How does gravitational lensing tell us about the mass of a galaxy cluster?
A)The lensing allows us to determine the orbital speeds of galaxies in the cluster,so that we can determine the mass of the cluster from the orbital velocity law.
B)The lensing broadens spectral lines,and we can use the broadening to "weigh" the cluster.
C)Using Einstein's general theory of relativity,we can calculate the cluster's mass from the precise way in which it distorts the light of galaxies behind it.
D)Newton's universal law of gravitation predicts how mass can distort light,so we can apply Newton's law to determine the mass of the cluster.

Question

Quizplus · Accepted Answer

Gravitational lensing occurs when the mass of a galaxy cluster bends the light passing through it, creating distortions or multiple images of a background object. By analyzing these distortions, we can use Einstein's general theory of relativity to calculate the mass of the galaxy cluster. The greater the mass of the cluster, the greater the distortion is expected to be. Therefore, by studying the lensing effect, we can estimate the mass of the galaxy cluster. Options A, B, and D are inaccurate and do not describe the process of gravitational lensing accurately.

How Does Gravitational Lensing Tell Us About the Mass of a Galaxy