What essential fuel source is generally lacking in elliptical galaxies, preventing active star birth?

Answer

Cold gas and dust

Elliptical galaxies are characterized by very little or no cold gas and dust. This material is the necessary raw ingredient for forming new stars, leading to a state where vigorous star formation has largely ceased.

What essential fuel source is generally lacking in elliptical galaxies, preventing active star birth?
galaxiesastronomystarsstellar evolutiongalaxy types