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

TL;DR

This paper reports the most stringent observational limits on the flux of hypothetical heavy compact objects called nuclearites, using sky photographs from the "Pi of the Sky" project, constraining their possible abundance and properties.

Contribution

It provides new upper limits on the isotropic and directional flux of nuclearites across a wide mass range, based on a novel analysis of sky survey data.

Findings

Established flux limits between 5.4×10⁻²⁰ and 2.2×10⁻²¹ cm⁻² s⁻¹ sr⁻¹ for masses 100 g to 100 kg.

Set directional flux limits assuming a static nuclearite sea in the Galaxy, between 1.5×10⁻¹⁸ and 2.1×10⁻¹⁹ cm⁻² s⁻¹.

Constrained models predicting heavy compact objects and their astrophysical or particle physics origins.

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.