Orbital motion of primordial black holes crossing Solar-type stars

TL;DR

This paper investigates the complex orbital trajectories of low-mass primordial black holes captured by Sun-like stars, revealing diverse possible orbit shapes and behaviors due to interactions within stellar interiors.

Contribution

It introduces a detailed analysis of PBH trajectories inside stars, highlighting the effects of stellar mass interaction on orbit shape and stability, which was not previously explored.

Findings

PBH orbits can be open or closed depending on their interaction with stellar mass.

The shape of PBH trajectories varies significantly based on their position within the star.

Interactions within the star can lead to a variety of complex orbital patterns.

Abstract

Primordial black holes (PBHs) are hypothetical objects that could have originated from density fluctuations in a very early phase of our Universe. Recent observations restrict the masses that such PBHs could have, if they are to constitute all of dark matter today: $10^{17} \, {\rm g} \leq m \leq 10^{23} \, {\rm g}$. With such low masses, general relativity predicts that the corresponding radii for the PBHs would be atomic or subatomic in size. When captured by a star, such a tiny PBH could exhibit an orbit completely or partially inside the body of the star, without significantly changing its mass for quite a long time. Here we examine the possible trajectories of a PBH that is captured by a Sun-like star. When in motion in the interior of the star, the amount of stellar mass that effectively interacts with the PBH will be a function of its distance to the center of the star. As a consequence, a strong effect on the shape of the orbits emerges, leading to PBH trajectories that could be open or closed, and exhibiting a rich variety of patterns.