
Course unit
OBSERVATIONAL COSMOLOGY
SCP9086346, A.A. 2019/20
Information concerning the students who enrolled in A.Y. 2019/20
ECTS: details
Type 
ScientificDisciplinary Sector 
Credits allocated 
Core courses 
FIS/05 
Astronomy and Astrophysics 
6.0 
Course unit organization
Period 
Second semester 
Year 
1st Year 
Teaching method 
frontal 
Type of hours 
Credits 
Teaching hours 
Hours of Individual study 
Shifts 
Lecture 
6.0 
48 
102.0 
No turn 
Prerequisites:

The course is selfconsistent, having acquired the whole fundamental notions of mathematics and physics of the 3year degrees in Astronomy or Physics. 
Target skills and knowledge:

The course describes the general structure and evolutionary history of the universe and its components, dark matter and energy, baryonic matter, radiative components. The main evolutionary phases and structures (large scale structure of dark matter, evolutionary history of baryons) are discussed.
The main observables and observational procedures needed to achieve the results are particularly discussed. 
Examination methods:

Oral discussion 
Assessment criteria:

We require some understanding of the fundamental physical concepts concerning the themes of the course. Mathematical derivations are optional (though sometimes useful to reconstruct a process).
The student should synthetically demonstrate an understanding of the main observational approaches to achieve a result. 
Course unit contents:

1) The homogeneous and isotropic (Friedmann) Universe: Hubble law. The Cosmological Principle. Isotropic curved spaces. The RobertsonWalker metric. Cosmic dynamics, the Newtonian and generalrelativistic approach. Cosmological models and parameters. Fundamental observables. The redshift. Luminosity and angular diameter distances. Timeredshift relations. Hubble diagrams. Generalized dynamical equations. The cosmological constant.
2) The large scale structure of the Universe: Local properties. Angular and spatial correlation functions. Higher order correlations. Limber relation. Powerspectrum of the cosmic structures. Relationship of the powerspectrum and ΞΎ(r). Observational data on the large scale structure. The initial powerspectrum of the perturbations. 3D mapping of galaxies, clusters, AGNs. Countsincells. Outline of fractal and topological analyses of the largescale structure of the universe.
2) Deviations from homogeneity: Gravitational lensing. Pointlike lenses and isothermal spherical distributions. Lens potentials. Einstein radius. Lensing cross sections. Lensing effects on time lags. Caustics. Observations of the gravitational lensing and cosmological applications. Estimate of the total galaxy cluster mass. Estimates of H0. Effects of a cosmological constant L in the lensing statistics. Micro lensing and weaklensing. Mapping of the mass distribution.
3) Cosmological evolution of perturbations in the cosmic fluid: Cosmological evolution of perturbations in the thermodynamical parameters of the various components of the cosmic fluid. General equations in a static universe and in an expanding one. Evolution in a matter dominated universe. Hubble drag. Relationship of perturbations and velocity fields.
4) Perturbations in an expanding universe: Peculiar motions of galaxies and structures. Deviations from the Hubble flow, peculiar velocity fields in the cosmos. Observations of peculiar velocity fields. The cosmic viral theorem. Origin of the large scale motions.
5) Brief thermal history of the Universe: The matter and radiation content of the Universe. Energy densities and their evolution. Radiationdominated universes. The epochs of recombination and equivalence. Primordial nucleosynthesis and its consequencies.
6) The Cosmic Microwave Background (CMB): Discovery, observations from ground and from space. Origin of the CMB. Statistical description of the angular structure. Origin of the CMB angular fluctuations. Physical processes in operation on the large scales. Fluctuations on intermediate angular scales. Contributions of sources to the anisotropies on small scales. Cosmological reionization and its impact on CMB. Constraints of CMB observations on the cosmological parameters. The CMB spectrum, spectral distorsions. The SunyaevZeldovich effect. Polarization.
7) The primordial Universe: Big Bang singularity. Planck time. Propagation of the information in the universe. Cosmological phase transitions. Open questions about the standard Big Bang model. The horizon problem. The flatness problem. Cosmological inflation and solutions to the problems. The Anthropic Principle.
8) Origin and evolution of the cosmological structure: Generation of the perturbation field. General composition of the cosmic fluid: the dark matter, cold and hot dark matter. Stagnation of the dark matter perturbation before the equivalence. Transfer function. Nonlinear evolution. The PressSchechter theory.
9) Postrecombination universe. Intergalactic diffuse gas. Absorptionlines in quasar spectra, Lymanalpha clouds. The missing baryon problem. Evolutionary history of star formation and black hole accretion in quasars. Origin of the galaxy mass function. 
Planned learning activities and teaching methods:

Lectures and exercises given in Italian. 
Additional notes about suggested reading:

Lecture notes by the teacher and textbooks. Lecture notes will be provided at the beginning of the course. 
Textbooks (and optional supplementary readings) 

Longair, Malcolm S., Galaxy Formation. Berlin: Springer, 2008.

Schneider, Peter, Extragalactic Astronomy and Cosmology. Heidelberg: Springer, 2015.

Peacock, John A., Cosmological Physics. Cambridge: Cambridge University Press, 2010.


