Deck 17: Formation of Structure

Question 1

Which is NOT an ingredient needed to build a cosmological simulation of large-scale structure formation?

A) the spectrum of density fluctuations that quantum mechanics imprints on the early universe
B) the density of dark matter and luminous matter in the universe
C) the grand unified theory
D) the density of dark energy in the universe

Answer 1

the grand unified theory

Question 2

How much of the total mass of the universe is made up of hot dark matter?

A) 5 percent
B) 25 percent
C) 45 percent
D) 90 percent

Answer 2

5 percent

Question 3

Which of the following provided the gravity to form galaxy fragments in the early universe?

A) cold dark matter halos
B) galaxy clusters
C) hot dark matter halos
D) large clouds of gas and dust

Answer 3

cold dark matter halos

Question 4

Why can't dark matter halos collapse to be the same size as the visible parts of galaxies?

A) Dark matter can't dissipate its energy through radiation.
B) Dark matter is mostly made of mini black holes.
C) Dark matter has much more angular momentum.
D) Dark matter annihilates when it begins to get that dense.

Question 5

Which of the following CANNOT be dark matter?

A) axions
B) positrons
C) photinos
D) neutrinos

Question 6

Which of the following structures is the largest?

A) globular cluster
B) galaxy cluster
C) galaxy group
D) supercluster

Question 7

Our Milky Way Galaxy is a member of:

A) the Local Group.
B) the Virgo Cluster.
C) the Virgo Supercluster.
D) all of the above

Question 8

The earliest isotopes of low-mass nuclei (deuterium,helium,lithium,beryllium,boron)were formed in a process called:

A) Big Bang nucleosynthesis.
B) nuclear fission.
C) nuclear fusion.
D) stellar nucleosynthesis.

Question 9

The patterns of walls and voids that are observed:

A) only occur in the Virgo Cluster.
B) are optical illusions.
C) support the cosmological principle.
D) are made of dark matter.

Question 10

Our current ideas on galaxy formation suggest that the visible parts of galaxies:

A) form first and are incorporated into dark matter halos later.
B) form only in the densest parts of dark matter halos.
C) can tell you the total size of the dark matter halo.
D) can tell you everything about the formation history of that galaxy.

Question 11

Galaxy clusters have been observed to be rich in hot,X-ray-emitting gas.What is keeping the gas in the cluster?

A) dark matter
B) the gravitational pull of the galaxies
C) the electromagnetic radiation emitted by the galaxies
D) the low speed of the hot gas

Question 12

What does the large-scale structure of the universe look most like?

A) a sponge with many large holes
B) a loaf of wheat bread with many tiny holes
C) a plate of flat noodles
D) a jar of marbles

Question 13

What is the method used to measure the distances to the farthest galaxies when mapping out large-scale structure?

A) Cepheid variables
B) parallax
C) redshifts and Hubble's law
D) RR Lyrae variables

Question 14

If the quantum fluctuations imprinted on the dark matter halos at the time of the formation of the cosmic microwave background radiation were 10 times larger,galaxies would likely be:

A) smaller.
B) larger.
C) more numerous.
D) nonexistent.

Question 15

What is the importance of the observation that the observed amount of normal matter in the universe matches the amount predicted by Big Bang nucleosynthesis?

A) It shows that dark matter cannot be made up of primarily normal matter, such as protons and neutrons.
B) It shows that dark matter is made up primarily of normal matter, such as protons and neutrons.
C) It shows that there is no need to require dark matter in our understanding of the large-scale structure of the universe.
D) It shows that dark matter is made up primarily of neutrinos.

Question 16

Which of the following makes up a significant amount of hot dark matter?

A) axions
B) neutrinos
C) photinos
D) photons

Question 17

Axions and photinos are examples of:

A) cold dark matter.
B) hot dark matter.
C) neutrinos.
D) normal matter.

Question 18

If neutrinos have mass but do not interact much with normal matter,why can't they be the dominant form of dark matter in the universe?

A) Structure formation would have started with large objects fragmenting into smaller objects.
B) Structure formation would have started with small objects merging to form larger objects.
C) Neutrinos would decay over time and disappear, causing galaxies to fall apart.
D) Neutrinos would not gravitationally lens background galaxies.

Question 19

The observed abundances of helium and deuterium in the universe:

A) support models of Big Bang nucleosynthesis.
B) disprove the Big Bang model of the universe.
C) do not match predictions.
D) contradict the density of matter observed in the universe.

Question 20

What process is most responsible for shaping the large-scale structure of the universe?

A) supernovae from the first generation of stars
B) gravity
C) matter/antimatter annihilation
D) magnetic fields

Question 21

Which of the following statements is correct?

A) Stars evolve.
B) Galaxies evolve.
C) The universe evolves.
D) all of the above

Question 22

Which part of our Milky Way Galaxy has the youngest stars?

A) bulge
B) disk
C) halo
D) cannot measure relative ages of these structures

Question 23

Stars of the first generation were:

A) less massive than today's average star.
B) more massive than today's average star.
C) similar to today's average star.
D) We have no ability to predict.

Question 24

The fact that we do not observe any stars with chemical compositions matching our predictions for the very first generation of stars implies:

A) our ideas of what the first stars were like are incorrect.
B) our technology is not accurate enough to detect the light of the first stars.
C) the first stars died quickly, which implies a high mass.
D) the first stars died quickly, which implies a low mass.

Question 25

We currently live in the universe during its:

A) era of stars.
B) era of degeneracy.
C) era of black holes.
D) era of darkness.

Question 26

We expect the kinds of galaxies that we see at a redshift of 4 (that is,when the universe was much younger)to be:

A) much like what we see today.
B) smaller and much more irregular looking than today.
C) smaller versions of what we see today.
D) far more numerous but with fewer spiral galaxies.

Question 27

Structure formation in our universe:

A) proceeds from the top down.
B) proceeds from the bottom and moves up.
C) begins on all spatial scales at the same time.
D) begins after clusters form.

Question 28

Which era corresponds to the final stage of the universe?

A) Dark Era
B) Degenerate Era
C) Stelliferous Era
D) Primordial Era

Question 29

During which era will the last star form?

A) Dark Era
B) Degenerate Era
C) Stelliferous Era
D) Primordial Era

Question 30

In order from first to last,the specific eras in the universe's history are known as the:

A) Primordial, Stelliferous, Degenerate, and Dark eras.
B) Stelliferous, Black Hole, and Entropy eras.
C) Primordial, Stelliferous, Black Hole, and Entropy eras.
D) Primordial, Stelliferous, Degenerate, Black Hole, and Dark eras.

Question 31

What is one similarity between star formation and galaxy formation?

A) Both processes are dominated by gravity.
B) Both processes are still occurring.
C) Both processes only occurred in the early stages of the universe.
D) Both processes require dark matter.

Question 32

The first galaxies formed:

A) because of merging black holes.
B) from merging clouds of gas.
C) out of large spinning clouds of gas and dust, collapsing under their own gravity.
D) within dark matter halos.

Question 33

We expect the galaxies that we see at a redshift of 4 (that is,when the universe was much younger)will be ________ than galaxies today.

A) more irregular and redder
B) larger and redder
C) smaller and bluer
D) smaller and redder

Question 34

Structure formation in the universe proceeds hierarchically,meaning that:

A) large objects collapse then fragment to form smaller objects.
B) large objects form at the same times as smaller objects.
C) small objects collapse then merge to form larger objects.
D) only small objects form and are stable over time.

Question 35

Galaxies in clusters far from our Milky Way Galaxy appear:

A) much like what we see in nearby clusters.
B) smaller and much more irregular looking than nearby galaxies.
C) smaller versions of what we see in nearby clusters.
D) far more numerous but with fewer spiral galaxies.

Question 36

The first generation of stars most likely formed ________ when the stars died.

A) black holes
B) neutron stars
C) novae
D) white dwarfs

Question 37

During which era will the final black holes decay?

A) Dark Era
B) Black Hole Era
C) Stelliferous Era
D) Primordial Era

Question 38

What do astronomers believe will be the final state of our universe?

A) a "Big Crunch" in which everything collapses back in on itself
B) an ever-expanding universe filled with nothing but hydrogen and helium gas
C) a universe that stops expanding and is filled with nothing but white dwarfs, neutron stars, and black holes
D) an ever-expanding universe filled with photons and elementary particles

Question 39

Which part of our Milky Way Galaxy is the oldest?

A) bulge
B) disk
C) halo
D) Cannot measure relative ages of these structures.

Question 40

What is the evidence that galaxies can merge?

A) Galaxies at higher redshifts are smaller and more irregularly shaped.
B) Hubble Space Telescope has observations of merging galaxies.
C) Simulations show that mergers produce observed galaxy shapes.
D) All of the above.

Question 41

Astronomers currently think that the last stage of the universe will be the Dark Era.Explain what that implies for the future of the universe.

Question 42

The very first generation of stars has never been observed.Explain what this implies about the properties of these stars.

Question 43

Describe the large-scale structure of the universe.

Question 44

What is the observational evidence that gravitational instabilities created the seeds of large-scale structure in the universe?

Question 45

How do astronomers explain the role of mergers in the formation of elliptical galaxies?

Question 46

Put the following eras in the history of the evolution of the universe in their proper order from the earliest to the latest: Black Hole Era,Dark Era,Degenerate Era,Primordial Era,Stelliferous Era.

Question 47

Rank from smallest to largest: galaxy cluster,galaxy group,galaxy supercluster.

Question 48

Describe how elliptical galaxies form.

Question 49

What is the evidence that galaxies form via hierarchical merging?

Question 50

Evaluate some of the difficulties in modeling the evolution of galaxies.