SEMINAR IN EXTRAGALACTIC AST
SEMINAR IN EXTRAGALACTIC AST AST 386S
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This 8 page Class Notes was uploaded by Keegan Goyette on Sunday September 6, 2015. The Class Notes belongs to AST 386S at University of Texas at Austin taught by Staff in Fall. Since its upload, it has received 23 views. For similar materials see /class/181764/ast-386s-university-of-texas-at-austin in Astronomy at University of Texas at Austin.
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Date Created: 09/06/15
ASTRONOMY 386C GALAXIES Note 7 This is a draft syllabus based my previous Galazries course Most but probably not all of the material is likely to be covered I will be bringing the course content more up to date 1 MORPHOLOGY 11 Galaxy Classi cation Schemes The Hubble system The de Vaucouleurs system The Morgan system cD galaxies Luminosity classi cation 12 Quantitative Morphology Correlation of physical parameters With Hubble types 13 Physical Morphology Galaxy components Oval disks Flocculent versus global spiral structure 2 LUMINOSITY FUNCTIONS Definitions The Schechter function Observations of the field galaxy luminosity function Cluster luminosity functions Luminosity functions for different Hubble types The mix of different Hubble types morphology density relation Fraction of all light from bulge E and disk components 3 ELLIPSOIDS BULGES ELLIPTICAL GALAXIES AND GLOBULAR CLUSTERS 31 Surface Photometry Review of techniques photographic CDD Radial brightness profiles 0 Systematics o Analytic fitting functions cD galaxies properties of cD halos Cores ground based and HST observations 32 Families of Ellipsoidal Stellar Systems Global and core parameter correlations Three kinds of stellar systems bulges ellipticals Sphs globulars Relationship between Sph and S 1 galaxies lntroduction 33 The Fundamental Plane of Elliptical Galaxies Global and core parameter correlations Scalar virial theorem derivation of the fundamental plane equations Implications for galaxy formation MLL 34 Stellar Dynamics Observations Measurement techniques 0 cross correlation Fourier quotient Fourier correlation quotient Line of sight velocity distributions LOSVDs Observations of rotation and velocity dispersion profiles Velocity anisotropy the VO39 7 E diagram Observational confirmtaion of triaxiality and anisotropy o Minor axis rotation o Shapes of E galaxies statistics of apparent shapes 0 lsophote tWists 0 Dust rings implications for E shapes 35 lsophote Shapes Boxy and Disky Es Measurements of isophote shapes a4a Correlations of a4a With physical properties Physical dichotomy of E galaxies into 0 l High L nonrotating boxy anisotropic Es With cuspy cores and o 2 Medium and low L rotating disky approximately isotropic and coreless Es Proposed revision of the Hubble sequence boxy E 7 disky E 7 S0 7 Sa 7 Sb 7 Sc 7 Exceptions Boxy bulges and low L boxy Es origin 7lm 36 Collisionless Dynamics Theory Stellar systems are fundamentally more complicated than gases 0 Long mean free path Characteristic times crossing time relaxation time Distribution function Fundamental equations of macroscopic stellar dynamics 0 Collisionless Boltzmann equation 0 Poisson equation First moment equations basic equations of stellar hydrodynamics o The Jeans equations Second moment equations tensor virial theorem Application to VO39 7 E diagram anisotropy 37 Galaxy Models l f fELZ Jeans Theorem Models With f fE polytropes isothermals King models 0 Emphasize similarities between stellar dynamical and gas case i e stars 0 i 02 kTm 0 Core mass to light ratios Models With f fELZ 38 Globular Cluster Observations and Models Density distributions Velocity dispersion profiles Models With a range of stellar masses m 39 Stellar Orbits in Ellipsoidal Stellar Systems Orbits in a spherical potential Orbits in axisymmetric potentials classical integrals Orbits in triaxial potentials 310 Galaxy Models 11 Galaxy E weighti orbitZ Schwarzschild7s method examples Spherical maximum entropy models examples Axisymmetric maximum entropy models examples 311 Dynamical Evolution of Ellipticals and Globular Clusters Theory Phase mixing and violent relaxation 0 Origin of the p olt r14 density distribution Two body encounters and relaxation 0 Heat capacity of a self gravitating stellar system is negative Gore collapse single 771 simulations Stopping core collapse via binaries Gravothermal oscillations Complications range of 771 primordial binaries stellar evolution physical stellar collisions stellar coalescence runaway stellar mergers External in uences o Tidal effects 0 Disruption of globular clusters by galactic disk shocking 0 Relation between present and primordial globular cluster population 312 Dynamical Evolution of Ellipticals and Globular Clusters Observations Post core collapse density distributions in globulars Mass segregation Stellar population gradients blue stragglers Stellar population gradients in bulges and Es effects of high stellar density 313 Supermassive Black Holes BHs in Galactic Nuclei Brief motivation nucelar activity see 9 Origin of seed BHs via evolution of dense stellar systems Stellar dynamical search for BHs Gas dynamical search for BHs BH demographics Flashes When stars are accreted by BHs 4 DISK GALAXIES 41 Surface Photometry Radial brightness pro les of bulges and disks 0 Analytic tting functions Disk parameter corrrelations Bulge disk decomposition Vertical brightness profiles of disks 0 Analytic tting functions Thick disks 42 Bulge Dynamics Evidence that some bulges are really disks Revised bulge to total luminosity ratios as function of Hubble type 43 Vertical Structure of Thin Disks Theory The isothermal sheet 44 Local Stability of Disks Jeans instability velocity dispersion stabilizes small scale perturbations Rotation stabilizes large scale perturbations Complete stability Toomre7s Q parameter Observations Q in the Galactic solar neighborhood Observations Q in other galaxy disks Other disk heating mechanisms 0 Lumps the Spitzer Schwarzschild mechanism 0 Scattering by bars and spiral structure 0 Heating by accreted satellites 45 Spiral Structure Observations of global spiral structure Epicyclic theory Kinematic spiral density waves Dynamical spiral density waves Swing amplification Observational consequences and tests Alternatives 0 Self propagating star formation and occulent spirals o Tidal spirals 46 Bars Observed properties of SB galaxies bars rings and lenses Formation and evolution of bars n body simulations Importance of bars secular evolution 0 Orbits in barred potentials 0 Radial transport of gas star formation 0 Stellar dynamical secular evolution density redistribution angular momentum transport 0 Formation or box shaped bulges and lenses 47 Kinematics of the Galactic Solar Neighborhood Standards of rest Effects of galactic rotation o lntuitive picture 0 Global formulae 0 Local approximations Random velocities in the solar neighborhood velocity ellipsoid Asymmetric drift 48 Global Structure of the Galaxy The Hubble type of the Galaxy Galactic parameters Thin disk Population I Stellar halo Population ll Thick disk lntermediate Population ll Evidence that the Galaxy is barred 49 Warps in Galaxy Disks Observations mostly Hl The problem formation and maintenance of warps The solution triaxial dark halos 5 STELLAR POPULATIONS IN GALAXIES 51 Stellar Populations at z 2 0 History of the discovery of stellar populations in the Galaxy Observations of disks Star formation history of disks Observations of elliptical galaxies 0 Color and line strength gradients o Degeneracy between metallicity and age 0 Current problems evidence that low L Es have a variety of ages 52 Stellar populations in high redshift ellipticals Line strengths and fundamental plane correlations as function of z 0 Evidence that giant ellipticals are old Star formation history of ellipticals 6 DWARF GALAXIES 61 Introduction Importance of low L galaxies The fundamental observed property of low L galaxies is low baryon density The fundamental theoretical explanation is baryonic blowout by winds lmplication dwarf galaxies have an unusually large dark matter fraction 62 Observed properties of low L and low surface brightness galaxies Fundamental plane parameter correlations Selection effects implications for correlations L function lcebergs and crouching giants Malin l and relatives 63 Galaxy Formation l Low Luminosity Galaxies Baryonic blowout via galactic winds 0 Recall similarity of dwarf S l and dSph galaxies o Saito Dekel Silk mechanism blowout of baryons by galactic winds 0 Expansion of a stellar system after mass loss 0 Observational evidence for mass loss via galactic winds 0 Stochastic starbursts in dwarf galaxies Ram pressure stripping 0 Evidence for and against Other processes revival of dl galaxies by gas accretion Bombproof evidence that dl galaxies evolve into dSphs o The age distribution of stars in dSph galaxies 7 DARK MATTER 71 Historical lntroduction Dark matter in the Galactic disk Oort Dark matter in the Coma cluster Zwicky Stability of cold disks versus bars Ostriker amp Peebles 72 Observational Evidence for Dark Matter Hl rotation curves Velocity dispersions in dSph galaxies Satellites of our Galaxy X ray gas in galaxies and clusters hydrostatic equilibrium of a hot gas Velocity dispersions of clusters of galaxies Gravitational lenses Large scale velocity fields 73 Regularities in DM Halo Properties Conspiracy between luminous and dark matter to make at V0 Parameter correlations Rotation curve decomposition into visible and dark matter components Fundamental plane for dark matter halos Evidence for baryonic compression of dark matter halos Implications for galaxy formation 74 What is Dark Matter MOND Modified Newtonian Dynamics Disk dark matter is baryonic it dissipated Primordial nucleosynthesis constraints on baryonic dark matter Baryonic halos 0 Things that won7t work snowballs M dwarfs white dwarfs neutron stars 0 Things that might work brown dwarfs black holes of mass 105i1 9 Gravitational microlensing surveys Hot warm and cold elementary particles Constraints on neutrino dark matter from dwarf galaxies Direct detection of particle dark matter 8 GALAXY FORMATION Note The origin and early evolution offluctuations belongs in the Cosmology course Some discussion of hierarchical clustering and the formation of large scale structure is inevitable here because the study of galaxy formation cannot be removed from its cosmological contezrt Basically the aim here is to discuss galazry formation starting at a time when individual objects are well separated from the ezrpansion of the universe 81 Introduction Eggen Lynden Bell amp Sandage 1962 Hydrodynamic collapse simulations 82 Galaxy Mergers Theory Dynamical friction and orbital decay Chandrasekhar7s formula lmplications o Toomre7s hypothesis that all bulges and ellipticals are merger remnants 0 Galaxy formation must be studied in the context of large scale structure formation Conservation of phase space density 83 Simulations of Hierarchical Clustering and Galaxy Formation Cold dark matter simulations 0 Properties of the galaxies that form 0 Comparison with observations successes and failures Dissipationless simulations of group and binary mergers 0 Properties of the galaxies that form 0 Comparison with observations successes and failures The need for dissipation Dissipational simulations of group and binary mergers 0 Properties of the galaxies that form 0 Comparison with observations successes and failures 84 Observational Constraints on Galaxy Formation Observations of mergers in progress 0 Merger sequence from close binary galaxies a violence a remnants Starbursts IRAS galaxies Possible connection between ultraluminous IRAS galaxies and quasars Recognizing old mergers tails shells and other fine structure Recognizing completed mergers embedded stellar disks 0 Photometric signatures o Kinematic signatures Small accretion events 0 Not every elliptical with fine structure needs to be a major merger remnant 85 Tentative Verdict Mergers uersus Dissipative Collapse Strengths and weaknesses of the merger picture Evidence from high z galaxies Bottom line both mergers and dissipative collapse were important 86 Physical Processes During Galaxy Formation Origin of the Fundamental Plane Dissipation cooling times and galactic scales Complications energy input during starbursts etc Formation of ellipticals Rotation of disk galaxies Late infall of cold gas Ongoing problems Connections With observations at high 2 9 ACTIVE GALACTIC NUCLEI l Taxonomy Radio galaxies Quasars and BL Lac objects Seyfert l galaxies Seyfert 2 galaxies LlNERs 92 Demographics Number densities compared to galaxy densities Evidence for evolution Peak in quasar densities at z 2 2 7 3 93 Emission Line Physics Hydrogen spectrum Forbidden lines Models of the broad and narrow line regions 94 Continuum Radiation Thermal components dust scattering Nonthermal radiation synchrotron radiation Jets properties relativistic beaming Gamma rays 95 The Unified Model of Nuclear Activity in Galaxies 96 Power Sources Starbursts pro and con Black holes pro and con The critical observations that imply black hole engines The Galactic center
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