A) very powerful and compact sources of energy at the centers of distant galaxies
B) projectiles shot out of our own Galaxy and moving out into intergalactic space
C) energetic collisions of comets in the Oort Cloud
D) anti-matter stars in the halo of the Milky Way Galaxy
E) a completely baffling mystery with no hint of an answer
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A
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A) strong radio emission showing regular pulses
B) no lines in the spectrum at all
C) redshifts that indicate they are far away
D) tremendous proper motion (apparent motion across the sky)
E) gravitational lenses clearly visible around them
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A) there are more quasars closer to us than farther away
B) the largest number of quasars can be found at about a distance of 1 million LY away from us
C) the number of quasars is pretty much the same at every range of distances (as many are close to us as far away)
D) the largest number of quasars were found exactly at the time of the big bang (when the universe began) ; quasars have been declining steadily in numbers ever since
E) the largest number of quasars can be seen at about the distance corresponding to a time when the universe was only 20% its current age (a time when the universe was still young)
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A) the jets are "spit out" from the chaotic accretion disks of supermassive black holes in directions that are perpendicular to the disk
B) the jets are produced when a whole series of massive stars near the galaxy's center explode at the same time as supernovae
C) the jets are connected with the dark matter in distant galaxies; this dark matter is in two large bubbles above and below the galaxy
D) the jets are a kind of astronomical mirage, produced by gravitational lensing by a large mass between us and the quasar
E) there is no current explanation for these jets; they are an unsolved mystery
Section 27.3: Quasars as Probes of Evolution in the Universe
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A) all the clusters of stars are at the outer edges of galaxies; we have never seen any clusters of stars toward the middle of galaxies
B) things at the centers of galaxies all move so fast, the stars in the cluster would be launched outward and would never remain at the center
C) to fit as much matter into the cluster as we observe, the stars in the cluster must be so close to each other they would merge into a superstar and soon collapse into a black hole
D) we could easily observe such a star cluster in distant galaxies, and we don't see them
E) none of the above
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C
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A) radio
B) infrared
C) ultraviolet
D) microwaves
E) gamma-ray
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A) there were very few quasars long ago, and their numbers have been growing since
B) quasars began emerging only about a billion years ago, and now there are many more than ever
C) quasars have been around since the big bang, but the radiation they give off gets stronger and stronger as time in the universe goes on
D) the number of quasars reached a maximum some time ago, and now the numbers have been declining
E) quasars actually don't demonstrate any evolution; the number of quasars has been pretty constant for the entire history of the universe
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A) quasars have been discovered in more than one direction in space
B) quasars appear to be small in angular extent (they look like points)
C) quasars vary in brightness with time
D) relatively nearby quasars show "fuzz" around them with the same spectra and redshift as the quasar
E) you can't fool me; there is no evidence whatsoever that quasars are connected with galaxies
Section 27.2: Supermassive Black Holes: What Quasars Really Are
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A) the understanding that most stars become white dwarfs when they die and white dwarfs are much smaller than main-sequence stars
B) the discovery that the Milky Way Galaxy has a black hole at the center with enough mass for 4 million Suns
C) the discovery that the galaxies mostly show a red shift
D) the discovery of exoplanets (planets orbiting other stars) throughout the Galaxy
E) the discovery of Herbig-Haro objects around newly forming stars
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A) in the centers of nearby galaxies
B) in the constellation of Sagittarius, the direction where we see the center of the Milky Way
C) right next to 3C273, the first quasar that was understood
D) in or near a distant cluster of galaxies that can act like a gravitational lens
E) there is simply no way that she can improve her chances of finding such a quasar; such discoveries are completely random
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D
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A) quasars are seen when the supermassive black hole at the center of a galaxy has a lot of "food to eat" (stars and gas) and the amount of available food tends to decrease with time
B) quasars are supermassive black holes at the centers of galaxies, and such black holes are constantly losing mass and thus getting less and less able to pull on anything
C) quasars tend to merge all the time, and so there are fewer and fewer of them as time goes on
D) quasars are caused by many supernovae going off at the same time, and massive stars only exploded in the early history of the universe; they don't explode today
E) no one has the slightest idea on how to answer this question; it is completely unsolved
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A) quasars can be seen in front of galaxies, but they have nothing to do with them
B) quasars can only be seen behind galaxies, but they have nothing to do with them
C) quasars and galaxies are never seen together and they have nothing to do with each other
D) quasars are active supermassive black holes at the centers of galaxies
E) quasars are a complete mystery; so it is not possible to say how they might be related to galaxies
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A) parallax
B) Cepheid variables
C) measuring the size of its dark matter halo
D) finding the red?shift and using Hubble's Law
E) the turnoff point of the main sequence on an H-R diagram
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A) new stars can form in the accretion disk just before they are pulled into the black hole
B) new stars can form when the flow of particles from a black hole accretion disk or jet compresses the material some distance away from the black hole and starts the "clumping" that leads to the formation of stars
C) such supermassive black holes often explode and their huge explosion can force the forming of new stars
D) after billions of years, when black holes no longer have an active accretion disk, they can turn into a cluster of new stars
E) so much material comes out of the event horizon of supermassive black holes, there is more than enough new material for generations of stars
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A) like the Sun
B) like the combined luminosity of a cluster of a hundred stars
C) much fainter than the Sun
D) like the accretion disk of a black hole formed from a single star (like Cygnus X-1)
E) like the combined luminosity of a hundred trillion (1014) Suns
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A) antimatter and matter colliding at the center of a galaxy
B) chain reactions of supernova explosions
C) matter falling toward a supermassive black hole at the center of a galaxy
D) the left-over (and stored) energy of the big bang explosion
E) you can't fool me; astronomers have no explanation for what the energy source is for the quasars -- they are completely baffled
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A) the discovery of a gravitational lens in M87
B) the discovery that the distribution of stars in the galaxy becomes densely concentrated at the center (much more so than in normal elliptical galaxies)
C) the discovery of an inner disk of rapidly swirling gas in the center of the galaxy
D) the Doppler shifts measured for spectral lines coming from rapidly moving gas
E) evidence that M87 may have grown to be a giant elliptical through collisions with other, smaller galaxies, some of whose material may have fallen into M87's center
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A) the galaxy was formed recently, and is just now going through its "adolescence"
B) the galaxy must have an enormous Doppler shift and must have traveled here from a large distance away
C) the galaxy must be made entirely of very massive stars; very few low mass stars exist in it
D) the galaxy must be undergoing a collision with another galaxy that is providing fresh fuel for its central black hole
E) the dark matter in the galaxy must be undergoing a transformation into matter we can see
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A) from the outer spiral arms of the galaxy in which the quasar is located
B) from inside the event horizon of a supermassive black hole
C) from supernova explosions (a whole bunch of them all at once) in the galaxy in which the quasar is located
D) from an accretion disk around a supermassive black hole
E) from a much more distant object that happens to lie behind the quasar and fools us into thinking the quasar is shining
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A) observe one quasar at all wavelengths of the electromagnetic spectrum
B) find a number of cases where a quasar seen in a cluster of galaxies has the same redshift as all the galaxies in the cluster
C) find a number of quasars that seem associated with a galaxy that has a different redshift from the quasar
D) measure carefully how long the quasar takes to undergo regular changes in its light output
E) demonstrate by observing many quasars that brighter-looking quasars have higher redshifts
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