Are there planets made of dark matter?
How can we locate them?
Our understanding of the solar system and all the star systems we know is based on the Standard Standard of physics. But are there planets made of other materials, particles that don’t belong to the Standard Model, like what we call dark matter? The answer is of course unattainable with our current knowledge, but a group of theoretical physicists at the University of Wisconsin-Madison wanted to know how such planets would form and how we might detect them if they were real.
Dark matter remains one of the universe’s greatest mysteries. We don’t know what it is, what it looks like, or what it consists of. All we know for sure is that the gravity in the universe is much greater than that resulting from baryonic matter.
Even if we take into account every galaxy, every star, and every cloud of dust in between, there is far more gravity than we can explain. Without knowing what is responsible for this, we have called this mystery dark matter, and scientists are investigating many models, which are mainly divided into two categories, individual particles and composites, such as macroscopic pockets of dark matter.
A macroscopic dark matter with a mass and/or radius similar to a planet will behave like a dark exoplanet if bound by a star system, even if the physical laws of the object are completely different.
The main method of detecting exoplanets today is the drop in brightness of a star when an exoplanet passes in front of it. By calculating the magnitude of the dip in brightness, astronomers can estimate the diameter of the exoplanet.
We can use the same method to detect possible dark matter exoplanets. A dark exoplanet will have different properties. It will probably be denser than iron or so low in density that its existence cannot be explained. More generally, any anomaly in the orbit, atmospheric signatures, or light may indicate the existence of a dark exoplanet.
Given the minimal but not absent interaction with the Standard Particle Model, the dark exoplanet may not be completely opaque, making the light curve indistinguishable from that of a normal exoplanet. Further study of the early formation of a dark exoplanet and star system, and the capture of a dark exoplanet, may help clarify the detectability of dark matter exoplanets and will be essential to constrain the abundance of dark exoplanets if they are not detected.
The paper is up for publication on arXiv .
