96382 - Active Galactic Nuclei and Supermassive Black Holes

Learning outcomes

At the end of the course, the student will have a good knowledge of the observational and physical properties of Active Galaxies in the various bands of the electromagnetic spectrum and their cosmic evolution. The first black hole in the Universe will be discussed along with their growth history and active phases. Knowledge of the strict link between the accretion processes of supermassive black holes at the center of galaxies and star-formation activity, in the so-called co-evolution scenario involving feedback processes, will also be acquired by students.

Course contents

Main topics: AGN physics and classification - AGN evolution - The first AGN in the Universe. AGN feedback.

• Introduction to the course.

1. Brief historical and physical perspective on AGN.
2. Pills on radiative transfer and on thermal and non-thermal processes.
3. AGN classification and unification model.
4. AGN broad-band and X-ray emission: observations, physical processes, and models.
5. Jetted vs. not-jetted AGN. Emission processes, observational features, spectral energy distributions, and blazar sequence. Prospects for the Cerenkov Telescope Array.
6. On the nature of obscuration in AGN: torus vs. host galaxy. Photometric and spectroscopic selection techniques of obscured AGN.
7. The black hole paradigm. Radiatively efficient (Shakura-Sunyaev) accretion discs vs. ADAF solutions. Slim discs and their potential application to growing BHs.
8. A close look at the innermost regions of AGN: EHT and GRAVITY results.
9. The Galactic Center: SgrA* and its accretion history up the recent flares. The Galactic Plane: Fermi bubbles and X-ray chimneys.
10. AGN-galaxy co-evolution models. X-ray surveys and the cosmic X-ray background. Soltan argument.
11. The realm of high-redshift AGN. Theories of seed black holes. The JWST view of accretion at high redshift.
12. BH masses from reverberation studies and scaling relations.
13. Feedback (radiative/mechanic) from AGN. The impact of winds and outflows on small and large scales in setting the M-sigma relation. Recent multi-wavelength studies.
14. The role of mergers in triggering nuclear activity. The quest for dual/binary AGN in the era of gravitational waves.

Readings/Bibliography

Besides the slides of the lessons, some textbooks and relevant (review) articles are suggested to have an in-depth and updated study of the topics covered by this course. No need to read all of them. Students may decide to select the topic for the oral exam among the papers reported below [topic #, where # is related to the numbered list shown in Course Contents].

Textbooks

EMISSION PROCESSES [topic 2]

• H. Bradt: "Astrophysics Processes: The Physics Of Astronomical Phenomena", Cambridge University Press (CUP)
• G. B. Rybicky, A. P. Lightman: "Radiative Processes in Astrophysics", Wiley
• G. Ghisellini: "Radiative processes in high energy astrophysics", Springer, Lecture Notes in Physics 873

AGN PROPERTIES AND CLASSIFICATION [topics 1 to 7, 10 to 13]

• B. M. Peterson: "An introduction to Active Galactic Nuclei", CUP
  H. Netzer: "The Physics and Evolution of Active Galactic Nuclei", CUP
• V. Beckmann, C. Shrader: "Active Galactic Nuclei", Wiley-VCH
• A. King: “Supermassive Black Holes”
  

ACCRETION-DISC PHYSICS [topic 7]

• Frank J., King A. & Raine D.: "Accretion Power in Astrophysics", CUP
  
  

Relevant (review): some suggestions

Topic 3

• H. Netzer: "Revisiting the Unified Model of Active Galactic Nuclei", ARA&A, 53, 365 (2015)
• P. Padovani et al.: "Active galactic nuclei: what's in a name?", Astron. Astrophys. Rev., 25, 2 (2017).
  

Topic 4

• W. Alston, M. Giustini, P.-O. Petrucci: "The Super-Massive Black Hole close environment in Active Galactic Nuclei", Handbook of X-ray and Gamma-ray Astrophysics (Eds. C. Bambi and A. Santangelo, Springer; arXiv:2206.11790) (2022).

Topic 5

• R. Blandford, D. Meier, A. Readhead: "Relativistic jets from Active Galactic Nuclei", ARA&A, 57, 467 (2019).

Topic 6

• C. R. Almeida, C. Ricci: "Nuclear obscuration in active galactic nuclei", Nature Astronomy 1, 679 (2017);
• R.C. Hyckox, D.M. Alexander: "Obscured Active Galactic Nuclei", ARA&A, 56, 625 (2018).
  

Topic 7

• N.I. Shakura, R.A. Sunyaev: "Black Holes in Binary Systems. Observational appearance", A&A, 24, 337 (1973);
• A. King: "Disc accretion in active galactic nuclei", New Astronomy Reviews, 52, 253 (2008).

Topic 8

• The Event Horizon Telescope Collaboration: "First M87 Event Horizon Telescope results. I. The shadow of the supermassive black hole", ApJ, 875, L1 (2019).

Topic 9

• G. Ponti, M.R. Morris, R. Terrier, A. Goldwurn: "Traces of past activity in the Galactic Center", arXiv:1210.3034 (2012);
• A. Bryant, A. Krabbe: “The episodic and multiscale Galactic Centre”, New Astronomy Reviews, 93, 101630 (2021).

Topic 10

• B. Peterson: "The central black hole and relationships with the host galaxy", New Astronomy Reviews, 52, 240 (2008);
• A. King: "The supermassive black-hole - galaxy connection", Space Science Reviews, 183, 427 (2013)
• P.R. Capelo, C. Feruglio, R.C. Hickox, F. Tombesi: "Black hole-galaxy co-evolution and the role of feedback", Handbook of X-ray and Gamma-ray Astrophysics (Eds. C. Bambi and A. Santangelo, Springer; arXiv:2211.00765) (2022);
• W.N. Brandt, G. Yang: "Surveys of the Cosmic X-ray Background", Handbook of X-ray and Gamma-ray Astrophysics (Eds. C. Bambi and A. Santangelo, Springer; arXiv:2111.01156) (2022);
• D. M. Alexander et al.: “What drives the growth of black holes: a decade of progress”, New Astronomy Reviews, in press (arXiv:2506.19166) (2025).

Topic 11

• K. Inayoshi, E. Visbal, Z. Haiman: "The Assembly of the First Black Holes", ARA&A, 58, 27 (2020).
• E. Lusso, R. Valiante, F. Vito: "The dawn of black holes", Handbook of X-ray and Gamma-ray Astrophysics (Eds. C. Bambi and A. Santangelo, Springer; arXiv:2205.15349) (2022).

Topic 12

• Y. Shen: "The mass of quasars", Bulletin of the Astronomical Society of India, 41, 61 (2013).

Topic 13

• A.C. Fabian: "Observational evidence of active galactic nuclei feedback", ARA&A, 50, 455 (2012);
• A. King & K. Pounds: "Powerful Outflows and Feedback from Active Galactic Nuclei", ARA&A, 53, 115 (2015);
• C.M. Harrison, C.R. Almeida: "Observational Tests of Active Galactic Nuclei Feedback: An Overview of Approaches and Interpretation", Galaxies, 12, 17 (2024).

Topic 14

• A. De Rosa, C. Vignali, T. Bogdanovic et al.: "The quest for dual and binary supermassive black holes: A multi-messenger view", New Astronomy Reviews, 86, 102525 (2019).

Teaching methods

During lessons (all in person), carried out mostly using PowerPoint presentations (available on Virtuale), some of the most fundamental topics of modern astrophysics in the field of AGN and SMBHs, will be discussed, and the state-of-the-art framework will be presented. Students are encouraged to delve deeper into the topics faced in the course by carefully reading some selected chapters from recommended textbooks and recent publications, to gain a more up-to-date overview of the course's scientific topic

Assessment methods

Student's knowledge in the field of Active Galaxies and Supermassive Black Holes will be assessed through an oral exam on the dashboard, starting with a topic chosen by the student. This part consists of the presentation (about 30 minutes) of an article from those listed in the Readings/Bibliography sectionaboveor any other specific topic covered during class, followed by two to three questions on different subjects (for an additional 30 minutes). The student is expected to professionally connect the various topics covered during the course and critically discuss the state of the art in the field of AGN and supermassive black holes and related open questions. Furthermore, the student must demonstrate the ability to derive physical quantities on the dashboard (with appropriate units).

Final marks are assigned according to this scale:

• Limited preparation, in terms of the student's ability to answer questions independently (i.e., without guidance and suggestions by the professor) and the number of topics actually studied: 18-23;
• Ability to explore in a sufficiently independent way a certain number of subjects and discuss them: 23-28;
• Ability to critically discuss and explore the topics covered in the course, using scientifically correct language: 29-30. The professor awards honors based on the student's ability to professionally connect the various course topics and perform calculations on the dashboard.

Students cannot refuse a grade more than twice. The grade from the last exam attempt is valid.

Students with learning disabilities or temporary or permanent disabilities: please contact the relevant University office promptly (https://site.unibo.it/studenti-con-disabilita-e-dsa/it). The office will advise students of possible adjustments, that will be submitted to the professor for approval 15 days in advance. He/she will evaluate their suitability also in relation to the academic objectives of the course.

Teaching tools

PowerPoint presentations (made available on Virtuale) and dashboard for calculations.

Office hours

See the website of Cristian Vignali