Academic Year 2020/2021 - 2° Year - Curriculum ASTROPHYSICS
Teaching Staff: Antonino DEL POPOLO
Credit Value: 6
Scientific field: FIS/05 - Astronomy and astrophysics
Taught classes: 42 hours
Term / Semester:

Learning Objectives

EXTRA-GALACTIC ASTRONOMY AND COSMOLOGY is a course of the Master's degree in Physics designed to provide an introduction to extra-galactic astronomy and cosmology.
The course provides a background of extragalactic astronomy and modern cosmology. After an overview of the properties of galaxies, clusters, large-scale structure of the universe, the course will present a description of Newtonian and relativistic cosmology, and structure formation in a rapidly expanding universe (dominated by matter and dark energy).

Course Structure

A. Extragalactic Astronomy

B. Introduction to Cosmology

Detailed Course Content

1. Galaxies, Generalities
Shapley-Curtis Debate. Classification of galaxies.
Hubble's fork diagram. Variation of the physical characteristics of the galaxies in the Hubble diagram. Comb classification (Atlas3D).

Properties of spiral galaxies. Correction K and of the brightness of the background. Profile of Sersic and de Vacouleurs. Rotation curves. Dark matter. Virial theorem and applications. Tully Fisher relationship. Radius-luminosity relationship, masses, M / L ratio, colors and abundance of gas and dust, gradients of metallicity and colors in spirals. BH mass relation and velocity dispersion. Globular cluster frequency. Spiral structure and Lin-Shu theory.

Elliptical galaxies: morphology, scale relationships (Faber-Jackson relationship, Fundamental Plan). Colors and abundance of gas and dust, gradients of metallicity and colors in ellipticals. Effects of the presence and absence of rotation

2. Formation, Dynamics and galactic evolution

Non-collisional systems and relaxation time. The distribution function. Boltzman and Jeans equation. Examples: isothermal sphere. Density, mass, velocity from photometry. Gravitational potential of simple systems.

Galactic evolution: Interaction between galaxies: evidence of interactions. Dynamic friction. High speed encounters; approximation of the impulse. Simulations of interactions. Galaxy Starbursts. Mergers in ellipticals and cD galaxies.

Merger of black holes. Galactic formation: ELS model. Problems with the ELS model. Problem of the G-dwarfs. Dissipative collapse model.

Model of hierarchical formation. MW formation in the hierarchical model. Formation of elliptical galaxies. Galactic formation in the primordial universe. Morphology-distance relationship, Butcher-Oemler effect.
Formation of structures in the ΛCDM model. Brief history of the universe. Density perturbations. Linear and non-linear growth of perturbations. Problems of the ΛCDM model (galaxy down-sizing; cusp-core problem; missing satellite problem; too-big-to-fail problem). Feedback from SN and AGN.

3. Active galactic nuclei. Seyfert Galaxies. Spectrum of AGN. Emission X, thermal (IR), radio (synchrotron radiation). Quasars: discovery, luminosity.

Spectrum of the quasars. QSRs and QSOs. ULIRGs. Evolution of quasars. Varability, polarization of emission, FRIe FRII classes. Blazars, LINERs. Radio galaxies: structure, lobes, jets, superluminal motions. Unified model of quasars: the nature of the central engine, energy production, accretion and luminosity, structure of the accretion disk, generation of the jets (Blandford-Znajek maccanism, broad and wide line regions). Radio lobes and jets: formation of jets and of the lobes, acceleration of the particles, acceleration of the particles in the jets, superluminal velocity, model of Rees, one sided jets and relativistic effects, evolution of the AGNs, quasars as probes of the universe Lensing, Lyman α Forest.

4. Black holes
Equivalence principle and GR. Tests of the GR. Stellar, intermediate and supermassive black holes. Black holes in GR. Schwarzschild and Kerr geometry. Orbits and stability. Observable effects. Quantum gravity and Hawking radiation. Evidence of the existence of BHs. Stellar dynamics and motions of test particles (eg, Star S2). Megamasers of H2O. Dynamics of gas ..

5. The comological ladder and its steps.
Historical outline of the distances and dimensions of the solar system objects (Rung 1: Earth; Rung 2: Moon; Rung 3: Sun; Rung 4: the planets; Rung 5: velocity of light; Rung 6: neighboring stars: parallax, statistical and secular parallax, Rung 7: intermediate distance stars: spectroscopic parallaxes (main sequence fitting) Rung 8: distant stars: Cepheids, Wilson-Bappu effect, supernovae-based methods, Novae Secondary indicators: Globular clusters, Planetary nebulae; HII regions, surface brightness fluctuation method; Tully-Fisher; Faber-Jackson; D-σ; brightest galaxies in a cluster; Rung 9: Hubble law, Hubble constant and its value. Expansion of the universe and Hubble flow: cosmological redshift vs. doppler.

6. Large-scale structure
Hierarchy of cosmic structures. Clusters: classification and examples (Virgo and Coma clusters). Plasma in clusters. Bremsstrahlung. Hydrostatic equilibrium and mass Substructure, Sunnyaev-Zeldovich effect. Viral mass and DM Local group and other groups in 10 Mpcs. Large scale, peculiar velocities, CMBR dipole, infall to Virgo and motions to Hidra-Centaurus, and Shapley's concenration. Great attractor. Redshif surveys (2dF; SDSS; CfA). Superclusters: the local cluster, supercluster and neighboring superclusters. Structure of LSS (clusters, superclusters, voids, filaments). LSS quantification methods: two-point correlation function, spectrum. Galaxy biasing, clustering evolution.

7. Newtonian Cosmology

The paradox of Olbers. The cosmological principle. Model of dust universes (without pressure) and evolution. Age of a universe of dust. Lookback time. Extension of the dust model to include pressure. Background microwave radiation (CMB). Steady state theory. Cooling of the universe after the Big Bang. Discovery of the CMB. Dipole anisotropy of the CMB. Sunyaev-Zel'dovich effect. Sachs-Wolfe effect. Cosmic harmonics and acoustic oscillations. A simple model of acoustic oscillations. TT spectrum of the CMB. Polarization of the CMB. BAOs. Universe with two material components: matter (baryons and DM), relativistic particles. Decoupling of neutrinos. Density of energy of relativistic particles. Transition from the era of radiation to the era of matter. Evolution of the two-component model. Nucluosynthesis and CMB origin. Surface of last scattering.

8. Relativistic Cosmology

Euclidean, elliptic and hyperbolic geometry. Robertson-Walker metric. Friedman equations. The cosmological constant and dark energy. The era of Λ. Observational Cosmology. The origin of the cosmological redshift. Distance of remote objects in the universe. Particle orizon and distance horizon. Time of arrival of photons. Maximum age of a visible source. Comoving coordinates. Proper distance and brightness. Redshift- magnitude relationship. Angular diameter distance

The primordial Universe
Very early universe and inflation. HDM and CDM. Planck scale of masses, times and distances. Unification and spontaneous symmetry breaking. Problems of the standard Big Bang theory. Virtual particles and vacuum energy. Problem of the cosmological constant. Solutions to the problems of the standard Big Bang theory. Asymmetry antimatter, matter. CMB and the decoupling of matter and radiation. Origin of cosmic structures. Adiabatic and isothermal density fluctuations. Mass of Jeans in various cosmological epochs. Acoustic oscillations and their damping. Timing of the formation of the structures. Top down and bottom up models of structure formation.

Textbook Information

Reference texts
Bradley W. Carrol, Dale A. Ostlie, An Introduction to Modern Astrophysics
P. Schneider, Extragalactic Astronomy and Cosmology. An Introduction (Springer)
M. Longair, Galaxy Formation (Springer)
M. Roos, Introduction to Cosmology, third edition
J. V. Narlikar, An Introduction to Cosmology 3rd Edition