime of the neutron star is drastically reduced through disintegration (i.e., all the nucleons in the star will have been processed by monopoles). All of the arguments are sensitive to the equation of state inside the neutron star, leading to uncertainties which should not dissuade experimenters from monopole searches. (orig.)