Primordial planets predominantly of dark Matter

Abstract

Cosmic structure formation is thought to occur as a bottom-up scenario, i.e. the lightest objects would have formed first. It has been suggested that the earliest structures to form could have been primordial planets. Here we propose the possibility of formation of primordial planets at high redshifts composed predominantly of dark matter (DM) particles, with planetary masses ranging from Neptune mass to asteroid mass. Most of these primordial DM planets could be free floating without being attached to a host star and a substantial fraction could be present in the halo contributing to the DM. Here we suggest that the flux of DM particles could be significantly reduced as substantial number of DM particles are now trapped in such objects, perhaps accounting for the negative results seen so far in the ongoing DM detection experiments.

It is now generally believed that complex structures formed in the early universe less than a billion years after the initial big bang. The earliest stellar objects could have formed even perhaps two hundred million years after the expansion began. To form such objects, the dominant atoms present, i.e. of hydrogen and helium, had to form by recombination, so that the matter could gravitate. However, dark matter (DM), in the form of massive particles could have gravitated much earlier as they do not have this constraint of decoupling from radiation.