Dark matter monopoles, vectors and photons
  In a secluded dark sector which is coupled to the Standard Model via a Higgs
portal interaction we arrange for the existence of 't Hooft-Polyakov magnetic
monopoles and study their implications for cosmology. We point out that a dark
sector which can accommodate stable monopoles will also contain massless dark
photons gamma' as well as charged massive vector bosons W'. The dark matter in
this scenario will be a combination of magnetically and electrically charged
species under the unbroken U(1) subgroup of the dark sector. We estimate the
cosmological production rate of monopoles and the rate of
monopole-anti-monopole annihilation and conclude that monopoles with masses of
few hundred TeV or greater, can produce sizeable contributions to the observed
dark matter relic density. We scan over the parameter space and compute the
relic density for monopoles and vector bosons. Turning to the dark photon
radiation, we compute their contribution to the measured density of
relativistic particles Neff and also apply observational constraints from the
Bullet cluster and other large scale galaxies on long-range interactions for
the self-interacting dark matter components made out of monopoles and out of
dark vector bosons. At scales relevant for dwarf galaxies we identify regions
on the parameter space where self-interacting monopole and vector dark mater
components can aid solving the core-cusp and the too-big-to-fail problems.
