Detecting Planets Made of Dark Matter: Is It Possible?
Planetary systems similar to our Solar System are rare, but they all appear to be made of ordinary matter, which is the same matter that makes up our own planetary system.
However, it is possible that some planets are made of particles that exist outside the Standard Model, such as dark matter.
Whether or not such planets exist is still unknown, and it is impossible to determine with our current knowledge.
To address this question, a group of scientists led by Yang Bai from the University of Wisconsin-Madison investigated how these hypothetical planets would appear and whether we could detect them.
The team concluded that it is possible to detect planets made of dark matter, but only under specific circumstances, which they outlined in a paper published on the arXiv preprint server.
Despite the many mysteries that remain in the Universe, one of the most significant is the nature of dark matter. We do not know what dark matter is or what it looks like, but we do know that the amount of gravity in the Universe exceeds the amount of baryonic matter, which is the only type of matter that we can currently observe.
Detecting Dark Exoplanets: Could Macros Be Out There?
Despite accounting for all observable matter in the Universe, there is still an excess of gravity that cannot be explained by what we can see. This phenomenon is attributed to dark matter, which is a mysterious source that scientists are currently investigating.
There are two categories of dark matter candidates: single particles and composites. The latter category includes Macros, which are macroscopic blobs of dark matter with planet-scale masses. According to Bai and his team, a Macro with a mass and/or radius similar to a planet could act like a dark exoplanet if it is bound to a star system.
Current methods of detecting exoplanets rely mainly on the effects that they have on the light of their host star. By observing the depth of the dimming caused by an exoplanet passing between us and its star, astronomers can calculate its radius. Changes in the wavelength of the star’s light, caused by the motion of the star and exoplanet around their mutual center of gravity, can also be used to calculate the exoplanet’s mass.
If Macros do exist and behave like dark exoplanets, then they could be detected using these same methods. However, the researchers note that certain conditions must be met in order for the detection to be successful.
These conditions include the mass and radius of the Macro, as well as its distance from its host star. The researchers also suggest that detecting a dark exoplanet made of Macros could provide insights into the nature of dark matter and its interactions with baryonic matter.
Overall, the search for dark exoplanets made of Macros remains a theoretical pursuit, but the possibility of their existence opens up a new avenue for investigating the mysterious nature of dark matter.
Detecting Dark Matter Exoplanets
Exoplanet properties can be determined by observing their effects on the light of their host star. By measuring the depth of the dimming of the star’s light, astronomers can calculate the radius of an exoplanet during a transit. Exoplanets also cause their stars to move slightly as they orbit, which is detectable in changes in the wavelength of the star’s light, known as radial velocity. These measurements can be used to calculate the exoplanet’s mass.
These measurements can also be used to calculate an exoplanet’s density, allowing scientists to determine how it is constructed. A low density implies a huge, low-density atmosphere, similar to that of Jupiter, whereas a higher density implies a rocky composition like Earth. Typically, low-density planets have larger radii and high-density planets have smaller radii.
Researchers led by Yang Bai of the University of Wisconsin-Madison suggest that these methods can also be used to detect potential dark matter exoplanets. A dark matter exoplanet might have different properties than expected from ordinary exoplanets, such as being denser than iron or so low-density that its existence is impossible to explain.
Currently, there have been no dark matter exoplanets identified. However, scientists are hopeful for the possibility of discovering one in the future.
Astronomers can also study the atmospheres of exoplanets by analyzing the spectrum of light from the star during transits. By comparing the transit spectrum to the normal spectrum of the star, they can determine what molecules are present in the exoplanet’s atmosphere. If the transit spectrum reveals some serious anomalies, that could indicate the presence of a dark matter exoplanet.
Identifying Dark Matter Exoplanets through Transit Observations
Astronomers can use transit observations to detect potential dark matter exoplanets. A transit occurs when an exoplanet passes in front of its star and causes the star’s light to dim, allowing astronomers to measure the exoplanet’s radius and mass based on the depth of the dimming and the motion of the star, respectively. By comparing the properties of dark matter exoplanets to those of ordinary exoplanets, scientists may be able to identify dark matter exoplanets that defy our current understanding of planet formation.
If an exoplanet’s radial velocity suggests that it should transit, but no transit is observed, it could be a clue pointing to the presence of a dark matter exoplanet. Additionally, an unexpected shape in the transit dip, known as the light curve, could indicate the existence of a dark matter exoplanet. Dark matter exoplanets may display a distinguishable light curve due to their tiny but non-vanishing interaction strength with Standard Model particles.
Bai and his colleagues have calculated the light curve of a dark matter exoplanet and laid down the groundwork for a more complex theoretical analysis. However, the team notes that their work only considers exoplanets in circular orbits and with relatively simple properties. Further study on dark matter exoplanet-stellar-system formation and capture would be necessary to set bounds on dark matter exoplanet abundance if they are not detected.