‘Galaxies’ describes galaxy morphology, the chemical evolution of galaxies, and stellar dynamics. A galaxy consists of a huge number of point masses—stars and dark matter—that move freely in the gravitational field that they jointly generate. The nature of a galaxy is largely determined by its luminosity, its bulge-to-disc ratio, and the ratio of its mass of cold gas to the mass in stars. Galaxies are also shaped by their environments. Dense environments are rich in elliptical and lenticular galaxies, while abnormally under-dense environments are rich in dwarf irregular galaxies. Spiral galaxies like our own tend to inhabit regions of intermediate density.
Dark matter search in dwarf irregular galaxies with the
Fermi
Large Area Telescope
