Bound on the flux of magnetic monopoles from catalysis of nucleon decay inwhite dwarfs - art. no. 063007

Catalysis of nucleon decay in white dwarfs is used to constrain the abundan ce of magnetic monopoles arising from grand unified theories. Recent discov eries of the dimmest white dwarf ever observed, WD 1136-286 with L = 10(-4. 94)L., place limits on the monopole flux that are two orders of magnitude s tronger than previous bounds from white dwarfs. An abundance of monopoles g reater than the new bound would heat this star to a luminosity higher than what is observed. The new bound is (F/cm(-2) s(-1) sr(-1)) (sigma upsilon/1 0(-28) cm(2)) <1.3 X 10(-20)(upsilon(M)/10(-3) c)(2), where upsilon(M) is t he monopole velocity in the Galaxy. The limit is improved by including the monopoles captured by the main-sequence progenitor of the white dwarf: (F/c m(-2) s(-1) sr(-1)) (sigma upsilon/10(-28) cm(2)) < 3.5(26) X 10(-21) for 1 0(17) (10(16)) GeV monopoles. We also note that the dependence on monopole mass of flux bounds due to catalysis in neutron stars with main sequence ac cretion has previously been calculated incorrectly [previously the bound ha s been stated as F(sigma upsilon/10(-28) cm(2))<10(-28) cm(-2) s(-1) sr(-1) ]. We show that the correct bounds are somewhat weaker for monopole mass ot her than 10(17) GeV. [S0556-2821(99)05404-1].