Astrophysik 2: Cosmology at ETHZ - ETH Zurich | Flashcards & Summaries

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Lernmaterialien für Astrophysik 2: Cosmology an der ETHZ - ETH Zurich

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TESTE DEIN WISSEN

Whats Baryogengesis

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TESTE DEIN WISSEN

Baryogenesis is a mechanism which explains the observed asymmetry between baryons and antibaryons.

(we do not observe a significant abundance of anti baryons)

Lösung ausblenden
TESTE DEIN WISSEN

What are the Distance Scales (in parsecs) of the following observations?

  • Galaxy
  • Galaxy Cluster
  • Homogeneity
  • Observable Universe
Lösung anzeigen
TESTE DEIN WISSEN
  • Galaxy 10^4 pc
  • Galaxy Cluster: 10^6 pc
  • Homogeneity: 10^8 pc
  • Observable Universe:  10^10 pc
Lösung ausblenden
TESTE DEIN WISSEN

What is the Age of the Sun and the Age of the Universe?


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TESTE DEIN WISSEN
  • Sun: 4.6 gyr
  • Universe: 14 gyr
Lösung ausblenden
TESTE DEIN WISSEN

Whats the definition of Luminosity and (Bolometric Flux)?

Lösung anzeigen
TESTE DEIN WISSEN
  • Luminosity is an intrinsic quantity of an object:
    • L = energy/time
  • Flux is an observable quantity
    • f = L/4*pi*r^2 = Luminosity/area
  • Bolometric Flux: Flux over all Wavelengths: f
Lösung ausblenden
TESTE DEIN WISSEN

Give the definition of the Cosmical Principle.

Whats the root of the Cosmical Principle?


Lösung anzeigen
TESTE DEIN WISSEN

The universes is homogenous and isotropic on sufficient large scales. 

(>100Mpc = 10^8pc is Homogenity observed.)


The Cosmic Principle is a Generalization of the Copernican Principle: "Our place in the universe is indifferent from another place in the universe"

Lösung ausblenden
TESTE DEIN WISSEN

What is a geodesic ?

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TESTE DEIN WISSEN

A geodesic is a curve representing the shortest path between two point on a surface.

Lösung ausblenden
TESTE DEIN WISSEN

Describe the Geometry of the FRW Metric for the three Cases of different curvature.



Lösung anzeigen
TESTE DEIN WISSEN
  • K=0: Flat space time: 
    • Plane expanding or contracting
  • K=+1: Closed Space Time, Positive Curvature:
    • 3D Sphere in a 4D Euclidean space
  • K = -1: Open Space Time, Negative Curvatur:
    • 3D Hyperbole in a 4D Minkowski space
Lösung ausblenden
TESTE DEIN WISSEN

Whats the definition of the redshift? (equation)

Give two equations showing how one can calculate the Distance and the scale factor at emission time from the redshift. 

Lösung anzeigen
TESTE DEIN WISSEN

1+z = lambda(observed)/lambda(emitted) ( = a0/a(emitted)


D = c*z/H (for small z)

a = 1/1+z (for a0 =1)




Lösung ausblenden
TESTE DEIN WISSEN

Give the mathematical definition and an estimate for the Hubble parameter. What does the Hubble parameter describe?

Lösung anzeigen
TESTE DEIN WISSEN

H = 1/a * da/dt

H  = 70 km/s 1/Mpc


The Hubble parameter describes the rate of change of the proper distance between two fundamental observers.

Lösung ausblenden
TESTE DEIN WISSEN

Whats the Big-Bang paradigm?

Lösung anzeigen
TESTE DEIN WISSEN

The Universe expands and cools down.

Lösung ausblenden
TESTE DEIN WISSEN

Name the four important transitions in the thermal evolution of the universe after the Big-Bang.
What happened at those transition, which Era do they belong, and what was the Temperature, Energy and Time of this transitions?

Lösung anzeigen
TESTE DEIN WISSEN
  • Quark Hadron transition
    • Quarks combine to Hadrons (baryons, mesons: they decay)
    • Radiation Era: T = 3*10^12 K, t=10^-5 s, E=300 MeV
  • e+-e- Anhilation
    • Neutrino and Anti-Neutrino of e decouple, photons heat:
    • Radiation Era: T= 5*10^9 K, t=4 s, E=5 MeV
  • Big Bang Nucleosynthesis
    • n & p combine and form light nuclei
    • Radiation Era: 10^8K, t-few minutes, E-MeV
  • Recombination
    • electrons and nuclei combine anf form atoms
    • universe becomes neutral to photons which decouple -> transparent
    • last scattering surface yields: Cosmic Microwave Background 
    • Matter Era: T=4000K, E=eV, t=2*10^5 yr
Lösung ausblenden
TESTE DEIN WISSEN

In what state was the Universe before the Quark-Hadron Transition.

Lösung anzeigen
TESTE DEIN WISSEN
  • Temperature of around 10^13 K
    • Energy still higher than the binding energy of baryons
  • Universe was in a form of a "quark soup", which consists of quarks, leptons and photons.
Lösung ausblenden
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  • 88 Lernmaterialien

Beispielhafte Karteikarten für deinen Astrophysik 2: Cosmology Kurs an der ETHZ - ETH Zurich - von Kommilitonen auf StudySmarter erstellt!

Q:

Whats Baryogengesis

A:

Baryogenesis is a mechanism which explains the observed asymmetry between baryons and antibaryons.

(we do not observe a significant abundance of anti baryons)

Q:

What are the Distance Scales (in parsecs) of the following observations?

  • Galaxy
  • Galaxy Cluster
  • Homogeneity
  • Observable Universe
A:
  • Galaxy 10^4 pc
  • Galaxy Cluster: 10^6 pc
  • Homogeneity: 10^8 pc
  • Observable Universe:  10^10 pc
Q:

What is the Age of the Sun and the Age of the Universe?


A:
  • Sun: 4.6 gyr
  • Universe: 14 gyr
Q:

Whats the definition of Luminosity and (Bolometric Flux)?

A:
  • Luminosity is an intrinsic quantity of an object:
    • L = energy/time
  • Flux is an observable quantity
    • f = L/4*pi*r^2 = Luminosity/area
  • Bolometric Flux: Flux over all Wavelengths: f
Q:

Give the definition of the Cosmical Principle.

Whats the root of the Cosmical Principle?


A:

The universes is homogenous and isotropic on sufficient large scales. 

(>100Mpc = 10^8pc is Homogenity observed.)


The Cosmic Principle is a Generalization of the Copernican Principle: "Our place in the universe is indifferent from another place in the universe"

Mehr Karteikarten anzeigen
Q:

What is a geodesic ?

A:

A geodesic is a curve representing the shortest path between two point on a surface.

Q:

Describe the Geometry of the FRW Metric for the three Cases of different curvature.



A:
  • K=0: Flat space time: 
    • Plane expanding or contracting
  • K=+1: Closed Space Time, Positive Curvature:
    • 3D Sphere in a 4D Euclidean space
  • K = -1: Open Space Time, Negative Curvatur:
    • 3D Hyperbole in a 4D Minkowski space
Q:

Whats the definition of the redshift? (equation)

Give two equations showing how one can calculate the Distance and the scale factor at emission time from the redshift. 

A:

1+z = lambda(observed)/lambda(emitted) ( = a0/a(emitted)


D = c*z/H (for small z)

a = 1/1+z (for a0 =1)




Q:

Give the mathematical definition and an estimate for the Hubble parameter. What does the Hubble parameter describe?

A:

H = 1/a * da/dt

H  = 70 km/s 1/Mpc


The Hubble parameter describes the rate of change of the proper distance between two fundamental observers.

Q:

Whats the Big-Bang paradigm?

A:

The Universe expands and cools down.

Q:

Name the four important transitions in the thermal evolution of the universe after the Big-Bang.
What happened at those transition, which Era do they belong, and what was the Temperature, Energy and Time of this transitions?

A:
  • Quark Hadron transition
    • Quarks combine to Hadrons (baryons, mesons: they decay)
    • Radiation Era: T = 3*10^12 K, t=10^-5 s, E=300 MeV
  • e+-e- Anhilation
    • Neutrino and Anti-Neutrino of e decouple, photons heat:
    • Radiation Era: T= 5*10^9 K, t=4 s, E=5 MeV
  • Big Bang Nucleosynthesis
    • n & p combine and form light nuclei
    • Radiation Era: 10^8K, t-few minutes, E-MeV
  • Recombination
    • electrons and nuclei combine anf form atoms
    • universe becomes neutral to photons which decouple -> transparent
    • last scattering surface yields: Cosmic Microwave Background 
    • Matter Era: T=4000K, E=eV, t=2*10^5 yr
Q:

In what state was the Universe before the Quark-Hadron Transition.

A:
  • Temperature of around 10^13 K
    • Energy still higher than the binding energy of baryons
  • Universe was in a form of a "quark soup", which consists of quarks, leptons and photons.
Astrophysik 2: Cosmology

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