UniverseTenth Edition

Chapter 24Quasars and Active Galaxies

Roger Freedman • Robert Geller • William Kaufmann III

iclicker Questions

Quasars are known to be distant objects (more than 100 Mpc away) because

A. they emit tremendous amounts of energy and thus cannot be nearby.

B. they have very small parallax angles. C. the Cepheid variables in them are very

dim. D. they have large redshifts. E. they have very low temperatures.

Q24.1

Quasars are known to be distant objects (more than 100 Mpc away) because

A. they emit tremendous amounts of energy and thus cannot be nearby.

B. they have very small parallax angles. C. the Cepheid variables in them are very

dim. D. they have large redshifts. E. they have very low temperatures.

A24.1

Quasar spectra are dominated by ______ lines, whereas the spectra of ordinary galaxies are dominated by ______ lines.

A. emission / absorption B. absorption / absorption C. emission / emission D. absorption / emissionE. absorption / x-ray emission

Q24.2

Quasar spectra are dominated by ______ lines, whereas the spectra of ordinary galaxies are dominated by ______ lines.

A. emission / absorption B. absorption / absorption C. emission / emission D. absorption / emissionE. absorption / x-ray emission

A24.2

In which region of the electromagnetic spectrum were quasars first observed?

A. Radio B. Infrared C. Visible D. Ultraviolet E. X-ray

Q24.3

In which region of the electromagnetic spectrum were quasars first observed?

A. Radio B. Infrared C. Visible D. Ultraviolet E. X-ray

A24.3

Synchrotron radiation has a spectrum that shows larger intensity for lower frequency. Such radiation has been observed to come from quasars and is produced byA. very hot objects. B. very cold objects. C. charged particles moving in a magnetic

field. D. charged particles moving in an electric

field. E. very hot objects moving in a magnetic

field.Q24.4

Synchrotron radiation has a spectrum that shows larger intensity for lower frequency. Such radiation has been observed to come from quasars and is produced byA. very hot objects. B. very cold objects. C. charged particles moving in a magnetic

field. D. charged particles moving in an electric

field. E. very hot objects moving in a magnetic

field.A24.4

By measuring the time for brightness fluctuations of a quasar, astronomers can place an upper limit on the quasar’s

A. luminosity. B. size. C. age. D. distance. E. temperature.

Q24.5

By measuring the time for brightness fluctuations of a quasar, astronomers can place an upper limit on the quasar’s

A. luminosity. B. size. C. age. D. distance. E. temperature.

A24.5

The Eddington limit is

A. the shortest wavelength radiation a black hole can emit.

B. the maximum mass of a black hole. C. the maximum diameter of a black hole. D. the maximum luminosity that matter

streaming into a black hole can emit.E. the minimum luminosity that matter

streaming into a black hole can emit. Q24.6

The Eddington limit is

A. the shortest wavelength radiation a black hole can emit.

B. the maximum mass of a black hole. C. the maximum diameter of a black hole. D. the maximum luminosity that matter

streaming into a black hole can emit.E. the minimum luminosity that matter

streaming into a black hole can emit. A24.6

An active galactic nucleus (AGN) is thought to be powered by

A. a supermassive black hole.B. supernovae.C. novae.D. luminous O and B stars.E. smaller dwarf galaxies within the AGN.

Q24.7

An active galactic nucleus (AGN) is thought to be powered by

A. a supermassive black hole.B. supernovae.C. novae.D. luminous O and B stars.E. smaller dwarf galaxies within the AGN.

A24.7

You observe an accretion disk surrounding the black hole at the center of an active galaxy. The accretion disk is viewed nearly edge-on. What do you see?A. A radio galaxyB. A quasarC. A blazar D. A pulsarE. A collapsar

Q24.8

You observe an accretion disk surrounding the black hole at the center of an active galaxy. The accretion disk is viewed nearly edge-on. What do you see?A. A radio galaxyB. A quasarC. A blazar D. A pulsarE. A collapsar

A24.8

You observe an accretion disk surrounding the black hole at the center of an active galaxy. The accretion disk is viewed nearly face-on. What do you see?A. A radio galaxyB. A quasarC. A blazar D. A pulsarE. A collapsar

Q24.9

You observe an accretion disk surrounding the black hole at the center of an active galaxy. The accretion disk is viewed nearly face-on. What do you see?A. A radio galaxyB. A quasarC. A blazar D. A pulsarE. A collapsar

A24.9

You observe an accretion disk surrounding the black hole at the center of an active galaxy. The accretion disk is viewed at a steep angle to the plane of its disk. What do you see?

A. A radio galaxyB. A quasarC. A blazar D. A pulsarE. A collapsar

Q24.10

You observe an accretion disk surrounding the black hole at the center of an active galaxy. The accretion disk is viewed at a steep angle to the plane of its disk. What do you see?

A. A radio galaxyB. A quasarC. A blazar D. A pulsarE. A collapsar

A24.10

A Seyfert galaxy is

A. a spiral galaxy with an active nucleus that is less luminous than a typical quasar.

B. a spiral galaxy with an active nucleus that is more luminous than a typical quasar.

C. an elliptical galaxy with an active nucleus that is less luminous than a typical quasar.

D. an elliptical galaxy with an active nucleus that is more luminous than a typical quasar.

E. another name for a radio-loud quasar.

Q24.11

A Seyfert galaxy is

A. a spiral galaxy with an active nucleus that is less luminous than a typical quasar.

B. a spiral galaxy with an active nucleus that is more luminous than a typical quasar.

C. an elliptical galaxy with an active nucleus that is less luminous than a typical quasar.

D. an elliptical galaxy with an active nucleus that is more luminous than a typical quasar.

E. another name for a radio-loud quasar.

A24.11