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Dark matter as a trigger for periodic comet impacts.

Lisa Randall1, Matthew Reece1

  • 1Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.

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|May 13, 2014
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Summary
This summary is machine-generated.

A potential 35-million-year impact cycle on Earth may be explained by a dark matter disk. This galactic structure could enhance meteorite impacts periodically, offering a new model for dark matter research.

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Area of Science:

  • Astrophysics and Planetary Science
  • Cosmology and Dark Matter Research

Background:

  • Statistical evidence suggests a possible ~35 million year periodicity in Earth's crater record, hinting at non-random impact events.
  • Previous explanations involving solar system passage through the galactic midplane face challenges with gravitational enhancement mechanisms and timing.

Purpose of the Study:

  • To propose and evaluate a novel model involving a smooth dark matter disk in the galactic midplane as an explanation for periodic meteorite impacts.
  • To assess the statistical significance of impact periodicity using a galactic model and compare it to a constant cratering rate.

Main Methods:

  • Developed a theoretical model incorporating a dissipative dark matter component forming a galactic disk.
  • Integrated astrophysical priors from the galactic model to statistically evaluate the evidence for impact periodicity.
  • Calculated the likelihood ratio comparing the dark disk model against a null hypothesis of constant impact rates.

Main Results:

  • The dark matter disk model provides a plausible mechanism for periodic gravitational enhancements causing increased impacts.
  • The likelihood ratio of 3.0 moderately favors the dark disk model over a constant cratering rate, considering astrophysical uncertainties.
  • Analysis suggests a dark matter disk surface density of approximately 10M⊙/pc² based on current geological data.

Conclusions:

  • A smooth dark matter disk in the galactic midplane offers a compelling explanation for the observed periodicity in Earth's crater record.
  • The geological evidence motivates a specific dark matter model that can be further investigated and tested with future observations.