Can the Strongly Interacting Dark Matter Be a Heating Source of Jupiter?

Abstract

We show that the strongly·interacting massive particle (SIMP) with mass of 3x10 6 -10 7 GeV is astrophysically interesting as a dark matter candidate the galactic halo. The annihilation of SIMPs inside Jupiter naturally explains the intrinsic heat flux irrespective of details of the planetary models. We discuss its effect in all Jovian planets as well as in the Sun and the Earth. We also comment that such a SIMP is accommodated in a class of hadronic axion models. The dark matter (for a recent review, see, e.g., Ref. 1)) giving a large fraction of the gravitational mass of the galaxy may be composed of elementary particles. These particles must be so weakly-interacting or so few and heavy that they are not conspicuous. Many dark-matter candidates have been proposed!) and the possibil­ ities of their experimental detection have been intensively studied. 2 ) Among them the strongly-interacting dark-matters 3 ) are very interesting since they may allow the direct detection in the dark-matter search experiments on the Earth. In fact, only small regions have been left open for the strongly-interacting massive particles h (SIMPs), one with mass of 10 5 -10 7 GeV and the other with mass above 1010 GeV. 3 ) Furthermore, the recent experiment by Caldwell et a1. 4 ) has excluded some portion of the window. However the SIMP with mass of 3 X 10 6 -10 7 Ge V is still allowed. *) In this paper we point out that for the window, SIMPs are trapped in the planets and can annihilate in their centers producing possible heating energies. We indeed find that our model may explain the mysteriously large intrinsic heat flux of Jupiter 5 ) within the three standard deviations irrespective of the detailed parameters of the planet as well as the annihilation cross section. However for other Jovian planets,6),7) one must require that the SIMP's annihilation has not yet reached the steady state, since otherwise it overproduces the heating energy. In this case the predicted heat fluxes depend on details of the densities and temperatures of the planet cores and the annihilation cross section. We also examine SIMP's annihilation effects in the Earth and the Sun. The final comment is devoted to stressing that this stable SIMP is naturally accommodated in a class of hadronic axion models. Our basic assumption is that the dark halo of our galaxy 'is a cloud of the SIMPs h with the mass density Ph=OA GeV fcm