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Galaxies and Cosmology

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

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  1. Galaxies and Cosmology 5 points, vt-2007 Teacher: Göran Östlin Lectures 7-9

  2. 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 / c4 G, g, T are tensors Geometry: line element Cosmological principle: isotropy, homogeneity

  3. Gravity can in General Relativity be regarded as a space curvature rather than a force Orbit of earth a straight line in space-time

  4. 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

  5. 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

  6. Redshisfts… 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

  7. Redshift

  8. Redshifts…

  9. Cosmic time vs redshift

  10. Newtonian derivation of Friedman equations (see handwritten handouts)

  11. FRW-models, summary

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

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

  14. 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?

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

  16. Seyfert spectra Broad and narrow lines Permitted and forbidden lines

  17. 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

  18. QSO spectrum Note the broad emission lines and blue continuum

  19. Radio images of radio galaxies Synchrotron emission

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

  21. F_lam vs F_lam*lam

  22. Blazar spectra

  23. Superluminal motion Superluminal Motions !

  24. QSO absorption lines

  25. 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

  26. Unified model of AGN

  27. Unified Model

  28. Spiral seyfert2 with radio jets Seyfert1

  29. 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!

  30. Kinematical evidence for BH in M87 + Grav redshifted X-ray em-lines detected in Sy1’s

  31. 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!

  32. Clusters And Large Scale Structure (chapt. 4)

  33. M33 LeoI Sex A

  34. Tidal drag on NGC205 from M31

  35. Local Group

  36. HCG31 Galaxy Evolution/ Transformation Caught in action

  37. Rich clusters: Virgo and Comairregular vs regular (large spiral fraction) (mostly ”early” types)) (more relaxed)

  38. Hot gas in clustersX-ray emitting through thermal bremsstrahlung Efficient way of finding clusters

  39. Perseus cluster central galaxy

  40. 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

  41. 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)

  42. Gravitational lensing

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