Ever since astronomers have been studying galaxies and their mass/luminosity relationship, there is clearly something wrong. There is a missing luminosity problem - there is a lot of non-luminous (about \(90 \%\)) matter in a galaxy. Possible dark matter candidates come from cold dark matter, warm dark matter, hot dark matter, and axions. After years of research, astronomers and physicists can rule out warm and hot dark matter, but cold dark matter and axions are both extremely probable candidates of dark matter. In this report, I will explain about all the different candidates of dark matter and their implications.
By studying the mass/luminosity of galaxies and planetary systems, it is clear that there is some mass missing. About \(10 \%\) of the mass is composed of luminous material, such as stars, and there is about \(90 \%\) of a galaxies mass unaccounted for. This non-luminous mass is called dark matter because it does not contribute to the total galaxies luminosity. Possible candidates for dark matter would be black holes, dwarf stars, different types of non-luminous gas, and planets. But, even after adding all of that mass together, there is still a huge portion of mass unaccounted for. We also know that dark matter must not interact via the electromagnetic force or we would have detected it by now. Also, we know it must interact with the gravitation force because we can see the gravitational effects of dark matter throughout the Universe. In this report, I will be studying possible dark matter candidates with a focus on cold dark matter.