Limits on the flux of nuclearites and other heavy compact objects from the "Pi of the Sky" project

Abstract

Many theories predict the existence of very heavy compact objects, that in terms of sizes would belong to the realms of nuclear or atomic physics, but in terms of masses could extend to the macroscopic world, reaching kilograms, tonnes or more. If they exist, it is likely that they reach our planet with high speeds and cross the atmosphere. Due to their high mass to size ratio and huge energy, in many cases, they would leave behind a trail in the form of sound and seismic waves, etches, or light in transparent media. Here we show results of a search for such objects in visual photographs of the sky taken by the "Pi of the Sky" experiment, illustrated with the most stringent limits on the isotropic flux of incoming so-called nuclearites, spanning between $5.4\cdot10^{-20}$ and $2.2\cdot10^{-21}\ \mathrm{cm}^{-2} \mathrm{s}^{-1} \mathrm{sr}^{-1}$ for masses between 100 g and 100 kg. In addition we establish a directional flux limit under an assumption of static "sea" of nuclearites in the Galaxy, which spans between $1.5\cdot10^{-18}$ and $2.1\cdot10^{-19}\ \mathrm{cm}^{-2} \mathrm{s}^{-1}$ in the same mass range. The general nature of the limits presented should allow one to constrain many specific models predicting the existence of heavy compact objects and both particle physics and astrophysical processes leading to their creation, and their sources.