51.The fact that many radio lobes emit more intensely from : 1777267
51.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 emitting where the material is halted.
52.The central galaxy in a double-lobed radio source is usually
A.an irregular galaxy.
B.a spiral galaxy.
C.a dwarf elliptical galaxy.
D.a giant elliptical galaxy.
53.That the radio lobes radiate synchrotron radiation indicates that
A.high speed electrons are spiraling through a magnetic field.
B.the source of the radio jets must be a black hole.
C.the source of the radio energy is rotating rapidly.
D.the central galaxy must be a giant elliptical galaxy.
E.the central galaxy must rotate about two nearly perpendicular axes.
54.Centaurus A is a radio galaxy that has a visible galaxy at the center. This central elliptical galaxy of Centaurus A is encircled by a ring of gas and dust, different from most elliptical galaxies. The dust ring orbits about an axis that is perpendicular to the axis of rotation of the elliptical galaxy. What does this suggest about this central elliptical galaxy of Centaurus A?
A.The radio jets have caused the dust disk to be driven around the elliptical galaxy.
B.There are at least two black holes at the center of the elliptical galaxy.
C.Centaurus A is probably the result of a merger of an elliptical galaxy and a spiral galaxy.
D.Dust is produced as the jets interact with the intergalactic medium.
E.Elliptical galaxies often contain dust that forms a disk along their rotation axis.
55.If the red shifts of quasars arise from the expansion of the universe yet they have brighter magnitudes than galaxies with the same red shifts, the quasar must be
B.within the Local Group.
C.a single star with an extremely large mass.
D.be moving toward Earth with a large radial velocity.
E.emit a very large amount of energy per second.
56.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 on time scales as short as a few hours.
57.We suspect that quasars are the active centers of galaxies because
A.“fuzz” around the central luminous regions produces spectra like a collection of normal stars..
B.a few quasars have large red shifts.
C.the central regions of some quasars fluctuate rapidly.
D.all of the above
E.none of the above
58.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 planets in our solar system.
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.
59.Mid-sized black holes of a few thousand solar masses have been found in the cores of some
E.dark molecular clouds.
A.can be used to draw conclusions about a specific cases.
B.is applicable to classes of objects where only a few objects from the class have been studied.
C.allows scientists to determine the mechanism that produces the dust ring in Centaurus A.
D.allows scientists to deduce general characteristics about a class of objects with similar properties.
E.provides insight into the behavior of an individual object based on careful observations of it.