What component of our galaxy contains only a small amount of interstellar medium?

The component of our galaxy that contains only a small amount of interstellar medium is the halo. The halo is the spherical region surrounding the galaxy that contains older stars, globular clusters, and dark matter, but it has very low densities of gas and dust compared to the more active regions like the disk. This lack of interstellar medium in the halo contrasts with the rich presence of gas and dust in the galaxy's disk, where new stars form.