Necrozma could also be a Pokémon embodying the power, or at least some features of a Black Hole, as black holes are known to refract light in some instance. The word "Necro" also deviates to meanings such as violent death, disappearance, perishing, etc, etc. Its also said to be a extremely violent Pokémon that constantly shoots out lasers, which could be lead to the idea of quasars, which are gigantic stream-like beams of electromagnetic energy that a Black Hole projects at times and are extremely luminous of nature.
It could also be representing the phenomena of Eclipses, as leaks pointed out it can learn Moonlight and Morning Sun respectively.