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# Large Scale Structure - PowerPoint PPT Presentation

Large Scale Structure. Outline. Homework (don ’ t forget them) Final Monday, 9:45. bring a scantron; good eraser, or extra scantron; sharp pencils calculator Review Hubble ’ s Law Large Scale Structure. Probable Job Opportunity.

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• Homework (don’t forget them)

• Final Monday, 9:45.

• bring a scantron; good eraser, or extra scantron; sharp pencils

• calculator

• Review Hubble’s Law

• Large Scale Structure

4

• The Academic Success Program regularly funds Astronomy Tutors/ Study Group leaders. If you might be interested in this for next fall, please let me know via email.

5

The Tully-Fisher Relation exists between the galaxy's luminosity and its:

A) color.

B) size.

C) age.

D) rotation.

6

The Tully-Fisher Relation exists between the galaxy's luminosity and its:

A) color.

B) size.

C) age.

D) rotation.

7

What method would be most appropriate to determine the distance to a nearby galaxy?

A) Spectroscopic parallax

B) Cepheid variables

C) Hubble’s law

8

What method would be most appropriate to determine the distance to a nearby galaxy?

A) Spectroscopic parallax

B) Cepheid variables

C) Hubble’s law

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Large-Scale Structure distance to a nearby galaxy?

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Figure 16.3 distance to a nearby galaxy?Cosmic Distance Ladder

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Large-Scale Structure distance to a nearby galaxy?

• Use the scale of 1m = 1 A.U.

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Large-Scale Structure distance to a nearby galaxy?

• Use the scale of 1m = 1 A.U.

• The Earth is 1 m from the Sun

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Large-Scale Structure distance to a nearby galaxy?

• Use the scale of 1m = 1 A.U.

• The Earth is 1 m from the Sun

• The Nearest star is near Albuquerque

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Large-Scale Structure distance to a nearby galaxy?

• Use the scale of 1m = 1 A.U.

• The Earth is 1 m from the Sun

• The Nearest star is near Albuquerque

• The center of the Milky Way galaxy would be 4 times as far as the moon.

15

Large-Scale Structure distance to a nearby galaxy?

• Use the scale of 1m = 1 A.U.

• The Earth is 1 m from the Sun

• The Nearest star is near Albuquerque

• The center of the Milky Way galaxy would be 4 times as far as the moon.

• The Andromeda galaxy would be near Mars

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Figure 16.3 distance to a nearby galaxy?Cosmic Distance Ladder

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Large-Scale Structure distance to a nearby galaxy?

• Redshift surveys of galaxies are used to determine the large-scale structure of the universe.

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Figure 16.9 distance to a nearby galaxy?First Galaxy Survey from the mid-1980’s

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Figure 16.10 distance to a nearby galaxy?The Local Universe

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Large-Scale Structure distance to a nearby galaxy?

• Redshift surveys of galaxies are used to determine the large-scale structure of the universe.

• Observed structure includes:

• Strings

• Filaments

• Voids

• The most likely explanation is a slice through “Bubbles.”

• Only a few of these “slices” have been completed.

21

Figure 17.1 distance to a nearby galaxy?Galaxy Survey

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Galaxy Survey distance to a nearby galaxy?

• The universe is homogeneous - it looks the same everywhere

• The universe is isotropic - it looks the same in all directions

• Cosmological principle - the universe is isotropic and homogeneous.

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Tools to study structure.. distance to a nearby galaxy?

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Central Black Hole distance to a nearby galaxy?

• http://www.astro.ucla.edu/~ghezgroup/gc/pictures/orbitsMovie.shtml

• ~4x106 Solar Masses

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Quasars distance to a nearby galaxy?

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Quasars distance to a nearby galaxy?

• Quasars are the active nuclei of very distant galaxies. (Cannot observe the “rest” of the quasar’s galaxy.)

• Energy output ~1000x Milky Way.

• Very large redshifts = Very distant.

• Can use spectra to study closer material.

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Figure 16.12 distance to a nearby galaxy?Twin Quasar

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Figure 16.13 distance to a nearby galaxy?Gravitational Lens

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Figure 16.14 distance to a nearby galaxy?Einstein Cross

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Figure 16.15 distance to a nearby galaxy?Galaxy Cluster Lensing

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Figure 16.16 distance to a nearby galaxy?Dark Matter Map

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Figure 16.11 distance to a nearby galaxy?Absorption Line “Forest”

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Review Questions distance to a nearby galaxy?

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RR Lyrae stars helped astronomers to: distance to a nearby galaxy?

A) Find the distance to nearby galaxies

B) Determine the center of the Milky Way

C) Verify spectroscopic parallax

D) Complete the H-R diagram

35

RR Lyrae stars helped astronomers to: distance to a nearby galaxy?

A) Find the distance to nearby galaxies

B) Determine the center of the Milky Way

C) Verify spectroscopic parallax

D) Complete the H-R diagram

36

What does the Hubble constant measure? distance to a nearby galaxy?

A) The density of galaxies in the universe

B) The luminosity of distant galaxies

C) The rate of expansion of the universe

D) the speed of a galaxy of known redshift

E) the reddening of light by intergalactic dust clouds

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What does the Hubble constant measure? distance to a nearby galaxy?

A) The density of galaxies in the universe

B) The luminosity of distant galaxies

C) The rate of expansion of the universe

D) the speed of a galaxy of known redshift

E) the reddening of light by intergalactic dust clouds

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What method would not be appropriate to determine the distance to a nearby galaxy?

A) Tully-Fisher relationship

B) Cepheid variables

C) Hubble’s law

D) Type I Supernovae

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What method would not be appropriate to determine the distance to a nearby galaxy?

A) Tully-Fisher relationship

B) Cepheid variables

C) Hubble’s law

D) Type I Supernovae

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Olber distance to a nearby galaxy?’s Paradox

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Olber distance to a nearby galaxy?’s Paradox

• Why isn’t the sky bright?

• If the universe is infinite, no matter which way you look, you should see a star.

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Figure 17.2 distance to a nearby galaxy?Olbers’s Paradox

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Olber distance to a nearby galaxy?’s Paradox

• Why isn’t the sky bright?

• If the universe is infinite, no matter which way you look, you should see a star.

• Since the sky is not bright, either…

• Universe is finite.

• Universe evolves with time.

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The Big Bang distance to a nearby galaxy?

• At some time in the past, everything was at a single point.

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The Big Bang distance to a nearby galaxy?

• At some time in the past, everything was at a single point.

• When - Approximately 14 billion years ago.

• The Big Bang provides the resolution of Olber’s Paradox

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Figure 17.3 distance to a nearby galaxy?Receding Galaxies - where was the Big Bang?

• The Big Bang happened everywhere at once.

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Chapter 17 distance to a nearby galaxy?Ultra Deep Field - more than 1000 galaxies are in this picture. Total estimate for the universe - ~40,000,000,000.

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Chapter 17 distance to a nearby galaxy?

Cosmology

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Cosmology distance to a nearby galaxy?

• How big is the universe?

• How long has it been here?

• How did it start?

• How long will it last?

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The Fate of the Universe distance to a nearby galaxy?

• Will it keep expanding forever?

• Will gravity cause it to collapse?

51

From closest to farthest, which methods are used to find the distance to something?

A) radar, spectroscopic parallax, Cepheid variables

B) radar, RR Lyrae variables, spectroscopic parallax

C) parallax, Cepheid variables, RR Lyrae variables

D) Tully Fisher relation, Cepheid variables, parallax

52

From closest to farthest, which methods are used to find the distance to something?

A) radar, spectroscopic parallax, Cepheid variables

B) radar, RR Lyrae variables, spectroscopic parallax

C) parallax, Cepheid variables, RR Lyrae variables

D) Tully Fisher relation, Cepheid variables, parallax

53

Interstellar gas is composed mainly of: distance to something?

A) only hydrogen.

B) some hydrogen, but mainly carbon dioxide.

C) 10% hydrogen, 90% helium by numbers of atoms.

D) 75% hydrogen, 25% helium by weight.

E) ammonia, methane, and water vapor.

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Interstellar gas is composed mainly of: distance to something?

A) only hydrogen.

B) some hydrogen, but mainly carbon dioxide.

C) 10% hydrogen, 90% helium by numbers of atoms.

D) 75% hydrogen, 25% helium by weight.

E) ammonia, methane, and water vapor.

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What is the single most important determinant of the temperature, density, radius, luminosity, and pace of evolution of a protostar?

A) its mass

B) its composition

C) its molecules

D) its magnetic field

E) its spin

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What is the single most important determinant of the temperature, density, radius, luminosity, and pace of evolution of a protostar?

A) its mass

B) its composition

C) its molecules

D) its magnetic field

E) its spin

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Which of these lies ahead for our Sun? temperature, density, radius, luminosity, and pace of evolution of a protostar?

A) supernova of type II

B) brown dwarf

C) nova

D) planetary nebula

E) pulsar

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Which of these lies ahead for our Sun? temperature, density, radius, luminosity, and pace of evolution of a protostar?

A) supernova of type II

B) brown dwarf

C) nova

D) planetary nebula

E) pulsar

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A massive object, heavier than the Sun, which could fit inside a city, is a:

A) asteroid

B) white dwarf

C) neutron star

D) brown dwarf

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A massive object, heavier than the Sun, which could fit inside a city, is a:

A) asteroid

B) white dwarf

C) neutron star

D) brown dwarf

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It is easiest to spot a newly formed protostar with which types of telescopes?

A) ultraviolet scopes at the South Pole, through the ozone hole

B) radio telescopes with the VLA in New Mexico

C) x-ray telescopes like Chandra, up in orbit

D) visible light scopes on Mount Palomar

E) infrared scopes on Mauna Kea

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It is easiest to spot a newly formed protostar with which types of telescopes?

A) ultraviolet scopes at the South Pole, through the ozone hole

B) radio telescopes with the VLA in New Mexico

C) x-ray telescopes like Chandra, up in orbit

D) visible light scopes on Mount Palomar

E) infrared scopes on Mauna Kea

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Three Minute Paper types of telescopes?

• Write 1-3 sentences.

• What was the most important thing you learned today?

• What questions do you still have about today’s topics?

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