contestada

The speed at which spiral galaxies rotate is often remarkably constant with increasing distance from the center of the galaxy; i.e., the galaxy's rotation curve is remarkably flat. The significance of this is that spiral galaxies contain significant amounts of ____ matter which cannot be detected using electromagnetic radiation at any wavelength.

Respuesta :

Answer:

In this question, we have to fill the blank so, the blank is Dark.

Explanation:

Because in spiral galaxies the orbital velocity remains constant because of dark matter concentrated at the center. Then electromagnetic light can not detect them.