Galaxy Evolution. Part 5. Jochen Liske Hamburger Sternwarte

Transcription

1 Galaxy Evolution Part 5 Jochen Liske Hamburger Sternwarte jochen.liske@uni-hamburg.de

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5 1. Introduction 2. Overview of galaxies and physical processes 2.1 What is a galaxy? Constituents Structure Main parameters 2.2 Basic elements of galaxy formation Cosmology Initial conditions Structure formation Gas cooling Star formation Feedback Mergers Dynamical evolution Chemical evolution 2.3 Time scales 2.4 Some historical notes Contents

6 Before 1920s: nature of galaxies entirely unclear All within the Milky Way? Some island universes? 1755: Kant speculates about Weltinseln : Charles Messier lists 103 (later amended to 110) objects in his Catalogue of Nebulae and Star Clusters

7 Messier objects

8 Before 1920s: nature of galaxies entirely unclear All within the Milky Way? Some island universes? 1755: Kant speculates about Weltinseln : Charles Messier lists 103 (later amended to 110) objects in his Catalogue of Nebulae and Star Clusters Examples of data : drawings by Lord Rosse as seen through his 72 telescope in 1845:

9 Before 1920s: nature of galaxies entirely unclear All within the Milky Way? Some island universes? 1755: Kant speculates about Weltinseln : Charles Messier lists 103 (later amended to 110) objects in his Catalogue of Nebulae and Star Clusters 1864: Herschel s General Catalogue of Galaxies (5079 objects) 1888: Dreyer s New General Catalogue of Nebulae and Clusters of Stars, later supplemented by Index Catalogues (> 15,000 objects)

10 Andromeda (M31) around 1890

11 Before 1920s: nature of galaxies entirely unclear All within the Milky Way? Some island universes? 1755: Kant speculates about Weltinseln : Charles Messier lists 103 (later amended to 110) objects in his Catalogue of Nebulae and Star Clusters 1864: Herschel s General Catalogue of Galaxies (5079 objects) 1888: Dreyer s New General Catalogue of Nebulae and Clusters of Stars, later supplemented by Index Catalogues (> 15,000 objects) 1920: The Great Debate Harlow Shapley Heber Curtis

12 Before 1920s: nature of galaxies entirely unclear All within the Milky Way? Some island universes? 1755: Kant speculates about Weltinseln : Charles Messier lists 103 (later amended to 110) objects in his Catalogue of Nebulae and Star Clusters 1864: Herschel s General Catalogue of Galaxies (5079 objects) 1888: Dreyer s New General Catalogue of Nebulae and Clusters of Stars, later supplemented by Index Catalogues (> 15,000 objects) 1920: The Great Debate 1925: argument resolved by Hubble s observations of Cepheids in Andromeda Edwin Hubble

13 Distance measurements Cepheids = periodic variable stars with an empirical relationship between their period and luminosity (Henrietta Swan Leavitt, 1908) L P n, n Standard candle

14 Before 1920s: nature of galaxies entirely unclear All within the Milky Way? Some island universes? 1755: Kant speculates about Weltinseln : Charles Messier lists 103 (later amended to 110) objects in his Catalogue of Nebulae and Star Clusters 1864: Herschel s General Catalogue of Galaxies (5079 objects) 1888: Dreyer s New General Catalogue of Nebulae and Clusters of Stars, later supplemented by Index Catalogues (> 15,000 objects) 1920: The Great Debate 1925: argument resolved by Hubble s observations of Cepheids in Andromeda distance = 900,000 ly, far outside of MW (correct value: 2.5 x 10 6 ly) birth of extragalactic astronomy

15 1912: Vesto Slipher discovers the systematic redshift of the spectra of spiral nebulae 1929: Edwin Hubble combines Slipher s redshifts with his own distance measurements:

16 Fundamental observation: linear relationship between distance and recession velocity: v = H 0 d (Hubble s Law) Successfully interpreted in the context of Einstein s General Relativity (1915) as the expansion of the Universe Birth of modern cosmology

17 1946: prediction of Cosmic Microwave Background by Gamow (rediscovery of prediction in 1960s by Wilkinson, Peebles, Dicke) 1965: discovery of CMB by Penzias & Wilson

18 Holmdel, New Jersey

19 Penzias & Wilson (1965)

20 Arno Penzias und Robert Wilson Penzias & Wilson (1965)

21 1946: prediction of Cosmic Microwave Background by Gamow (rediscovery of prediction in 1960s by Wilkinson, Peebles, Dicke) 1965: discovery of CMB by Penzias & Wilson : discovery of CMB temperature fluctuations by COBE

22 Cosmic Microwave Background Explorer John Mather George Smoot

23 1946: prediction of Cosmic Microwave Background by Gamow (rediscovery of prediction in 1960s by Wilkinson, Peebles, Dicke) 1965: discovery of CMB by Penzias & Wilson : discovery of CMB temperature fluctuations by COBE : WMAP : Planck

24 1940s: first primordial nucleosynthesis calculations by Gamow 1957: B 2 FH paper on nucleosynthesis in stars 1967: Wagoner s explanation of the abundance of light elements by primordial nucleosynthesis

25 1940s: first primordial nucleosynthesis calculations by Gamow 1957: B 2 FH paper on nucleosynthesis in stars 1967: Wagoner s explanation of the abundance of light elements by primordial nucleosynthesis 1960s 70s: major cosmological problems: Flatness problem Horizon problem Origin of structure

26 1940s: first primordial nucleosynthesis calculations by Gamow 1957: B 2 FH paper on nucleosynthesis in stars 1967: Wagoner s explanation of the abundance of light elements by primordial nucleosynthesis 1960s 70s: major cosmological problems: Flatness problem Horizon problem Origin of structure 1981: extension of the classical cosmological standard model by Guth s inflationary theory Paul Steinhardt Andrei Linde Alan Guth

27 1960s: adiabatic vs isothermal initial perturbations? Harrison (1970) and Zel dovich (1972) work out the spectrum of initial density fluctuations (scale invariant) 1933: Zwicky points out the necessity of Dark Matter based on velocity dispersion of Coma Cluster Late 1970s: DM finally generally accepted Early 1980s: Hot Dark Matter (HDM) unlikely Rise of the CDM paradigm 1990s: difficulty to reconcile all cosmological observations (CMB, clustering of galaxies, abundance of galaxy clusters) with a flat CDM model

28 1998: discovery of the accelerated expansion of the Universe (Riess et al., Perlmutter et al.) Dark Energy Standard model of cosmology: CDM

29 1962: monolithic collapse model for elliptical galaxies by Eggen, Lynden-Bell & Sandage 1972: Toomre & Toomre suggest most ellipticals are the result of mergers Mid-1970s: first numerical simulations of galaxy formation by Larson, couldn t yet make ellitpticals Late 1970s: first simulations of mergers remnants similar to ellipticals : CfA redshift survey 1978: White & Rees first put together the basic elements of modern galaxy formation theory, including CDM 1980: discovery of morphology-density relation by Dressler 1990s: rise of CDM N-body simulations

30 1991: first semi-analytical CDM galaxy formation model by White & Frenk 2000: discovery of relation between central SMBH and host spheroid 2000: Sloan Digital Sky Survey (SDSS) begins rise of large-scale galaxy surveys 2013: hydrodynamical simulations in a cosmological context produce realistic galaxies

31 Galaxies from the Illustris simulation

32 1. Introduction 2. Overview of galaxies and physical processes 3. Cosmological background 4. Properties of galaxies: descriptions, observations and results 5. Formation of Dark Matter halos 6. Formation of gaseous halos 7. Star formation 8. Stellar and chemical evolution 9. Observing galaxies 10.Disk galaxies 11.Elliptical galaxies 12.Active galaxies 13.Clusters of galaxies 14.Intergalactic medium Contents