It is predicted to be sufficient for a net mass of normal matter equivalent to only a single galaxy in the known universe.

As the source is extended, with a size of about 45', this argues against the possibility that a single galaxy is responsible for the emission.

But what can a single galaxy do alone, without the help of a sister galaxy?

The main consequence is that, in determining the distance of a single galaxy, a possible error must be assumed.

Ultimately, the galaxies will merge to form a single giant elliptical galaxy.

Instead, they gradually merge to form a single, larger galaxy.

While looking for single galaxies, Cooke found something that at first appeared like a bright, single object.

In our single galaxy, at any single instant, is more than they can know or foresee.

It is a single galaxy in pair of galaxies.

The others were not concerned about a single galaxy.