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 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 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 Simplest 4-dim (3 space, 1 time) space that fulfills the cosmological principle Only R(t) changes with time -> homogeneously expanding or contracting space

Redshisfts… z = ( obs - em )/ em = obs / em - 1 =  / v r = z  c z = H 0  d / c =>v r = H 0  d Valid up to z  0.2 NB Special relativistic formula not more accurate General relativistic description of space-time required

Redshift

Redshifts…

Cosmic time vs redshift

Newtonian derivation of Friedman equations (see handwritten handouts)

FRW-models, summary

Properties of the Universe set by 3 parameters:  m,  ,  k of Which only 2 are Independent:  m +   +  k = 1

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

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?

Quasars 1960’s and onwards 1963 Marten Schmidt determines redshift for the first time Compare GRBs

Seyfert spectra Broad and narrow lines Permitted and forbidden lines

Active galaxies / Active galactic nuclei (AGN) Central engine variability put limit on size: R ≤ c  var Schwarzschild radius: R s = 2 G M / c 2 R s = size approx Uranus orbit for 10 9 M  Accretion allows conversion of 0.1mc 2 (fusion only 0.7%) Radiation pressure will larger than gravity if L > L EDD 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 Note the broad emission lines and blue continuum

Radio images of radio galaxies Synchrotron emission

M87 (radio galaxy): jets both in optical and radio Jets often one-sided due to relativistic beaming

F_lam vs F_lam*lam

Blazar spectra

Superluminal motion Superluminal Motions !

QSO absorption lines

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

Unified model of AGN

Unified Model

Spiral seyfert2 with radio jets Seyfert1

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

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)

M33 Sex A LeoI

Tidal drag on NGC205 from M31

Local Group

HCG31 Galaxy Evolution/ Transformation Caught in action

Rich clusters: Virgo and Coma irregular vs regular (large spiral fraction) (mostly ”early” types)) (more relaxed)

Hot gas in clusters X-ray emitting through thermal bremsstrahlung Efficient way of finding clusters

Perseus cluster central galaxy

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: Virial theorem: M = R A  v 2 / 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

Einstein ring

Abell 2218, strong lensing cf weak lensing (statistical)

Angular distribution of Abell-clusters Brightest cluster galaxy method allows rough space distribution to be inferred

Virgo supercluster Bound? -Not relaxed LargeScale Flows

Distribution of galaxies on the sky

Sponge-like topology of universe CfA Redshift Survey Great wall Voids! Finger of god

SDSS

Distribution of red and blue galaxies in space

Intergalactic matter

Gunn-Peterson effect

Cosmic shear Challenging! - Effect on each individual galaxy tiny - Only visible through lareg and deep samples

Measuring Clustering - Count in cells - 2-point corellation function

Peculiar velocities Deviations from the Hubble flow

Basic Friedmann model universa (see handout papers)