HIGH ENERGY ASTROPHYSICS

Il corso mira ad offrire una introudzione di base alla Fisica degli Oggetti Compatti e alle loro evidenze sperimentali (osservative). Dopo aver seguito il corso lo studente avrà acquisito un insieme di strumenti teorici e fenomenologici di base che gli permetteranno di collocare la Fisica degli Oggetti Compatti nel più ampio contesto dell'evoluzione galattica nell'Universo, e delle loro reciproche relazioni.

Particolare attenzione verrà ricolta a due aspetti metodologici:

• L'evidenza osservativa degli Oggetti Compatti su tutto lo spettro elettromagnetico, dal dominio radio alla radiazione gamma e ai raggi cosmici e neutrii di alta energia;
• Modellizzazione degli Oggetti Compatti e delle loro reciproche interazioni con le popolazioni stellari delle galassie che li ospitano.

Le Esercitazioni costituiranno parte integrale del cosrso, e metteranno gli studenti nella condizione di poter effettuare un' autovalutazione dei loro progressi nell'apprendimento.

Ventuno lezioni frontali di due ore ciascuna.

Relatività ristretta: Cinematica (trasformazioni di Lorentz), principio di covarianza.

Nozioni fondamentali sui fenomeni radiativi: emissione di sincrotrone, radiazione di frenamento (Brehmsstrahlung), interazioni fotone-particlelle (effetto Compton, diretto e inverso).

Frequenza non obbligatoria.

The course is divided into four parts:

1) Compact Objects: Observational evidence

Stellar-sized compact objects: White Dwarfs, Neutron stars, Black Holes (semi-classical). Final phases of stellar evolution: supernovae and gravitational collapse. Thermal instability. "Fireballs" and jets. Shock wave propagation. Mass spectrum of Supernova remants and emerging stellar BHs.
Supermassive BHs: observational evidence. BH-galaxy scaling relations (local Universe). Self-similar BH-galaxy co-evolution. Self-similarity breaking scales: environmental effects.

2) Active Galactic Nuclei and their host galaxies

AGNs: spectral properties. Quasar, Seyfert Galaxies: optical and UV spectral properties. Broad Absorption Line region (BAL): absorption and emission line formation. BAL: modelling. BAL: diagnostics of accretion region. Fanaroff-Riley galaxies: radio modelling.Stellar evolution (reminder). Off-Main Sequence stellar tracks, Red Giant Brach (RGB). Post-AGB stars. Dust formation. Stellar formation in galaxies. Stellar population synthesis modelling. Ages of stellar populations in high redshift galaxies.Cosmological evolution of AGN populations. AGNs and stellar formation. Galaxy evolution in colour diagrams. Main sequence of galaxies (MSG). Evolution off-MSG: Blue Cloud, Green Valley, Red Sequence: physical interpretation. Madau diagrams. AGN feedback: Introduction. Dynamical evolution of jet-ISM interactions. Radio cocoon and radio jets: synchrotron emission and modelling.

3) Black Holes: A physical introduction​.

Parallel transport in curved Space-Time. Geodesics: definition and general properties. Killing vectors and symmetries. Riemannian (intrinsic) curvature of ST. Einstein equations.
Static (Schwarzschild) and rotating (Kerr-Newman) BHs. Geodesics around BHs. Post-newtonian and PPN solutions. Horizon. BH membrane model. Wormholes: basic properties. Approximated gravitational potential: Paczinsky-Wijta and their extensions.
Accretion discs around BHs. Shakura-Sunyaev, slim discs. Magnetic fields around BHs magnetospheres. Relativistic jets: formation and structure. Spectra of accretion discs and jets. Sites of UHECRs and neutrinos production and acceleration.
Gravitational waves from binary BHs: generation. Waveforms and BH binary parameters estimation. GWs scattering (short introduction). GW background: probe of galaxies cosmological evolution. "Multimessenger" astrophysics through GW and neutrinos backgrounds.

4) High-energy particle acceleration and BHs

Magnetic fields around accretion discs and jets. Sites of MF acceleration. Fermi I and II mechanisms. Pair annihilation. Neutrino production from in-site hadronic interactions. Detailed balance (equilibrium). Non-equilibrium particle production (short introduction). Charged particle propagation: Greisen-Zatsepin-Kuzmin distance. Ultra-High Energy Cosmic Rays and neutrinos: production mechanisms.

1. P. Schneider - Extragalactic Astronomy and Cosmology - An Introduction, Springer V. (New York) (2006)
2. S. Shapiro, S. Teukolsky - Black Holes, White Dwarfs and Neutron Stars - The Physics of Compact Objects, Wiley & Sons (2008)
3. J. Krolik - Active Galactic Nuclei: From the Central Black Hole to the Galactic Environment, Princeton University Press (1999)
4. G. Ghisellini - Radiative Processes in High Energy Astrophysics, Springer V. (New York) (2013)
5. R. D'Inverno - Introducing Einstein's Relativity, Oxford University Press (2013)
6. M. Bartelmann - Theoretical Astrophysics: An Introduction, Wiley & Sons (2013)

Written part: 4 problems (one for each of the four parts of the course).

Not applicable to this course (yet).