Strange Signal from the Center of the Milky Way: Dark Matter May Exist in Two States 0 7

At the center of the Milky Way, astronomers have discovered unusual gamma radiation, the most energetic form of light. One possible explanation is that dark matter particles collide and destroy each other, releasing energy in the process. However, the same signal has not appeared in other places where it should have. If dark matter is responsible for this radiation, why is it not detected in different galaxies? Scientists believe that dark matter may behave differently and its signals may depend on local conditions, manifesting in some galaxies while remaining unnoticed in others, writes Focus.

Dark matter is an invisible substance that is thought to hold galaxies together with its gravity. It can only be detected through its gravitational influence on ordinary matter, or, as in this case, through gamma radiation that is emitted when dark matter particles collide, scientists believe.

Dwarf galaxies that orbit the Milky Way are thought to contain a lot of dark matter and have a relatively low level of background radiation. This makes them ideal places to search for pure dark matter signals. If interactions between dark matter particles create gamma radiation in one large galaxy, similar signals should also be expected in smaller galaxies. However, these signals have not been detected.

The authors of the study believe this can be explained by the fact that dark matter models are incomplete. A new dark matter model suggests that this substance may consist of particles that have two closely related states — a lighter and a heavier one. For a signal to appear, particles in the lighter state need enough energy to transition to the heavier state before they can interact and produce gamma radiation.

In large galaxies like the Milky Way, dark matter particles move faster, giving them enough kinetic energy for this transition. After that, the interaction between the two states can create gamma radiation that telescopes detect.

In dwarf galaxies, particles move much slower. Without sufficient energy to reach the heavier state, these interactions become extremely rare, and effectively, the signal disappears. The same particles are present in both environments, but the local conditions are different.

The absence of signals in dwarf galaxies no longer contradicts the idea that dark matter may be behind the gamma radiation of the Milky Way, scientists say. As new data comes in, especially from dwarf galaxies, a better understanding of what dark matter can and cannot be will emerge.