Multiple Choice
What appears to be the central energy-generating system or "engine" that is producing prodigious amounts of energy in the centers of galaxies, active galaxies, and quasars?
A) steady series of supernova explosions, the late evolutionary stages of massive stars
B) rapidly rotating core of matter, where friction between it and the surrounding matter causes tremendous heat and energy output
C) supermassive black hole, where matter is compressed on falling into the hole and heated to extremely high temperatures
D) There is no central "engine" in these sources. Their high gravity has focused radiation from many sources beyond them by gravitational lensing and they thus appear to be very bright.
Correct Answer:

Verified
Correct Answer:
Verified
Q53: An active galaxy is measured to be
Q54: Cygnus A, a strong radio source, is
Q55: Observationally, the biggest difference between quasars and
Q56: What is an Einstein ring?<br>A) arc of
Q57: Astronomers initially had difficulty identifying the emission
Q59: The strongest direct evidence for supermassive black
Q60: When the jet of an active galaxy
Q61: What is the evidence that fast radio
Q62: Variations in the luminosity of quasars over
Q63: Which of these is NOT a characteristic