Dark Stars: A Brief Introduction

 The early universe was a very different place than it is now. But it may have been the perfect environment for a strange class of giant, puffy stars that used dark matter as fuel.Dark matter annihilations may have fueled some of the universe’s first stars, allowing them to grow into giant, puffy clouds that are millions of times the mass and billions of times the brightness of the Sun.Powered by dark matter, dark stars are hypothetical objects that may have inhabited the early universe. If they existed, these mysterious beasts would not only have been the first stars to form in the cosmos, they also might explain how supermassive black holes got their start.
The Dark Star can be explained in three different ways:
In case of dark matter - A dark star is a type of star that may have existed early in the universe before conventional stars were able to form. The stars would be composed mostly of normal matter, like modern stars, but a high concentration of neutralino dark matter within them would generate heat via annihilation reactions between the dark-matter particles. This heat would prevent such stars from collapsing into the relatively compact sizes of modern stars and therefore prevent nuclear fusion among the normal matter atoms from being initiated.

Under this model, a dark star is predicted to be an enormous cloud of hydrogen and helium ranging between 4 and 2000 astronomical units in diameter and with a surface temperature low enough that the emitted radiation would be invisible to the naked eye.

In the unlikely event that dark stars have endured to the modern era, they could be detectable by their emissions of gamma rays, neutrinos, and antimatter and would be associated with clouds of cold molecular hydrogen gas that normally would not harbor such energetic particles.

In Newtonian mechanics - A dark star is a theoretical object compatible with Newtonian mechanics that, due to its large mass, has a surface escape velocity that equals or exceeds the speed of light. Whether light is affected by gravity under Newtonian mechanics is unclear but if it were accelerated the same way as projectiles, any light emitted at the surface of a dark star would be trapped by the star's gravity, rendering it dark, hence the name. Dark stars are analogous to black holes in general relativity.

In case of dark energy -  A dark-energy star is a hypothetical compact astrophysical object, which a minority of physicists think might constitute an alternative explanation for observations of astronomical black holes candidates.

In the dark-energy star hypothesis, infalling matter approaching the event horizon decays into successively lighter particles. Nearing the event horizon, environmental effects accelerate proton decay. This may account for high-energy cosmic-ray sources and positron sources in the sky. When the matter falls through the event horizon, the energy equivalent of some or all of that matter is converted into dark energy. This negative pressure counteracts the mass the star gains, avoiding a singularity. The negative pressure also gives a very high number for the cosmological constant.