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Galaxies and Cosmology. 5 points, vt-2007 Teacher: Göran Östlin Lectures 7-9. Theoretical cosmology. Problems with Newtonian Gravity and Mechanics: Gravity Inertial frames - absolute space and time General Relativity - matter curves space (& time), EP G +  g = -8G T / c 4

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Galaxies and cosmology

Galaxies and Cosmology

5 points, vt-2007

Teacher: Göran Östlin

Lectures 7-9

Theoretical cosmology

Theoretical cosmology

Problems with Newtonian Gravity and Mechanics:


Inertial frames - absolute space and time

General Relativity - matter curves space (& time), EP

G + g = -8G T / c4

G, g, T are tensors

Geometry: line element

Cosmological principle: isotropy, homogeneity

Galaxies and cosmology

Gravity can in General Relativity be regarded as a

space curvature rather than a force

Orbit of earth a straight line in space-time

Geometrical cosmology line elements

Geometrical cosmology: Line elements

2-dim cartesian

3-dim cartesian

3-dim spherical

2-dim curved space

Special relativity

Timelike separation

Null separation (light)

Spacelike separation

Robertson walker line element

Robertson-Walker line element

Simplest 4-dim (3 space, 1 time) space that fulfills the cosmological principle

Only R(t)changes with time -> homogeneously expanding or contracting space



z = (obs - em)/ em = obs / em - 1 =  / 

vr = z  c

z = H0  d / c =>v r= H0  d

Valid up to z  0.2

NB Special relativistic formula not more accurate

General relativistic description of space-time required





Cosmic time vs redshift

Cosmic time vs redshift

Galaxies and cosmology

Newtonian derivation of Friedman equations

(see handwritten handouts)

Frw models summary

FRW-models, summary

Galaxies and cosmology

Properties of the

Universe set by

3 parameters:

m, , k of

Which only 2 are


m + + k = 1

Galaxies and cosmology

Age of universe for: closed(1), critical(2), open(3), and acellerating(4) models

Galaxies and cosmology

Active galaxies / Active galactic nuclei (AGN)

Compact regions in the centre of galaxies with

Great luminosity and rapid variability.

Common characteristics:

Broad emission lines, high excitation, jets

flat spectral energy distribution(non thermal)

Many classses:

-Seyfert 1 & 2

-Quasars, QSOs

-Radio galaxies

-Bl Lac, Blazars

… are all the same?

Galaxies and cosmology

Quasars 1960’s and onwards

1963 Marten Schmidt

determines redshift

for the first time

Compare GRBs

Seyfert spectra

Seyfert spectra

Broad and narrow lines

Permitted and forbidden lines

Active galaxies active galactic nuclei agn

Active galaxies / Active galactic nuclei (AGN)

Central engine

variability put limit on size: R ≤ c var

Schwarzschild radius: Rs = 2 G M / c2

Rs = size approx Uranus orbit for 109 M

Accretion allows conversion of 0.1mc2

(fusion only 0.7%)

Radiation pressure will larger than gravity if L > LEDD

Accretion disk very hot continuum source => X-rays

Broad line region, dense ionised clouds, rapid moving

Narrow line region, dilute ionised clouds, slower

reverbration mapping

Obscuring torus with dust and molecular gas,

sublimation evacuate central part -> torus

Relativistic (superluminal) Jets, and radio Lobes

Galaxies and cosmology

QSO spectrum

Note the broad emission lines and blue continuum

Galaxies and cosmology

Radio images of radio galaxies

Synchrotron emission

Galaxies and cosmology

M87 (radio galaxy): jets both in optical and radio

Jets often one-sided due to relativistic beaming

Galaxies and cosmology

F_lam vs F_lam*lam

Blazar spectra

Blazar spectra

Superluminal motion

Superluminal motion


Motions !

Qso absorption lines

QSO absorption lines

Unified agn models

Unified AGN models

Idea: all AGN are basically the same phenomena

Differing due to different viewing angle and scale:

Face on view: see all components: Sy1, QSO

if looking into jet: Bl Lac (Blazar)

Edge on view: see only hot torus and NLR, Sy2

Why some radio loud while others not?

Unified BH model not perfect, but nothing else works

Galaxies and cosmology

Unified model of AGN

Galaxies and cosmology

Unified Model

Galaxies and cosmology

Spiral seyfert2 with radio jets


Qso evolution where are they now

QSO evolution - where are they now?

Debate if fall off

at z>3 is real

There must be many dead QSOs around in the local universe!

Kinematical evidence for bh in m87

Kinematical evidence for BH in M87

+ Grav redshifted X-ray em-lines detected in Sy1’s

Galaxies and cosmology

Relation between black hole mass and sigma of host

galaxy: a realtion between BH and Spheroid Mass

-- Black Hole doesn’t care about disk

-- Co-evolves with spheroid/bulge!

Clusters and large scale structure chapt 4

Clusters And Large Scale Structure (chapt. 4)

Galaxies and cosmology



Sex A

Galaxies and cosmology

Tidal drag on NGC205 from M31

Local group

Local Group

Galaxies and cosmology





Caught in


Rich clusters virgo and coma irregular vs regular

Rich clusters: Virgo and Comairregular vs regular

(large spiral fraction) (mostly ”early” types))

(more relaxed)

Hot gas in clusters x ray emitting through thermal bremsstrahlung

Hot gas in clustersX-ray emitting through thermal bremsstrahlung

Efficient way of finding


Galaxies and cosmology

Perseus cluster central galaxy

Butcher oemler effect etc

Butcher-Oemler effect, etc:

As we look back in time, the spiral fraction of

Rich clusters become higher and higher (BO)

Cluster and Galaxy transformation

Interactions: galaxy mergers

cluster merger

galaxy harassment

ram pressure stripping

diffuse intracluster light: stars + gas

vs Hot intracluster gas

Masses of clusters

Masses of clusters:

Virial theorem: M = RAv2 / G

- does it apply?

X-ray gas in Hydrostatic equilibrium - does it apply?

Gravitational lensing:

it does apply but only gives mass contrast

- Methods agree fairly well (factor of 2)

Gravitational lensing

Gravitational lensing

Galaxies and cosmology

Einstein ring

Abell 2218 strong lensing cf weak lensing statistical

Abell 2218, strong lensingcf weak lensing (statistical)

Galaxies and cosmology

Angular distribution of Abell-clusters

Brightest cluster galaxy method allows

rough space distribution to be inferred

Virgo supercluster

Virgo supercluster


-Not relaxed



Galaxies and cosmology

Distribution of galaxies on the sky

Sponge like topology of universe

Sponge-like topology of universe




Great wall


Finger of god

Galaxies and cosmology


Galaxies and cosmology

Distribution of red and blue galaxies in space

Intergalactic matter

Intergalactic matter

Gunn peterson effect

Gunn-Peterson effect

Cosmic shear

Cosmic shear


- Effect on each individual galaxy tiny

- Only visible through lareg and deep samples

Measuring clustering

Measuring Clustering

- Count in cells

- 2-point corellation function

Galaxies and cosmology

Peculiar velocities

Deviations from the

Hubble flow

Basic friedmann model universa see handout papers

Basic Friedmann model universa(see handout papers)

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