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Lecture 3 Quiz

Lecture 3 Quiz. February 9, 2013 @ 11:00 am. T he unusually bright centers found in some galaxies are called . a ctive galactic nuclei. s tarbursts. h alos. s upermassive black holes. According to current understanding, what is a quasar?.

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Lecture 3 Quiz

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  1. Lecture 3 Quiz February 9, 2013 @ 11:00 am

  2. The unusually bright centers found in some galaxies are called • active galactic nuclei. • starbursts. • halos. • supermassive black holes.

  3. According to current understanding, what is a quasar? • An active galactic nucleus that is particularly bright. • Any object with an extremely large redshift. • A galaxy with an unusually high rate of star formation. • A very large galaxy thought to be formed by the merger of several smaller galaxies, typically found in the center of a galaxy cluster.

  4. The luminosity of a quasar is generated in a region the size of • the Milky Way. • a star cluster. • the solar system. • a planet.

  5. The observed relationship between the masses of central black holes and the bulge masses of galaxies implies that • the black holes will eventually suck in the rest of the galaxy. • the biggest galaxies have the most luminous quasars. • quasars were more common 10 billion years ago than they are today. • galaxy formation and supermassive black holes formation must be related somehow.

  6. The best evidence for the existence of supermassive black holes is • large quantities of high-energy emission, such as X-rays and gamma rays, and radio emission from relativistic electrons. • jet velocities that approach the speed of light. • huge dark regions in the centers of galaxies, where black holes have been sucking in the galaxy from the inside out. • very high orbital velocities in a very compact region.

  7. A quasar’s spectrum is hugely redshifted. What do most astronomers think this large redshift tells us about the quasar? • The size of the quasar’s central supermassive black hole. • The type of host galaxy in which the quasar resides. • The composition of the quasar. • The distance to the quasar.

  8. Most active galactic nuclei are found at large distances from us, with relatively few nearby. What does this imply? • Supermassive black holes existed only when the universe was young, and no longer exist today. • The jets seen in many active galactic nuclei must cause them to move far away from us. • Active galactic nuclei tend to become less active as they age. • Active galactic nuclei can form only at large distances from the Milky Way.

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