Shining a Light on Dark Matter

The objective of our project is to understand the mystery that is dark matter, a key area of physics and cosmology in particular. Not only does dark matter contribute to a significant part of the composition of the universe (around 27%), dark matter also remains an elusive and unknown quantity. Our research into the topic mostly comes from a cosmological standpoint, but the studying of dark matter does require a broad knowledge base. From experimental particle physics looking at the very small, up through astrophysics and into the Universe-wide scale that we explore through cosmology, this report aims to explore many aspects of the subject. Through looking at galaxy rotation curves and dark matter halos, the implications of hot and cold dark matter and the candidate particles associated with them, and the direct and indirect detection of dark matter, this report aims to validate, or reject, the major theories of dark matter.

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To investigate the issue of galaxy rotations curves

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To investigate the concepts of hot and cold dark matter

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To look at the possible candidates for dark matter

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To explore the methods used to detect dark matter

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To understand the impact of dark matter on modern cosmology

The rotation curve of a galaxy is a graphical plot of the velocities of matter within the galaxy in comparison to their radius. The galaxy is usually assumed to be a disc galaxy. Kepler’s laws are used to estimate the velocity of matter at a given radius:

\begin{equation} v=\sqrt{\frac{GM}{r}}.\\ \end{equation}Once outside the inner core of the galaxy, the density of matter can be approximated with the relationship

\begin{equation} \rho\propto\frac{1}{r},\\ \end{equation}giving the rotation curve as shown: