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arXiv:1909.11090hep-ph

What if Planet 9 is a Primordial Black Hole?

Jakub Scholtz, James Unwin

Abstract

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.

arXiv comments
7 pages, 1 exact scale illustration of a 5 Earth mass black hole
Journal reference
Phys. Rev. Lett. 125, 051103 (2020)
DOI
doi:10.1103/PhysRevLett.125.051103
Subjects
hep-phHigh Energy Physics, Phenomenology astro-ph.COCosmology and Nongalactic Astrophysics astro-ph.EPEarth and Planetary Astrophysics

On Hacker News

Linked by 10 identifiable commenters in 10 comments across 10 threads, from Sep 2019 to May 2025. Found in 3 HN submissions from Sep 2019 to Sep 2023. Open submission discussions.

Comments linking this paper, per year.

Discussed in comments10 threads

  1. Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart 1 comment

    • 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.

      snowwrestlerView on HNParent context

  2. Nasa’s Roman Mission Will Hunt for Primordial Black Holes 1 comment

    • - "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…

      perihelionsView on HNParent context

  3. New evidence found for Planet 9 1 comment

    • 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

      ben_wView on HNParent context

  4. A Dyson sphere around a black hole 1 comment
  5. What if Planet 9 is a Primordial Black Hole? (2019) 1 comment
  6. The case for, and against, the still-unseen Planet 9 1 comment
  7. A Black Hole at the Center of Earth 1 comment
  8. What if Planet 9 is a Primordial Black Hole? 1 comment

    • 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.

      ISLView on HNParent context

  9. Hubble Observes First Confirmed Interstellar Comet 1 comment

    • 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…

      SiempreViernesView on HNParent context

  10. What If Planet 9 Is a Primordial Black Hole? 1 comment

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