Neutron stars could be heating up from dark matter annihilation

One of many large mysteries about dark matter particles is whether or not they work together with one another. We nonetheless do not know the precise nature of what dark matter is. Some fashions argue that dark matter solely interacts gravitationally, however many extra posit that dark matter particles can collide with one another, clump collectively, and even decay into particles we will see. If that is the case, then objects with notably robust gravitational fields resembling black holes, neutron stars, and white dwarfs would possibly seize and focus dark matter. This might in flip have an effect on how these objects seem.

As a living proof, a examine seems on the interaction between dark matter and neutron stars. The examine is published on the arXiv preprint server.

Neutron stars are manufactured from probably the most dense matter within the cosmos. Their highly effective gravitational fields may entice dark matter and in contrast to black holes, any radiation from dark matter will not be trapped behind an event horizon. So neutron stars are an ideal candidate for learning dark matter fashions. For this examine, the crew checked out how a lot dark matter a neutron star may seize, and the way the decay of interacting dark matter particles would have an effect on its temperature.

The main points depend upon which particular dark matter mannequin you employ. Somewhat than addressing variant fashions, the crew checked out broad properties. Particularly, they targeted on how dark matter and baryons (protons and neutrons) would possibly work together, and whether or not that will trigger dark matter to be trapped. Certain sufficient, for the vary of attainable baryon-dark matter interactions, neutron stars can seize dark matter.

The crew then went on to have a look at how dark matter thermalization may happen. In different phrases, as dark matter is captured it ought to launch warmth power into the neutron star by means of collisions and dark matter annihilation. Over time the dark matter and neutron star ought to attain a thermal equilibrium.

The speed at which this happens is determined by how strongly particles work together, the so-called scattering cross-section. The crew discovered that thermal equilibrium is reached pretty shortly. For easy scalar fashions of dark matter, equilibrium might be reached inside 10,000 years. For vector fashions of dark matter, equilibrium can occur in only a yr. Whatever the mannequin, neutron stars can attain thermal equilibrium in a cosmic blink of an eye fixed.

If this mannequin is appropriate, then dark matter may play a measurable position within the evolution of neutron stars. We may, for instance, determine the presence of dark matter by observing neutron stars which are hotter than anticipated. Or even perhaps distinguish totally different dark matter fashions by the general spectrum of neutron stars.