Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter...

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Hubble diagram for Cepheid distances from Choudhuri Astrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1

Transcript of Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter...

Page 1: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Hubble diagram for Cepheid distances

from Choudhuri

Astrophysics I, Lecture Slides – Chapter 9, ETH Zurich

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Page 2: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Redshift surveys

from Choudhuri 2

Page 3: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

from Choudhuri 3

Page 4: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

A spherical and a hyperbolic surface

from Choudhuri 4

Page 5: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

from Choudhuri 5

Page 6: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Newtonian cosmology model

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Page 7: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Solutions of the Friedmann equation

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Page 8: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Cosmic Microwave Background (CMB)

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Page 9: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

An accelerating universe ?

SN Ia at large z are too faint for aFriedmann-type universe

Interpretation: accelerating expansion Λ universe is flat universe is older

but: Λ unclear

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Page 10: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

from frigg.physastro.mnsu.edu 10

Page 11: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

from Choudhuri 11

Page 12: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Primordial abundances vs. η=nb/nγ

from Choudhuri 12

Page 13: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

CMB-fluctuationstemperature fluctuation at a level of ΔT/T ≈ 10-5

these are the seeds for the later structure formation

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Page 14: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Structure formation

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Page 15: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Lookback-time vs redshift- with the best telescopes (HST, VLT) the structure formation in the ``early’’

Universe can be observed directly - bright objects can be observed at distances of

> 5 billion ly = lookback time > 5 billion years telescopes are time machines

relation between • redshift and • look-back time

(relative to age of Universe)

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Page 16: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

HDFHubble Deep Field

HDF was 1995 the first very deep observation of galaxies in ther “early” Universe

field: 2.5’ x 2.5’(3x10-8 of the sky)

~3000 objects(~20 stars)

The most distant objects in this field emitted there light only 2-5 billion years after the big bang.

next slide: section on the lower right

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Page 17: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

z=2.80

z=0.50

z=0.68

z=1.24

z=0.76

z=1.06

z=1.01 17

Page 18: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Galaxy statisticsnumber of galaxies per solid angle brighter than a given magnitude limit

in HDF, there are about 10x more galaxies(data points) than expected, assuming that galaxies and galaxy numbers do not change with time (solid lines)

- the excess is particularly strong for irregular/peculiar/merger galaxies(lower right)

Interpretations- galaxies were in the past on average

10x brighter (higher star formation rate) therefore we see more bright galaxies

than expected big excess for colliding galaxies which

result from the ``first’’ assembly of gasrich matter components

GaGalaxy statistic in the HDF(for all galaxies (a) und special types (b,c,d); aus Abraham et al. 1996, (MNRAS 279, L47)

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Page 19: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Quasar number density vs redshift

from Choudhuri

many bright quasars appear at z ≈ 2.5

- BH > 109 Msun

almost no bright quasar at z < 0.2 (last 1 billion years)

Feeding of black holes stopped

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Page 20: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Lyα forest – evolution of the intergalactic medium

- quasars are good background sources for HI Lyα absorption (low ionization clouds)- Lyα along line of sight has lower redshift (to the blue of the Lyα emission)- yields good statistics on the distribution of clouds

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Page 21: Astrophysics I, Lecture Slides – Chapter 9, ETH ZurichAstrophysics I, Lecture Slides – Chapter 9, ETH Zurich 1 Redshift surveys from Choudhuri 2 from Choudhuri 3 A spherical and

Reionization of the Universe

3C 273 z = 0.16

SDSS z = 5.80

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