Name: __________________________  Date: _____________

1.	The first three strong radio sources, discovered by Reber in the 1930s and 1940s, did not include	
A)	the galactic nucleus.	
B)	a supernova remnant.	
C)	a globular cluster.	
D)	a distant galaxy.	

2.	What is the most outstanding feature of a quasar compared to other objects in deep space?	
A)	Its small size	
B)	Its great distance from the Earth	
C)	Its short lifetime	
D)	Its prodigious output of energy	

3.	The specific characteristics that identify most quasars are	
A)	that they look like elliptical galaxies, but with high spectral redshifts.	
B)	bright, starlike appearance and very high spectral blueshift, indicating that they are approaching the Sun very fast, and rapid intensity fluctuations, indicating small intrinsic size.	
C)	bright, starlike appearance with very high redshifts and hence very large distances, indicating very energetic sources.	
D)	spiral galaxy appearance and very high spectral blueshift, indicating that they are coming toward the Sun at high speed.	

4.	Which observations of quasars convinced astronomers that they were very distant objects?	
A)	Their extremely red spectrum, reddened by extreme interstellar absorption of the blue part of the spectrum, meaning that the source must be a very long way away	
B)	Extreme redshift of visible Balmer and UV Lyman hydrogen emission lines, indicating high recessional velocities and hence, by the Hubble law, very large distances	
C)	Their extreme faintness at visible wavelengths, the inverse square law for visible light showing that they must be very distant	
D)	Their appearance as pointlike star images under the highest magnification, meaning that they must be very far away	

5.	What are the typical characteristics of a quasar in terms of energy generation?	
A)	The output of a 100 galaxies from a volume with diameter of 1 light-day	
B)	The output of a 106 galaxies from a volume with diameter of 1 light-day	
C)	The output of a 100 galaxies from a volume with diameter of 1 light-year	
D)	The output of a single galaxy from a volume with diameter of 1 light-year	

6.	What observations convince us that the energy source of a quasar is physically very small?	
A)	Rapid fluctuations in brightness since variations over 1 day mean that the source must be less than one light-day across	
B)	The instant disappearance of the quasar when occulted by the Moon's edge as the Moon moves in front of a quasar, indicating a very small source size	
C)	The sharpness of the emission lines in their optical spectra since motions within a large source would smear out the line shapes	
D)	The extremely small size of the image of a quasar, even from Hubble Space Telescope images and radio interferometry measurements	

7.	Seyfert galaxies are	
A)	elliptical galaxies with extremely bright nuclei.	
B)	supergiant elliptical galaxies that are periodically disturbed by supernova explosions within them.	
C)	spiral galaxies with extremely active cores.	
D)	active galaxies that shine mainly by radiation from two relatively widely spaced radio lobes.	

8.	BL Lacertae objects appear to be	
A)	giant irregular galaxies with neither spiral arms nor the smooth shape of elliptical galaxies.	
B)	elliptical galaxies with bright, starlike nuclei.	
C)	spiral galaxies with bright, starlike nuclei.	
D)	active galaxies, most of whose energy is emitted by two widely spaced radio lobes.	

9.	Which of the following will produce synchrotron radiation?	
A)	The accelerated motion of high-speed electrons as they spiral in a magnetic field	
B)	The heating of matter by compression as it spirals into a black hole	
C)	The radioactive decay of an atomic nucleus	
D)	The slowing down of charged particles as they enter a dense medium such as the atmosphere of a star or that of the Earth	

10.	What mechanism appears to produce the double radio sources seen in intergalactic space?	
A)	Two oppositely directed jets of matter, ejected from a small source	
B)	Two radio galaxies orbiting each other, much like two binary stars	
C)	A radio-bright galaxy with a dark absorbing disk edge-on to the Earth, splitting the source into two from our viewpoint	
D)	Two black holes orbiting around a small but massive galactic nucleus	

11.	What recent evidence seems to indicate that several nearby galaxies may contain supermassive black holes at their centers?	
A)	The rotation curve of these galaxies, which shows no decrease in orbital velocity of stars as the radius of orbit increases out to the observable limit of the galaxy, indicating an unusual source of gravity.	
B)	Spectroscopic observations of stars near the centers of these galaxies showing extremely fast orbital velocities, indicating the presence of a large mass to keep stars in orbit	
C)	Extreme redshift of light from stars near the centers of these galaxies caused by gravitational redshift from a very massive object	
D)	Observation that these galaxies are rushing rapidly toward each other (and in at least one case, toward the Milky Way!) because of the gravitational attraction between these very large masses	

12.	Observations indicate that BL Lacertae objects are	
A)	quasars colliding with smaller galaxies and initiating vigorous star formation.	
B)	black holes in binary star systems, where matter pulled from the companion stars forms a hot accretion disk around the black holes.	
C)	distant spiral galaxies with high rates of supernova explosions within them.	
D)	radio galaxies whose jets and radio lobes point almost directly at the Earth.	

13.	The central “engine” of an active galaxy appears to be	
A)	stars falling into a supermassive black hole, their remnants being thrown out in all directions.	
B)	supernova explosions in an extremely dense star cluster at the center of the galaxy.	
C)	the violent merger of two galaxies in which the collision throws out jets of matter along the rotation axis of the larger galaxy.	
D)	a supermassive black hole at the center of an accretion disk, with material being projected out perpendicular to the disk in both directions.	

14.	I thought black holes gobbled up matter! If the central engine of a double-lobed radio source is a black hole swallowing matter from an accretion disk, where do the jets of matter come from that we see traveling OUTWARD from the galaxy?	
A)	They are accelerated in the ergoregion of the rotating black hole and ejected outward in the black hole's equatorial plane.	
B)	They are composed of material that has been accelerated from two hemispheres toward the black hole with such speed that it escapes again on two opposite sides of the black hole.	
C)	The jets arise in the weak galactic magnetic field, not in the region near the black hole.	
D)	They are squirted out by high pressure in the accretion disk before the matter reaches the black hole.	

15.	Quasars, double radio sources, and BL Lacertae objects may well be the same kind of object, the different appearance of them being simply that	
A)	their position in the universe is different: Quasars are in our Galaxy, double radio sources are associated with other galaxies, and BL Lacertae objects are within the vast voids of space between galaxies.	
B)	the orientation of our line of sight to the axis of their ejected jets of matter is different.	
C)	their ages are different: BL Lacertae objects evolving through the double radio source phase end as quasars.	
D)	their sizes are different: Quasars are star-sized, double radio are sources larger, and BL Lacertae objects are galaxy-sized.	

Answer Key

1.	C	
2.	D	
3.	C	
4.	B	
5.	A	
6.	A	
7.	C	
8.	B	
9.	A	
10.	A	
11.	B	
12.	D	
13.	D	
14.	D	
15.	B