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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

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

Newtonian derivation of Friedman equations

(see handwritten handouts)

Properties of the

Universe set by

3 parameters:

m, , k of

Which only 2 are


m + + k = 1

Active galaxies / Active galactic nuclei (AGN) acellerating(4) models

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?

Quasars 1960’s and onwards acellerating(4) models

1963 Marten Schmidt

determines redshift

for the first time

Compare GRBs

Seyfert spectra
Seyfert spectra acellerating(4) models

Broad and narrow lines

Permitted and forbidden lines

Active galaxies active galactic nuclei agn
Active galaxies / Active galactic nuclei (AGN) acellerating(4) models

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

QSO spectrum acellerating(4) models

Note the broad emission lines and blue continuum

Radio images of radio galaxies acellerating(4) models

Synchrotron emission

M87 (radio galaxy): jets both in optical and radio acellerating(4) models

Jets often one-sided due to relativistic beaming

F_lam vs F_lam*lam acellerating(4) models

Blazar spectra
Blazar spectra acellerating(4) models

Superluminal motion
Superluminal motion acellerating(4) models


Motions !

Qso absorption lines
QSO absorption lines acellerating(4) models

Unified agn models
Unified AGN models acellerating(4) 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

Unified model of AGN acellerating(4) models

Unified Model acellerating(4) models

Spiral seyfert2 with radio jets acellerating(4) models


Qso evolution where are they now
QSO evolution - where are they now? acellerating(4) models

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 acellerating(4) models

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

Relation between black hole mass and sigma of host acellerating(4) models

galaxy: a realtion between BH and Spheroid Mass

-- Black Hole doesn’t care about disk

-- Co-evolves with spheroid/bulge!

M33 acellerating(4) models


Sex A

Tidal drag on NGC205 from M31 acellerating(4) models

Local group
Local Group acellerating(4) models

HCG31 acellerating(4) models




Caught in


Rich clusters virgo and coma irregular vs regular
Rich clusters: Virgo and Coma acellerating(4) modelsirregular vs regular

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

(more relaxed)

Hot gas in clusters x ray emitting through thermal bremsstrahlung
Hot gas in clusters acellerating(4) modelsX-ray emitting through thermal bremsstrahlung

Efficient way of finding


Perseus cluster central galaxy acellerating(4) models

Butcher oemler effect etc
Butcher-Oemler effect, etc: acellerating(4) models

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: acellerating(4) models

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 acellerating(4) models

Einstein ring acellerating(4) models

Abell 2218 strong lensing cf weak lensing statistical
Abell 2218, strong lensing acellerating(4) modelscf weak lensing (statistical)

Angular distribution of Abell-clusters acellerating(4) models

Brightest cluster galaxy method allows

rough space distribution to be inferred

Virgo supercluster
Virgo supercluster acellerating(4) models


-Not relaxed



Distribution of galaxies on the sky acellerating(4) models

Sponge like topology of universe
Sponge-like topology of universe acellerating(4) models




Great wall


Finger of god

SDSS acellerating(4) models

Distribution of acellerating(4) modelsred and blue galaxies in space

Intergalactic matter
Intergalactic matter acellerating(4) models

Gunn peterson effect
Gunn-Peterson effect acellerating(4) models

Cosmic shear
Cosmic shear acellerating(4) models


- Effect on each individual galaxy tiny

- Only visible through lareg and deep samples

Measuring clustering
Measuring Clustering acellerating(4) models

- Count in cells

- 2-point corellation function

Peculiar velocities acellerating(4) models

Deviations from the

Hubble flow

Basic friedmann model universa see handout papers
Basic Friedmann model universa acellerating(4) models(see handout papers)