With low light levels your brightest signal will be close to the noise floor, so you only really have three options:
- a camera with better low light performance (although this can only take you so far)
More expensive sensors can give a lower noise floor, allowing you to resolve more detail
As Jason commented:
If the widest aperture on your kit lens is 4.0, then you could double the amount of light your camera sees by purchasing an f2.8. Every additional "stop" doubles the light, so if you could find an f1.0, you'd be getting 16 times the light that f4.0 allows.
Your easiest option may be just to increase the illumination and then reduce brightness in post. Remember that if you do this, you also need to watch for shadows that look too sharp.