Jakub Scholtz, James Unwin
2019 · arXiv
We highlight that the anomalous orbits of Trans-Neptunian Objects (TNOs) and an excess in microlensing events in the 5-year OGLE dataset can be simultaneously explained by a new population of astrophysical bodies with mass several times that of Earth ($M_\oplus$). We take these objects to be primordial black holes (PBHs) and point out the orbits of TNOs would be altered if one of these PBHs was captured by the Solar System, inline with the Planet 9 hypothesis. Capture of a free floating planet is a leading explanation for the origin of Planet 9 and we show that the probability of capturing a PBH instead is comparable. The observational constraints on a PBH in the outer Solar System significantly differ from the case of a new ninth planet. This scenario could be confirmed through annihilation signals from the dark matter microhalo around the PBH.
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This paper exploring the idea has as Fig 1. a to-scale illustration of a 5-Earth-mass primordial black hole: https://arxiv.org/pdf/1909.11090 As I recall, it did not get printed this way because the ink would be too expensive, or mess with the paper.
- "In that case you'd see X-rays, gamma rays, etc., but maybe only briefly." One speculative possibility is that we could find a continuous gamma annihilation signal from its dark matter halo, https://arxiv.org/abs/1909.11090 https://hn.algolia.com/?query=What%20If%20Planet%209%20Is%20...
One of the options is that it's a primordial black hole, which leads to my favourite "actual size" caption on a diagram, page 5: https://arxiv.org/pdf/1909.11090
One should not miss Figure 1 of the arXiv preprint, which is, alas, absent from the final PRL. https://arxiv.org/pdf/1909.11090.pdf It is among the rarest journal-article figures in physics. If I'd been asked to referee the paper, I'd have campaigned hard to keep it in.
No, that paper says "What if Planet 9 is a Primordial Black Hole?" and then works out some consequences and finds them to be not ruled out. It doesn't start from observations and arrive at the PBH in any natural way. To judge for yourself hour serious the authors are in proposing a primordial black hole to explain the anomalies in the outer asteroid belt, I refer you to figure 1 in their paper: https://arxiv.org/pdf/1909.11090.pdf
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