Question 1

Which of the following fills the space between galaxies in a cluster?

Accepted Answer

A)  young blue stars 
B)  old red stars 
C)  hot gas that glows at X-ray wavelengths 
D)  cold, dark gas that only glows in radio wavelengths 
E)  supermassive black holes 
A)  young blue stars 
B)  old red stars 
C)  hot gas that glows at X-ray wavelengths 
D)  cold, dark gas that only glows in radio wavelengths 
E)  supermassive black holes

Question 2

Ignoring the effect of redshift, we expect the galaxies that we see at a redshift of z = 3 will be ________ than galaxies today.

Accepted Answer

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

Question 3

Astronomers estimate distances to large numbers of distant galaxies using

Accepted Answer

A)  the cosmological constant. 
B)  Cepheid variable stars. 
C)  parallax. 
D)  Type II supernovae. 
E)  redshifts. 
A)  the cosmological constant. 
B)  Cepheid variable stars. 
C)  parallax. 
D)  Type II supernovae. 
E)  redshifts.

Question 4

Astronomers can estimate distances to the galaxies in the figure below because of

Accepted Answer

A)  the expansion of the universe. 
B)  our location at the center of the universe. 
C)  dark matter. 
D)  peculiar velocities. 
E)  gravitational redshift. 
A)  the expansion of the universe. 
B)  our location at the center of the universe. 
C)  dark matter. 
D)  peculiar velocities. 
E)  gravitational redshift.

Question 5

In the immediate aftermath of the recombination epoch, neutral hydrogen produced 21-cm photons.What would be the corresponding observed wavelength (at the present epoch) for such photons emitted at redshift z ~ 100?

Accepted Answer

@#LAT-DLM&_observed

Question 6

Structure formation in the universe proceeds hierarchically, meaning that

Accepted Answer

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

Question 7

A galaxy cluster is measured to have a radius of 8 x1019 km, and the small outer galaxies are measured to orbit the cluster center with a circular velocity of 900 km/s.What is the mass of this cluster's core? (Recall that G = 6.67 *10-11 N m2 kg-2.)

Accepted Answer

The equation that we want is M = rv<sup>

Question 8

The Lambda-CDM model combines the properties of ________ to explain the formation of structure in the universe.

Accepted Answer

A)  black holes and neutron stars 
B)  dark energy and cold dark matter 
C)  star formation and angular momentum 
D)  nucleosynthesis and hot dark matter 
E)  gravity and nuclear forces 
A)  black holes and neutron stars 
B)  dark energy and cold dark matter 
C)  star formation and angular momentum 
D)  nucleosynthesis and hot dark matter 
E)  gravity and nuclear forces

Question 9

The James Webb Space Telescope is designed to observe the most distant galaxies in the universe.It will observe them in

Accepted Answer

A)  UV wavelengths. 
B)  IR wavelengths. 
C)  visible wavelengths. 
D)  X-ray wavelengths. 
E)  radio wavelengths. 
A)  UV wavelengths. 
B)  IR wavelengths. 
C)  visible wavelengths. 
D)  X-ray wavelengths. 
E)  radio wavelengths.

Question 10

The peculiar velocity of a galaxy describes its motion relative to the

Accepted Answer

A)  Local Group. 
B)  center of the Milky Way. 
C)  center of the universe. 
D)  Great Attractor. 
E)  cosmic microwave background. 
A)  Local Group. 
B)  center of the Milky Way. 
C)  center of the universe. 
D)  Great Attractor. 
E)  cosmic microwave background.

Question 11

The expansion of the universe will eventually render the CMB invisible because its photons will

Accepted Answer

A)  have wavelengths that will exceed the size of the observable universe. 
B)  be swamped by the light from the ever-increasing star formation rates in the universe. 
C)  not have enough energy to escape the gravity of degenerate stellar remnants. 
D)  all combine and again produce pairs of massive particles. 
E)  not escape the strong gravity of supermassive black holes the size of galaxy clusters. 
A)  have wavelengths that will exceed the size of the observable universe. 
B)  be swamped by the light from the ever-increasing star formation rates in the universe. 
C)  not have enough energy to escape the gravity of degenerate stellar remnants. 
D)  all combine and again produce pairs of massive particles. 
E)  not escape the strong gravity of supermassive black holes the size of galaxy clusters.

Question 12

The Mid-Infrared Instrument (MIRI) that will be attached to the James Webb Space Telescope covers the wavelength range of 5-28 microns.Calculate over what redshift range it can detect the 500 nm photons emitted by galaxies.

Accepted Answer

@#LAT-DLM&_observed = (1 +z)@#LAT-DLM&_emitted

Question 13

The figure below shows a small section of the Virgo Cluster.The indicated galaxy can be classified as

Accepted Answer

A)  elliptical. 
B)  peculiar. 
C)  dwarf. 
D)  ultrafaint. 
E)  quasar. 
A)  elliptical. 
B)  peculiar. 
C)  dwarf. 
D)  ultrafaint. 
E)  quasar.

Question 14

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

Accepted Answer

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 
E)  a pizza with evenly distributed pepperoni 
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 
E)  a pizza with evenly distributed pepperoni

Question 15

Which of the following is a way in which astronomers detect dark matter in clusters of galaxies?

Accepted Answer

A)  by determining the amount of mass necessary to gravitationally lens images of distant objects 
B)  by directly measuring the dark matter using infrared light 
C)  by measuring the peculiar velocity of the galaxy cluster 
D)  by determining the amount of mass necessary to gravitationally collapse clouds of gas to form the number of stars present 
E)  None of these; dark matter cannot be detected in any way. 
A)  by determining the amount of mass necessary to gravitationally lens images of distant objects 
B)  by directly measuring the dark matter using infrared light 
C)  by measuring the peculiar velocity of the galaxy cluster 
D)  by determining the amount of mass necessary to gravitationally collapse clouds of gas to form the number of stars present 
E)  None of these; dark matter cannot be detected in any way.

Question 16

What are the "Dark Ages" in cosmology?

Accepted Answer

After recombination,gas throughout the u

Question 17

Explain how scientists have determined that only ~5 percent of mass and energy in the universe is "ordinary" or "normal" matter.

Accepted Answer

Astronomers detect the presence of dark

Question 18

In studying galaxies of various morphological types, scientists have estimated equivalent mass-to-light ratios (M/L) of about 1-30 in solar units (1 MSUN/1 LSUN), with ratios being lower for spiral galaxies and higher for elliptical galaxies.In galaxy clusters, however, the typical total mass-to-light ratio is estimated in the range 300-600 (MSUN/LSUN).What is the implication of these numbers?

Accepted Answer

The much higher M/L ratio for galaxy clu

Question 19

The Virgo Cluster is at an estimated distance of 16.5 Mpc.What is the average recession speed of the cluster, assuming a Hubble constant of 70km/s/Mpc?

Accepted Answer

A)  1,200 km/s 
B)  32,000 km/s 
C)  300 km/s 
D)  10,000 km/s 
E)  3,800 km/s 
A)  1,200 km/s 
B)  32,000 km/s 
C)  300 km/s 
D)  10,000 km/s 
E)  3,800 km/s

Question 20

The most common type of galaxy found in a galaxy cluster is a ________ galaxy.

Accepted Answer

A)  spiral 
B)  giant elliptical 
C)  giant irregular 
D)  dwarf 
E)  barred spiral 
A)  spiral 
B)  giant elliptical 
C)  giant irregular 
D)  dwarf 
E)  barred spiral

Exam 23: Large-Scale Structure in the Universe

Which of the following fills the space between galaxies in a cluster?

Ignoring the effect of redshift, we expect the galaxies that we see at a redshift of z = 3 will be ________ than galaxies today.

Astronomers estimate distances to large numbers of distant galaxies using

Astronomers can estimate distances to the galaxies in the figure below because of

In the immediate aftermath of the recombination epoch, neutral hydrogen produced 21-cm photons.What would be the corresponding observed wavelength (at the present epoch) for such photons emitted at redshift z ~ 100?

Structure formation in the universe proceeds hierarchically, meaning that

A galaxy cluster is measured to have a radius of 8 x1019 km, and the small outer galaxies are measured to orbit the cluster center with a circular velocity of 900 km/s.What is the mass of this cluster's core? (Recall that G = 6.67 *10-11 N m2 kg-2.)

The Lambda-CDM model combines the properties of ________ to explain the formation of structure in the universe.

The James Webb Space Telescope is designed to observe the most distant galaxies in the universe.It will observe them in

The peculiar velocity of a galaxy describes its motion relative to the

The expansion of the universe will eventually render the CMB invisible because its photons will

The Mid-Infrared Instrument (MIRI) that will be attached to the James Webb Space Telescope covers the wavelength range of 5-28 microns.Calculate over what redshift range it can detect the 500 nm photons emitted by galaxies.

The figure below shows a small section of the Virgo Cluster.The indicated galaxy can be classified as

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

Which of the following is a way in which astronomers detect dark matter in clusters of galaxies?

What are the "Dark Ages" in cosmology?

Explain how scientists have determined that only ~5 percent of mass and energy in the universe is "ordinary" or "normal" matter.

The Virgo Cluster is at an estimated distance of 16.5 Mpc.What is the average recession speed of the cluster, assuming a Hubble constant of 70km/s/Mpc?

The most common type of galaxy found in a galaxy cluster is a ________ galaxy.

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Formation of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Planetary Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

The Interstellar Medium and Star Formation

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Milky Waya Normal Spiral Galaxy

The Expanding Universe

Cosmology

Life

Filters

A galaxy cluster is measured to have a radius of 8 x10¹⁹ km, and the small outer galaxies are measured to orbit the cluster center with a circular velocity of 900 km/s.What is the mass of this cluster's core? (Recall that G = 6.67 *10^-11 N m² kg^-2.)