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17-17 > 17-18 > Flashcards

17-18 Flashcards

1
Q

Seyfert galaxies appear similar to normal spirals with extremely luminous cores

A

True

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2
Q

The broad emission lines of Seyfert galaxies imply high gas speeds in the nucleus.

A

True

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3
Q

The luminosity of a Seyfert galaxy varies with a regular period of months or years

A

false

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4
Q

Seyfert galaxies rarely show evidence of collisions with other galaxies

A

false

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5
Q

Double-lobed radio galaxies are an effect of black hole jets

A

True

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6
Q

Quasars are radio sources that look like stars in visible-light photograph

A

True

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7
Q

Quasars are isolated supermassive black holes, and not associated with galaxies.

A

false

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8
Q

Supermassive black holes are very large, the most massive even larger than our Solar System.

A

false

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9
Q

The structure of black hole jets is believed to be controlled by magnetism

A

True

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10
Q

Matter flowing into a black hole cools until it is accelerated into a jet

A

false

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11
Q

The unified model of active galactic nuclei focuses on differences caused by the age of the central
black hole.

A

false

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12
Q

Most supermassive black holes are dormant

A

True

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13
Q

Black holes erupt when matter flows into their accretion disk

A

True

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14
Q

The size of a galaxy’s central black hole is proportional to the mass of its disk

A

false

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15
Q

Quasars are caused by galaxy collisions in the early Universe

A

true

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16
Q

Collisions in the early Universe were rare.

A

false

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17
Q

Normal galaxies in the present never went through an active galaxy phase

A

false

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18
Q

Supermassive have weaker gravity than stellar-mass black holes, producing slower spins for the
infalling matter

A

false

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19
Q

Active galactic nuclei were first found through observations in the ____ wavelength band

A

radio

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20
Q

Seyfert galaxies are ___

A

spiral galaxies

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21
Q

Double-lobed radio galaxies are ____.

A

elliptical galaxies

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22
Q

Quasars are ____

A

extremely luminous

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23
Q

What is the best description of Hanny’s Voorwerp

A

glowing green

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24
Q

The energy output of a Seyfert galaxy ____

A

hundred times the luminosity of the milky way

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25
Q

The high luminosity of a Seyfert galaxy is concentrated in a ____

A

small area

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26
Q

Seyfert galaxies are always ____ galaxies

A

spiral

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27
Q

What produces the lobes in double-lobed radio galaxies ____ _____ jets

A

black hole

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28
Q

A supermassive black hole that is erupting may push ____ disk

A

acceration

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29
Q

When they were first discovered, quasars appeared to be ____.

A

small star objects

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30
Q

Quasars have a(n) ____.

A

extremely high redshift

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31
Q

Gas falling into a black hole becomes ____ due to an increase of speed

A

hot

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32
Q

Matter falling into a black hole arranges itself in the shape of a ____

A

disk that is thick

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33
Q

The motion of gas in accretion disks and jets is ____

A

poorly understood but may relate to magnetism

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34
Q

A unified model of active galaxy cores can explain different types of Seyfert galaxies, quasars and
other active galaxy types by differences in the ____

A

tilt of the accertration disk

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35
Q

A supermassive black hole erupts when ____.

A

a sudden flood of matter flows inward

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36
Q

Supermassive black holes erupt in central ____.

A

bulges

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37
Q

Many galaxies with erupting black holes are found in one pair of orbiting ____

A

galaxies

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38
Q

The formation process for supermassive black holes is linked with the formation of galactic central ____.

A

bulges

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39
Q

The formation of a galactic central bulge is believed to ____.

A

To be a violent process

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40
Q

Quasars are common in the early Universe because ____ at that time

A

galatic collisions were more frequent

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41
Q

Quasars ____

A

are an early stage of the formation of common

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42
Q

A galaxy’s supermassive black hole represents about ____ for elliptical galaxies

A

Half a percent of the mass of the central bulge

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43
Q

In the unified model, an accretion disk viewed from the side will cause narrow ____ lines to be present in the
spectrum of a Seyfert galaxy

A

spectral

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44
Q

Astronomers conclude that quasars must come from the earliest phases of the Universe because they have a large ____ spectra

A

redshifted

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45
Q

Active galaxies are believed to be the product of collisions and interactions because of the transfer of ___

A

mattter

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46
Q

The accompanying graph shows that quasars formed starting the formation of the ____

A

universe

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47
Q

Most quasars have a redshift between ____ and ____

A

2 -3

48
Q

Active galaxies were first discovered by observations in the _______________ wavelength band

A

radio

49
Q

A spiral galaxy with an extremely luminous, active core is called a(n) _______________ galaxy

A

seyfart

50
Q

Some active radio galaxies exhibit _____ of gas heated by jet

A

lobes

51
Q

Matter falling into a black hole forms a(n) _______________ disk

A

acceration

52
Q

Black hole jets are believed to be focused and confined by the enclosing magnetic _____

A

tubes

53
Q

The Doppler effect in the spectra of quasars show very high _______________

A

redshifts

54
Q

Ultra luminous radio sources associated with small visible-light objects are called ______.

A

quesars

55
Q

Matter falling into a black hole converts ________ energy into thermal energy.

A

Gravitational

56
Q

Active galaxies are the result of galactic _______________

A

collisions

57
Q

Olber’s paradox is explained by the fact that the Universe is neither static nor infinite in age.

A

true

58
Q

The “big bang” was an explosion of material that created galaxies flying away from the center of the
explosion.

A

false

59
Q

Cosmologists cannot begin their history of the big bang at a time of exactly zero because it cannot be
explained by current physics

A

True

60
Q

The big bang happened everywhere in the Universe at the same time

A

true

61
Q

Tiny amounts of lithium and beryllium were formed in the big bang

A

false

62
Q

When matter and antimatter particles combine, the two particles annihilate each other and convert their
mass into energy in the form of two gamma rays.

A

True

63
Q

After nuclear reactions in the big bang had ended, about 25% of the mass of the Universe was in the
form of helium nuclei

A

True

64
Q

The Universe is isotropic, but not homogenous

A

False

65
Q

The cosmological principle states that any observer in any galaxy sees the same general properties for
the Universe.

A

True

66
Q

The cosmological redshifts of galaxies are Doppler shifts

A

True

67
Q

All dark matter in our Universe falls into the category of “hot dark matter”

A

False

68
Q

Normal matter is baryonic

A

True

69
Q

The expansion of the Universe is acceleratin

A

True

70
Q

In the early universe, the electromagnetic and strong nuclear forces were joined together to make the
electrostrong force

A

False

71
Q

Dark energy accounts for about 70% of the critical density of the Universe.

A

True

72
Q

The decoupling of the strong force from the electroweak force provided energy for a rapid inflation of
the Universe.

A

True

73
Q

Olber’s paradox states that the sky should ____.

A

as bright but its not

74
Q

The Universe has ____.

A

Has no edge nor center

75
Q

The proper interpretation of the Hubble law (which relates the redshift of a galaxy to its distance) is
that as time goes on, galaxies are staying relatively ____ in space. While the space between the galaxies ____

A

still
expands

76
Q

The Hubble time is the age ____.

A

of the universe

77
Q

Hot gas created during the big bang should be detectable because the ____.occurred everywhere at once and should be visible in _____ at long look-back in time

A

big bang —- any direction at long
look-back time

78
Q

Arno Penzias and Robert Wilson are famous for ____

A

detecting the large redshift background radiation from the big bang

79
Q

The microwave emission detected by Arno Penzias and Robert Wilson fits a blackbody spectrum with
a temperature of about ____ K

A

2.7

80
Q

Penzias and Wilson detected microwave radiation because the big bang created longer ____ energy that has been redshifted by expansion

A

wavelength

81
Q

In the very first phase after the big bang, when the Universe was about a microsecond old, space was
filled with high energy ____.

A

protons

82
Q

During one phase of the big bang, gamma ray photons were creating electrons and positrons
(anti-electrons). At this time, the Universe also contained ____ and ____

A

Protons and neutrons

83
Q

Einstein’s mass-energy equivalence ( ) is important to the first phases of the big bang in ____ rays photons create matter and _____

A

. gamma ray ——— antimatter

84
Q

The big bang only created hydrogen and helium (with miniscule amounts of lithium) because elements with an atomic weight of ____or ___ are unstable

A

5 or 8

85
Q

The cosmic microwave background radiation was emitted during a time when ____ was the important
process in the Universe

A

Recomination

86
Q

Figure 18-12 (for questions 14-17)
14. One year after the big bang, the temperature of the Universe was approximately ____ ^6 degrees Kelvin

A

10^6

87
Q

The Universe had a temperature of a few hundred million degrees K at approximately ____ after the
big bang.

A

one hour

88
Q

The re-ionization of the Universe occurred closest to ____ of degrees Kelvin.

A

tens

89
Q

The change from a radiation-dominated to a matter-dominated Universe occurred at a temperature
closest to ____ of degrees Kelvin.

A

Tens of thousands

90
Q

The proper interpretation of a what a galaxy’s redshift measures is the stretching of space between the ____ and the _____

A

galaxy and the observer

91
Q

Modern observations have shown that the geometry of the Universe is ____ and universe must be _____

A

flat —— infinite

92
Q

The main criterion for deciding between Universe geometries is ____.

A

density

93
Q

Which statement about the behavior of Universe geometries is correct?
Closed universes ____ and then ____

A

expand and then contract

94
Q

Ordinary matter makes up approximately ____ percent of the critical density of the Universe

A

4.5

95
Q

Clusters of galaxies are distributed in space in _______ filaments surrounding empty voids.

A

in long, narrow

96
Q

The observed distribution of matter in the Universe is best understood as being caused by the clumping of _______ in the early universe causing clumping of dark matter.

A

. clumping of normal matter

97
Q

The evolution of the distribution of dark and normal matter were ____ because dark matter does not interact with ____ forces

A

​different —— forces

98
Q

dark matter began clumping to to tiny variation in ____ at the moment of the _____

A

density —— Big Bang

99
Q

The Hubble time only describes a Universe that is totally ____

A

open

100
Q

dark matter must be

A

hyper-baryonic

101
Q

Dark energy is the term used to describe an effect that works against ____ to accelerate the ____ of the universe

A

gravity —- expansion

102
Q

The expansion of the Universe was _____ in the early universe when galaxies were close to each other and has ______ thereafter

A

slower——
accelerated

103
Q

The acceleration of the Universe depends on the effect of baryons matter and dark matter being greater than the effect of _____ ______

A

dark energy.

104
Q

The four fundamental forces in the Universe are the ___ forces.

A

Gravity, weak, electro, strong
G
W
E
S

105
Q

The separation of the strong force and the electroweak force provided the ____ for a rapid ___ of the early universe

A

energy —- inflation

106
Q

If the dark energy is described by the cosmological constant, then the _____ Universe is ____ and will expand forever.

A

flat; accelerating

107
Q

The flatness problem and the horizon problem can be explained by ____

A

the inflationary universe hypothesis

108
Q

Scientists who study the Universe as a whole are called _______________

A

cosmologists

109
Q

The radiation detected by Penzias and Wilson is sometime referred to as CMBR, which stands for
_______________ radiation

A

cosmic microwave

110
Q

Einstein’s theory of mass-energy equivalence shows that high-energy photons can convert into matter
and _______________

A

antimatter

111
Q

The heaviest element created in the big bang, in tiny amounts, is _______________

A

lithium

112
Q

The gas created by the big bang was so hot that it was completely _______________ until the
Universe was no longer radiation-dominated

A

ionized

113
Q

The cosmic microwave background radiation comes from the time when neutral hydrogen atoms
formed in the process of _______________

A

recomination

114
Q

. The Universe is _______________ because it looks the same in any direction you observe it.

A

isotropic

115
Q

The fact that the properties of the Universe are close to the dividing line between open and closed
Universes refers to the _______________ proble

A

flatness

116
Q

The fact that the cosmic microwave background radiation has almost exactly the same temperature in
every direction is referred to as the _______________ problem

A

horizon

117
Q

The _______________ universe hypothesis predicts a sudden, temporary episode of rapid, enormous
expansion of the early Universe

A

inflationary

17-17 (1 decks)

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