Question

Which of the following is NOT a piece of evidence for supermassive black holes (SMBHs) being at the centers of galaxies?

A. The presence of a bulge of stars at the center of the galaxy
B. The observation of jets of material being ejected from the centers of galaxies
C. The observation of stars orbiting very quickly around the centers of galaxies
D. The presence of a bright source of radiation at the center of the galaxy

Answer 1

Option A, the presence of a bulge of stars at the center of a galaxy, is not direct evidence for a supermassive black hole; rather, it is a correlated feature. Direct evidence includes the motion of stars, radiation from accretion disks, and material jets, indicating a highly dense central mass.

Step-by-step explanation:

The piece of evidence that is NOT for supermassive black holes (SMBHs) being at the centers of galaxies is A. The presence of a bulge of stars at the center of the galaxy. Although the mass of the central bulge of a galaxy does correlate with the mass of the SMBH at the center, the bulge itself is not direct evidence for a black hole. Evidence for SMBHs includes high-velocity stars orbiting the galaxy's center, accretion disks emitting intense radiation, and material jets ejecting from the core. All these phenomena suggest a mass that is so dense that nothing other than a SMBH could explain the gravitational forces at play.