Deck 25: Galaxies and Dark Matter: The Large-Scale Structure of the Cosmos

Question 1

Dark matter does not affect galaxy collisions.

Answer 1

False

Question 2

The younger the universe was, the more abundant quasars were, according to our deepsurveys.

Answer 2

True

Question 3

Collisions between galaxies have little effect on the individual stars.

Answer 3

True

Question 4

The Lyman-alpha "forest" are absorption lines in a quasar spectrum created by all of thegases along the billions of light-years its energy has traversed.

Question 5

Galaxies contain at most one supermassive black hole.

Question 6

On average, the stars in elliptical galaxies are older than the stars in spiral galaxies.

Question 7

When observing a very distant quasar, we are actually seeing the universe the way it waswhen it was much younger than it is today.

Question 8

While yet unseen, some gravitational evidence suggests the existence of dark galaxies.

Question 9

Giant irregulars are the most massive of all known galaxies.

Question 10

The last quasar probably died out a billion years ago, for none lie within a billion light-yearsof us.

Question 11

Distant galaxies tend to be much bluer than those nearby.

Question 12

On average, elliptical galaxies are much older than large spiral galaxies.

Question 13

Galaxies in clusters are much more likely to become "active" than ones alone in space.

Question 14

Vast majority of the known volume of the universe lies in the voids.

Question 15

A large cluster's mass can be over a thousand times that of our Galaxy.

Question 16

Most large spirals and ellipticals are comparable to the Milky Way in mass.

Question 17

While quasars may have now vanished, the large black holes they formed are still around,just not being fed as well any more.

Question 18

Spiral galaxies are much more common in the centers of rich clusters than in the universe asa whole.

Question 19

For nearby spirals, their rotation curves help measure both light and dark matter.

Question 20

It is now believed the majority of mass for most galaxies lies in their dark halos.

Question 21

Due to the galaxy density and collisions, ________ are rare in the centers of clusters.

A)irregulars
B)quasars
C)spirals
D)black holes
E)blazars

Question 22

The largest voids may span 300 million light-years across.

Question 23

Based on galactic rotation curves and cluster dynamics, we think dark matter:

A)is a minor component of the entire mass of the universe.
B)is best detected from the X-rays it produces in the intergalactic medium.
C)will have no effect on the fate of the universe.
D)comprises over 90% of the entire mass of the universe.
E)will doom the universe to collapse, overcoming the redshifts we now observe.

Question 24

Gravity lensing lets us map the distribution of both visible and dark matter.

Question 25

The distance between adjacent galaxies in a typical cluster is about ________ times the sizeof a typical galaxy.

A)two or three
B)five or less
C)ten to twenty
D)a hundred
E)a thousand

Question 26

As we look at larger and larger scales in the universe, we find:

A)smaller and smaller masses.
B)almost exclusively visible matter.
C)a larger and larger percentage of the matter is visible.
D)a larger and larger percentage of the matter is dark.
E)an equal amount of visible and dark matter.

Question 27

How massive are the largest known galaxies?

A)a few million solar masses
B)a hundred million solar masses
C)a few billion solar masses
D)a trillion solar masses
E)hundreds of trillions of solar masses

Question 28

The type of galaxy where we can track its motion through the intergalactic medium is a:

A)blazar.
B)quasar.
C)pulsar.
D)Head-Tail Radio Galaxy.
E)Seyfert galaxy.

Question 29

The pregalactic blobs had masses similar to:

A)the Earth.
B)the Sun.
C)globular clusters.
D)the Large Magellanic Cloud.
E)the Milky Way.

Question 30

Collisions between galaxies are thought to:

A)have stopped about 5 billion years ago.
B)be commonplace.
C)have never occurred.
D)be extremely rare.
E)have only occurred between 10 and 15 billion years ago.

Question 31

Rotation curves for spiral galaxies show:

A)they are slowing down.
B)rotation speed drops off further from the nucleus.
C)most have dark halos.
D)most of the mass lies in the nucleus.
E)no relation to mass.

Question 32

What is true of spiral galaxies?

A)They are much less common at larger redshifts.
B)They are relatively rare in regions of high galaxy density.
C)They are only found in the center of rich galaxy clusters.
D)They have never been seen to have large redshifts.
E)They evolve from giant ellipticals.

Question 33

When spiral galaxies do collide, the impact is greatest on their:

A)individual stars.
B)galactic nuclei.
C)giant molecular clouds.
D)open clusters.
E)globular clusters.

Question 34

According to the HST data, very distant (and early)galaxies tend to be:

A)larger and bluer that modern galaxies.
B)nothing but quasars.
C)smaller, bluer, and more irregular than modern ones.
D)redder, due to the recession of the universe.
E)very well formed into clusters of nothing but spirals.

Question 35

Collisions between galaxies:

A)are much rarer than collisions between stars.
B)can turn elliptical galaxies into spirals.
C)cause large numbers of stars to collide and explode.
D)cause the gas and dust clouds to collide, leading to rapid star formation.
E)are the best explanation for gamma-ray burst events.

Question 36

Why are supermassive galaxies often found at the cores of rich galaxy clusters?

A)Most of the matter forming the cluster fell into the center to form one large galaxy.
B)They are the result of many galactic mergers; one galaxy growing at the expense of others.
C)Such a large galaxy attracted smaller galaxies around it to form a cluster.
D)Large galaxies, passing a cluster, get captured into the center.
E)Many globular clusters swarmed together to form it.

Question 37

Which of these is NOT considered a fine example of galactic collisions?

A)the Cartwheel Galaxy
B)the Antennae Galaxies
C)the Whirlpool Galaxy
D)M-31 in Andromeda
E)M-87 in Virgo

Question 38

According to their rotation curves, most spiral galaxies:

A)rotate as a solid body.
B)rotate counterclockwise.
C)have decreasing rotational speeds with increasing distance.
D)contain dark matter.
E)contain dark energy.

Question 39

A radio galaxy whose lobes are swept back as if forming a tail probably indicates that:

A)this is evidence for intergalactic matter.
B)the galaxy is about to evolve into a spiral.
C)the galaxy is isolated, not part of a cluster.
D)the galaxy is moving towards Earth.
E)there must be another galaxy nearby.

Question 40

Compared to the Milky Way, how many stars are contained in the most massive galaxies?

A)two to three times as many
B)tens of times as many
C)hundreds of times as many
D)thousands of times as many
E)millions of times as many

Question 41

Astronomers think most galaxy interactions took place at redshifts of greater than 1 because:

A)stars were bigger.
B)galaxies were bigger.
C)galaxies were smaller.
D)clusters were more diffuse.
E)clusters were more compact.

Question 42

The peak of the quasar epoch was:

A)when there was still enough dark matter to fuel the supermassive black holes in their bar.
B)when there was still sufficient mass to fuel the supermassive black holes at their center.
C)before the formation of galaxies.
D)before the star formation epoch.
E)before mass had a chance to accumulate at the nucleus.

Question 43

Gravitational lensing of distant, faint irregular galaxies may be the key to:

A)mapping the dark matter.
B)quasar energy production.
C)understanding galactic rotation curves.
D)understanding active galactic nuclei.
E)determining galactic redshifts.

Question 44

What evidence has Chandra found to contradict the hypothesis that black holes merge duringgalaxy collisions?

A)a double black hole in a single galaxy
B)a black hole without a host galaxy
C)a hypermassive black hole
D)a triple black hole system
E)a dwarf galaxy containing a black hole

Question 45

The further away a galaxy is:

A)the older it is.
B)the further ahead in the future it will exist.
C)the longer ago it existed.
D)the larger it appears.
E)the more massive it is.

Question 46

Active galaxies are having their central engines temporarily fed by what occurrence?

A)a sudden surge in star formation in the nucleus
B)a series of supernovae all occurring in the dense nuclear bulge
C)a close interaction with a neighboring galaxy
D)attack by a swarm of globular clusters
E)the merger of a binary black hole system

Question 47

________ galaxies may bridge the gap between spiral galaxies and quasars.

A)Hickson
B)Arp
C)Core-halo
D)Seyfert
E)Hubble

Question 48

Why is it thought that quasars probably spend only a fairly short time in their highlyluminous phase?

A)because there aren't many quasars around today
B)because there aren't any quasars closer than about a redshift of 1
C)because all quasars are at about the same epoch, narrowly defined in time
D)because a black hole could not power a highly luminous quasar for more than a few millionyears
E)because quasars are known to be the consumers of massive galaxies

Question 49

Redshift surveys give us:

A)an idea of how turbulent the intergalactic gas is.
B)a 3-D layout of galaxies in space.
C)the total mass of the universe.
D)a more accurate census of the Local Group.
E)a better value of the speed of light.

Question 50

An interaction between a large and a small elliptical galaxy that results in a large spiral and asmall elliptical galaxy takes:

A)several thousand years.
B)several hundred thousand years.
C)several million years.
D)several hundred million years.
E)several billion years.

Question 51

A galaxy that was once a quasar is likely to:

A)have burned all its fuel by now and be dark.
B)now be a dwarf irregular.
C)have a black hole at its nucleus.
D)still be a quasar.
E)be less than 5 billion years old.

Question 52

The type of radio galaxy that reveals its motion through the intergalactic medium is called a:

A)quasar.
B)dual lobe.
C)bipolar jet.
D)head-tail.
E)Seyfert.

Question 53

A billion solar mass black hole has a radius of only:

A)one solar diameter.
B)20 A.U.
C)400 A.U.
D)3 parsecs.
E)20 parsecs.

Question 54

Star streams that are seen around the Milky Way Galaxy are probably the result of:

A)stars ejected from the Galaxy by gravitational encounters with the central black hole.
B)tidal interactions with satellite galaxies.
C)a collision with a large galaxy in the distant past.
D)stars being pulled from the Andromeda Galaxy.
E)spiral density waves.

Question 55

In its most energetic phase, a quasar can probably only last:

A)a few days.
B)a few years.
C)a few thousand years.
D)a few million years.
E)a few billion years.

Question 56

A merger between two large galaxies of comparable size will most likely produce:

A)two small elliptical galaxies.
B)a large elliptical galaxy.
C)a small elliptical galaxy and a small spiral galaxy.
D)a large spiral galaxy.
E)a small elliptical galaxy and a large spiral galaxy.

Question 57

Some quasars show absorption spectra with a smaller redshift than their emission spectra;this indicates that:

A)we still don't understand redshifts.
B)they are much closer than previously thought.
C)there is cooler gas between us and the quasar.
D)their black holes are still contracting.
E)their black holes are still expanding.

Question 58

What is true of spiral galaxies?

A)They are much less common at larger redshifts.
B)They are relatively rare in regions of high galaxy density.
C)They are only found in the center of rich galaxy clusters.
D)They have never been seen to have large redshifts.
E)They evolve from giant ellipticals.

Question 59

A red supergiant is observed in a globular cluster in another galaxy (located 150,000 light-years away). It is predicted, based on its mass and age of the star, that it will supernova in about10,000 years. When will this supernova be visible on Earth?

A)10,000 years from now
B)10,000 years ago
C)150,000 years from now
D)150,000 years ago
E)160,000 years from now

Question 60

A merger between a small elliptical galaxy and a large spiral galaxy will most likely resultin:

A)a large elliptical.
B)a large spiral.
C)a small elliptical and a large elliptical.
D)a small elliptical and a large spiral.
E)a small spiral and a large elliptical.

Question 61

Voids contain about what percentage of the universe's mass?

A)0
B)5-10
C)40-50
D)100
E)cannot be determined

Question 62

A supernova that occurs 10,000 years from now in a galaxy 50,000 light-years away:

A)will be observed on Earth 10,000 years from now.
B)was observed on Earth 40,000 years ago.
C)will be observed on Earth 40,000 years from now.
D)was observed on Earth 50,000 years ago.
E)will be observed on Earth 50,0000 years from now.

Question 63

Gas that has never been cycled through a galaxy or a star is said to be ________.

Question 64

From studies of the masses of individual galaxies and the masses of clusters of galaxies, it isnow apparent that up to ________ of the universe is composed of dark matter.

Question 65

The quasars with the largest presently known redshifts are close to:

A).96.
B)3.
C)6.
D)10.
E)65.

Question 66

In a collision between clusters of galaxies, what happens to the hot gas and dark matter,based on observations of the "bullet cluster"?

A)The gas stays with the luminous matter, but the dark matter moves on.
B)The dark matter stays with the luminous matter, but the gas moves on.
C)Both the dark matter and gas continue their motion, leaving behind the luminous portions ofthe galaxies.
D)The luminous matter moves on, leaving behind the dark matter and gas.
E)The dark matter moves with the luminous matter, leaving behind the gas.

Question 67

Data on binary galaxies is analyzed to determine their average masses under the assumptionthat they, like binary stars, have ________ orbits.

Question 68

Giant elliptical galaxies may be the result of ________ in the centers of rich clusters.

Question 69

A red supergiant is observed in a globular cluster in another galaxy (located 150,000 light-years away). It is predicted, based on its mass and age of the star, that it will supernova in about10,000 years. Is this star still there?

A)No, it died in a supernova 10,000 years ago.
B)No, it died in a supernova 140,000 years ago.
C)No, it died in a supernova 150,000 years ago.
D)Yes, it will die in a supernova in 10,000 years.
E)Yes, it will die in a supernova 160,000 years from now.

Question 70

Supermassive elliptical galaxies have been seen to have how many supermassive black holesin or near their center?

A)none
B)always one
C)at least one; no more than a few
D)dozens
E)hundreds

Question 71

All of the following are clusters of galaxies EXCEPT:

A)Andromeda.
B)Perseus.
C)Coma.
D)Virgo.
E)Hydra.

Question 72

A galaxy is at a distance of one billion light-years. Which of the following is true?

A)We see the galaxy the way it will be in one billion years.
B)We see the galaxy the way it was one billion years ago.
C)We see the galaxy the way it was when the universe was one billion years old.
D)We see what our galaxy will be like in one billion years.
E)We have no knowledge of anything at that distance.

Question 73

What is the Great Wall?

A)It is a ridge on the Moon near the crater Birt.
B)It is the distance beyond which astronomers cannot view any more galaxies or even quasars.
C)It is a large sheet of galaxies measuring 70 Mpc by 200 Mpc.
D)It is the time before the universe started expanding, about which we can never know anything.
E)It is an enormous intergalactic cloud of dust and gas that hides more distant galaxies.

Question 74

The Sloan Digital Sky Survey uses:

A)a single space-based telescope.
B)a single Earth-based telescope.
C)an array of Earth-based telescopes.
D)several widely distributed Earth-based telescopes.
E)several space-based telescopes.

Question 75

When two galaxies move very closely to each other, their ________ may dramaticallyrearrange their visible structures.

Question 76

Careful observations of nearby normal and active galaxies reveal that the mass of the centralblack hole is well correlated with the mass of the galactic bulge. The ratio of bulge mass to blackhole mass is roughly:

A)1 to 2000.
B)1 to 200.
C)1 to 20.
D)20 to 1.
E)200 to 1.

Question 77

Infall of ________ may explain the higher than expected star formation rates in galaxies.

Question 78

The lensing of a distant quasar is produced by ________ of a foreground galaxy.

A)all the normal matter and dark matter
B)only the mass of the black hole in the nucleus
C)an individual star
D)a pulsar's intense magnetic field
E)a relativistic jet

Question 79

The energy radiated from a typical quasar requires that its black hole accrete about:

A)1 solar mass per 100 years.
B)1 solar mass per 10,000 years.
C)1 Jupiter mass per year.
D)10 solar masses per year.
E)1,000 solar masses per year.

Question 80

If the merger theory is correct, the brightest active galactic nuclei should:

A)be in the smallest elliptical galaxies.
B)contain the youngest stars.
C)contain the least mass.
D)contain supermassive black holes.
E)form small irregular galaxies.