In many models, dark matter particles can elastically scatter with nuclei in planets, causing those particles to become gravitationally bound. While the energy expected to be released through the subsequent annihilations of dark matter particles in the interior of the Earth is negligibly small (a few megawatts in the most optimistic models), larger planets that reside in regions with higher densities of slow moving dark matter could plausibly capture and annihilate dark matter at a rate high enough to maintain liquid water on their surfaces, even in the absence of additional energy from starlight or other sources. On these rare planets, it may be dark matter rather than light from a host star that makes it possible for life to emerge, evolve, and survive.
In this paper, we have calculated the capture rate of dark matter particles in Earth-like and super-Earth planets, and determined the resulting surface temperature of those planets that would result from dark matter annihilations. While planets in the local region of our galaxy receive only a negligible quantity of energy from dark matter annihilations, we fi nd that planets in dwarf spheroidal galaxies and in the innermost volume of the Milky Way could plausibly accumulate and annihilate enough dark matter to heat their surfaces to temperatures capable of sustaining liquid water, even in the absence of energy from starlight or other standard sources.
Although we expect ecologically relevant quantities of energy to be released through dark matter annihilations only within the interiors of planets that reside in very special environments (such as near the Galactic Center, or near the center of a dwarf spheroidal galaxy), and only in the case of dark matter models which feature large elastic scattering cross sections with nuclei (near the current upper limits), we expect that within such models planets will exist which derive enough heat from dark matter to almost inde finitely sustain surface temperatures sufficient to yield liquid water. Even in the absence of starlight, such planets could plausibly contain life. And, given their extremely long lifetimes, such planets may prove to be the ultimate bastion of life in our universe.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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