17-18 Flashcards
(117 cards)
1
Q
Seyfert galaxies appear similar to normal spirals with extremely luminous cores
A
True
2
Q
The broad emission lines of Seyfert galaxies imply high gas speeds in the nucleus.
A
True
3
Q
The luminosity of a Seyfert galaxy varies with a regular period of months or years
A
false
4
Q
Seyfert galaxies rarely show evidence of collisions with other galaxies
A
false
5
Q
Double-lobed radio galaxies are an effect of black hole jets
A
True
6
Q
Quasars are radio sources that look like stars in visible-light photograph
A
True
7
Q
Quasars are isolated supermassive black holes, and not associated with galaxies.
A
false
8
Q
Supermassive black holes are very large, the most massive even larger than our Solar System.
A
false
9
Q
The structure of black hole jets is believed to be controlled by magnetism
A
True
10
Q
Matter flowing into a black hole cools until it is accelerated into a jet
A
false
11
Q
The unified model of active galactic nuclei focuses on differences caused by the age of the central
black hole.
A
false
12
Q
Most supermassive black holes are dormant
A
True
13
Q
Black holes erupt when matter flows into their accretion disk
A
True
14
Q
The size of a galaxy’s central black hole is proportional to the mass of its disk
A
false
15
Q
Quasars are caused by galaxy collisions in the early Universe
A
true
16
Q
Collisions in the early Universe were rare.
A
false
17
Q
Normal galaxies in the present never went through an active galaxy phase
A
false
18
Q
Supermassive have weaker gravity than stellar-mass black holes, producing slower spins for the
infalling matter
A
false
19
Q
Active galactic nuclei were first found through observations in the ____ wavelength band
A
radio
20
Q
Seyfert galaxies are ___
A
spiral galaxies
21
Q
Double-lobed radio galaxies are ____.
A
elliptical galaxies
22
Q
Quasars are ____
A
extremely luminous
23
Q
What is the best description of Hanny’s Voorwerp
A
glowing green
24
Q
The energy output of a Seyfert galaxy ____
A
hundred times the luminosity of the milky way
25
The high luminosity of a Seyfert galaxy is concentrated in a ____
small area
26
Seyfert galaxies are always ____ galaxies
spiral
27
What produces the lobes in double-lobed radio galaxies ____ _____ jets
black hole
28
A supermassive black hole that is erupting may push ____ disk
acceration
29
When they were first discovered, quasars appeared to be ____.
small star objects
30
Quasars have a(n) ____.
extremely high redshift
31
Gas falling into a black hole becomes ____ due to an increase of speed
hot
32
Matter falling into a black hole arranges itself in the shape of a ____
disk that is thick
33
The motion of gas in accretion disks and jets is ____
poorly understood but may relate to magnetism
34
A unified model of active galaxy cores can explain different types of Seyfert galaxies, quasars and
other active galaxy types by differences in the ____
tilt of the accertration disk
35
A supermassive black hole erupts when ____.
a sudden flood of matter flows inward
36
Supermassive black holes erupt in central ____.
bulges
37
Many galaxies with erupting black holes are found in one pair of orbiting ____
galaxies
38
The formation process for supermassive black holes is linked with the formation of galactic central ____.
bulges
39
The formation of a galactic central bulge is believed to ____.
To be a violent process
40
Quasars are common in the early Universe because ____ at that time
galatic collisions were more frequent
41
Quasars ____
are an early stage of the formation of common
42
A galaxy’s supermassive black hole represents about ____ for elliptical galaxies
Half a percent of the mass of the central bulge
43
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
spectral
44
Astronomers conclude that quasars must come from the earliest phases of the Universe because they have a large ____ spectra
redshifted
45
Active galaxies are believed to be the product of collisions and interactions because of the transfer of ___
mattter
46
The accompanying graph shows that quasars formed starting the formation of the ____
universe
47
Most quasars have a redshift between ____ and ____
2 -3
48
Active galaxies were first discovered by observations in the _______________ wavelength band
radio
49
A spiral galaxy with an extremely luminous, active core is called a(n) _______________ galaxy
seyfart
50
Some active radio galaxies exhibit _____ of gas heated by jet
lobes
51
Matter falling into a black hole forms a(n) _______________ disk
acceration
52
Black hole jets are believed to be focused and confined by the enclosing magnetic _____
tubes
53
The Doppler effect in the spectra of quasars show very high _______________
redshifts
54
Ultra luminous radio sources associated with small visible-light objects are called ______.
quesars
55
Matter falling into a black hole converts ________ energy into thermal energy.
Gravitational
56
Active galaxies are the result of galactic _______________
collisions
57
Olber’s paradox is explained by the fact that the Universe is neither static nor infinite in age.
true
58
The “big bang” was an explosion of material that created galaxies flying away from the center of the
explosion.
false
59
Cosmologists cannot begin their history of the big bang at a time of exactly zero because it cannot be
explained by current physics
True
60
The big bang happened everywhere in the Universe at the same time
true
61
Tiny amounts of lithium and beryllium were formed in the big bang
false
62
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.
True
63
After nuclear reactions in the big bang had ended, about 25% of the mass of the Universe was in the
form of helium nuclei
True
64
The Universe is isotropic, but not homogenous
False
65
The cosmological principle states that any observer in any galaxy sees the same general properties for
the Universe.
True
66
The cosmological redshifts of galaxies are Doppler shifts
True
67
All dark matter in our Universe falls into the category of “hot dark matter”
False
68
Normal matter is baryonic
True
69
The expansion of the Universe is acceleratin
True
70
In the early universe, the electromagnetic and strong nuclear forces were joined together to make the
electrostrong force
False
71
Dark energy accounts for about 70% of the critical density of the Universe.
True
72
The decoupling of the strong force from the electroweak force provided energy for a rapid inflation of
the Universe.
True
73
Olber’s paradox states that the sky should ____.
as bright but its not
74
The Universe has ____.
Has no edge nor center
75
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 ____
still
expands
76
The Hubble time is the age ____.
of the universe
77
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
big bang —- any direction at long
look-back time
78
Arno Penzias and Robert Wilson are famous for ____
detecting the large redshift background radiation from the big bang
79
The microwave emission detected by Arno Penzias and Robert Wilson fits a blackbody spectrum with
a temperature of about ____ K
2.7
80
Penzias and Wilson detected microwave radiation because the big bang created longer ____ energy that has been redshifted by expansion
wavelength
81
In the very first phase after the big bang, when the Universe was about a microsecond old, space was
filled with high energy ____.
protons
82
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 ____
Protons and neutrons
83
Einstein’s mass-energy equivalence ( ) is important to the first phases of the big bang in ____ rays photons create matter and _____
. gamma ray ——— antimatter
84
The big bang only created hydrogen and helium (with miniscule amounts of lithium) because elements with an atomic weight of ____or ___ are unstable
5 or 8
85
The cosmic microwave background radiation was emitted during a time when ____ was the important
process in the Universe
Recomination
86
Figure 18-12 (for questions 14-17)
14. One year after the big bang, the temperature of the Universe was approximately ____ ^6 degrees Kelvin
10^6
87
The Universe had a temperature of a few hundred million degrees K at approximately ____ after the
big bang.
one hour
88
The re-ionization of the Universe occurred closest to ____ of degrees Kelvin.
tens
89
The change from a radiation-dominated to a matter-dominated Universe occurred at a temperature
closest to ____ of degrees Kelvin.
Tens of thousands
90
The proper interpretation of a what a galaxy’s redshift measures is the stretching of space between the ____ and the _____
galaxy and the observer
91
Modern observations have shown that the geometry of the Universe is ____ and universe must be _____
flat —— infinite
92
The main criterion for deciding between Universe geometries is ____.
density
93
Which statement about the behavior of Universe geometries is correct?
Closed universes ____ and then ____
expand and then contract
94
Ordinary matter makes up approximately ____ percent of the critical density of the Universe
4.5
95
Clusters of galaxies are distributed in space in _______ filaments surrounding empty voids.
in long, narrow
96
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.
. clumping of normal matter
97
The evolution of the distribution of dark and normal matter were ____ because dark matter does not interact with ____ forces
different —— forces
98
dark matter began clumping to to tiny variation in ____ at the moment of the _____
density —— Big Bang
99
The Hubble time only describes a Universe that is totally ____
open
100
dark matter must be
hyper-baryonic
101
Dark energy is the term used to describe an effect that works against ____ to accelerate the ____ of the universe
gravity —- expansion
102
The expansion of the Universe was _____ in the early universe when galaxies were close to each other and has ______ thereafter
slower——
accelerated
103
The acceleration of the Universe depends on the effect of baryons matter and dark matter being greater than the effect of _____ ______
dark energy.
104
The four fundamental forces in the Universe are the ___ forces.
Gravity, weak, electro, strong
G
W
E
S
105
The separation of the strong force and the electroweak force provided the ____ for a rapid ___ of the early universe
energy —- inflation
106
If the dark energy is described by the cosmological constant, then the _____ Universe is ____ and will expand forever.
flat; accelerating
107
The flatness problem and the horizon problem can be explained by ____
the inflationary universe hypothesis
108
Scientists who study the Universe as a whole are called _______________
cosmologists
109
The radiation detected by Penzias and Wilson is sometime referred to as CMBR, which stands for
_______________ radiation
cosmic microwave
110
Einstein’s theory of mass-energy equivalence shows that high-energy photons can convert into matter
and _______________
antimatter
111
The heaviest element created in the big bang, in tiny amounts, is _______________
lithium
112
The gas created by the big bang was so hot that it was completely _______________ until the
Universe was no longer radiation-dominated
ionized
113
The cosmic microwave background radiation comes from the time when neutral hydrogen atoms
formed in the process of _______________
recomination
114
. The Universe is _______________ because it looks the same in any direction you observe it.
isotropic
115
The fact that the properties of the Universe are close to the dividing line between open and closed
Universes refers to the _______________ proble
flatness
116
The fact that the cosmic microwave background radiation has almost exactly the same temperature in
every direction is referred to as the _______________ problem
horizon
117
The _______________ universe hypothesis predicts a sudden, temporary episode of rapid, enormous
expansion of the early Universe
inflationary
