Active Galaxies and
Quasars
1.
It is important to find the optical objects that correspond
in position with radio sources because we can then
a.
Observe their red shifts.
b.
Study their spectra to determine their
temperatures.
c.
Study their spectra to determine their
densities.
d.
All of these.
e.
None of these.
2.
In the largest telescopes, a quasar looks like
a.
a faint planet
b.
a star
c.
a dwarf galaxy
d.
a planetary nebula.
3.
The most conspicuous observed property of quasars is their
a.
low apparent magnitude (high apparent
brightness)
b.
high red shift*
c.
high blue shift
d.
dramatic appearance on photographs
e.
strong spiral structure.
4.
The red shifts of emission lines in quasar spectra are best
explained as caused by
a.
a large Doppler shift
b.
a strong gravitational field
c.
a black hole in the quasar
d.
rapid rotation
e.
turbulence in the nucleus.
5.
The best evidence that quasars are at cosmological distances
is
a.
their large observed red shift
b.
their association with clusters of
galaxies having the same red shift
c.
their association with clusters of
galaxies having a very different red shift
d.
their great luminosities
e.
their galaxy-like spectra.
6.
Why isn't the large red shift observed in quasars likely to
be a gravitational red shift? If the
large red shift observed for quasars was gravitational then quasars
a.
would have unusually large masses.
b.
should show effects of gravitational
attraction on other bodies.
c.
should show effects on the
"fuzz" surrounding them that decrease with an inverse square law.
d.
All of these.
e.
None of these.
7.
If the red shifts of
quasars arise from the expansion of the universe,
a.
a
quasar must be very small.
b.
a
quasar must be within the Local Group.
c.
a
quasar must be single star with an extremely large mass.
d.
a
quasar must be moving toward Earth with a large radial velocity.
e.
a
quasar must be very luminous.
8.
Quasars must be small
because they
a.
have
high radial velocities.
b.
are
very luminous.
c.
are
surrounded by quasar fuzz.
d.
radiate
huge amounts of energy.
e.
fluctuate
rapidly.
9.
The active region of a quasar whose light output varies
considerably in a month is
a.
a light-month in size
b.
a light-year in size
c.
a parsec in size
d.
the size of the Milky Way
e.
unknown in size.
10. Since quasars
are at great distances with the light taking a long time to reach us, we are
observing ______ objects.
a.
old
b.
young
c.
medium age
d.
dying
e.
no statement concerning age may be
made.
11. The discovery of the gravitational lens effect for
quasars
a.
shows
that quasars were located within the local group of galaxies.
b.
shows
that quasars were giant elliptical galaxies at very great distances.
c.
shows
that quasars are much further away than the distant galaxy that forms the
gravitational lens.
d.
proves
Newton's theory of gravitation by showing that the photon was affected by
gravity.
e.
proves
the existence of super massive black holes at the center of active galactic
nuclei.
12. When the radio
appearance of a typical radio galaxy is compared with its optical counterpart,
the radio object looks like
a.
a tadpole
b.
a jellyfish
c.
waterwings
d.
a spiral galaxy.
13. The radio
emission in a typical radio galaxy is produced by ______ emission.
a.
thermal
b.
synchrotron
c.
black hole
d.
cyclotron
e.
thermonuclear.
14. If an object
is observed to be emitting synchrotron radiation, we may conclude that
a.
it has a very high temperature
b.
it has a very low temperature
c.
the object is moving near the speed of
light
d.
the object has a strong magnetic field
e.
the object has no magnetic field.
15. The fact that many radio lobes emit more intensely
from the side away from the galaxy suggests that
a.
they
are formed by material falling into the galaxy.
b.
they
are powered by magnetic fields.
c.
they are
excited by radiation from nearby galaxies.
d.
they
are powered by the rapid rotation of the galaxy.
e.
they
are created by jets from the galaxy.
16. Seyfert
galaxies are characterized by
a.
weak reddish nuclei
b.
bright reddish nuclei
c.
weak bluish nuclei
d.
bright bluish nuclei.
17. BL Lac objects
a.
are galaxies with many properties of
quasars
b.
have two jets protruding from each side
c.
have some of the largest known red
shifts
d.
are found at the centers of quasars.
18. BL Lac objects
are known to be surrounded by a normal galaxy because
a.
the surrounding galaxy can be seen
visually through a telescope
b.
BL Lac objects emit strong emission
lines like a normal galaxy
c.
BL Lac objects vary in brightness just
like a normal galaxy
d.
the spectrum of the surrounding region
resembles that of a normal galaxy.
19. Which of the
following is NOT evidence of violent activity in the Milky Way and other
galaxies?
a.
nonthermal radiation from the nucleus
b.
large amounts of infrared radiation
coming from the center of the galaxy
c.
matter being ejected from the nucleus
d.
the nuclei of galaxies spin very
rapidly
20. The unified model describes active galactic nuclei using
a.
a
super massive black hole at the center of a normal spiral galaxy.
b.
a
super massive black hole surrounded by an accretion disk and dense disk of gas.
c.
an accretion
disk around a neutron star.
d.
gravitational
lenses to intensify the radiation coming from them.
e.
different
lines of sight toward and dwarf irregular galaxy.
21. By comparing
and contrasting quasars, active galaxies, and the Milky Way, we might conclude
that
a.
all are essentially the same thing,
except that quasars are larger than active galaxies
b.
these objects represent an evolutionary
sequence, showing that galaxies tend to become less violent as the universe
ages
c.
galaxies and similar objects were
smaller in the distant past than they are today
d.
objects which are farther away tend to
be brighter