What substance almost entirely constitutes the Dark Matter Halo, preventing it from interacting with the electromagnetic force?
Answer
Dark matter
The Dark Matter Halo is composed almost entirely of dark matter, which is defined by its lack of interaction with the electromagnetic force, meaning it neither emits nor absorbs light.

#Videos
What Elements Are Required to Form a Galaxy? - YouTube
Related Questions
What are the three primary, massive structural components used to define a galaxy's appearance and dynamics?Which structural component of a galaxy is primarily characterized by ongoing star formation and the presence of significant cold gas and dust?How is the motion of stars within the central bulge typically described, contrasting with the orderly rotation seen in the disk?What substance almost entirely constitutes the Dark Matter Halo, preventing it from interacting with the electromagnetic force?Which component accounts for the vast majority (often 80% to 90% or more) of a galaxy's total gravitational influence?Relative to the stars in the galactic disk, what is generally true about the age of the stellar population found in the central bulge?By what means is the existence and extent of the Dark Matter Halo primarily inferred by astronomers?What dictates the orbital speed of stars within the galactic disk as they circle the center?In the analogy comparing galaxy components to layers of an archaeological dig, which structure represents the deepest, oldest layer?What is a likely structural consequence observed in a galaxy that has experienced a major merger event involving two spirals?