| MadSci Network: Astronomy |
Interesting question! And the answer is yes.
In fact, an example of this was recently discovered, practically
in our "backyard": the nearby giant elliptical galaxy Centaurus A
has been observed (with an infrared telescope) to have a small
spiral galaxy at its center,
as seen here.
It has long been thought that this galaxy, Cen A, once had a collision
(or "merger") with a small spiral galaxy.
This new image indicates that some remnants of the small galaxy
may have found their way to the center of the big galaxy,
forming the new spiral galaxy that we see today.
Since galaxy mergers are thought to be a common occurrence,
it is quite possible that there are many other
"galaxies-within-galaxies" out there.
Some more information about Cen A can be found
here,
here,
and
here.
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