Dunkle Materie (Vorlesung & Seminar)

When: Wednesdays 16:15 – 17:45, Summer Semester 2022

Where: Room 2.28. 2.011, University of Potsdam

Who: Dr. Marcel S. Pawlowski

Slides and literature (password protected): AIP Cloud

Description

The course will provide an introduction to the topic of Dark Matter, its background, and current debates around its nature. It will start with a historical overview of how the concept of dark matter was developed. This will be followed by summaries of different lines of observational evidence pointing to its existence, ranging from the dynamics of galaxies, over clusters of galaxies, to cosmological scales. We will then discuss what dark matter might be, ranging from early baryonic dark matter candidates and why they were ruled out, to non-baryonic particle dark matter candidates. In addition, the successes and problems of an alternative approach of modifying the laws of gravity in the low-acceleration regime will be presented. After a discussion of ongoing direct and indirect detection experiments for dark matter, we will spend the rest of the course on the current ‘standard’ model of cosmology Lambda Cold Dark Matter (LCDM), ranging from its implementation on cosmological simulations, possible other detection avenues revealed by simulation predictions, and finally problems on small scales, and possible solution to these.

Set-up of the course

Since the topic of Dark Matter  is one of active scientific research, and its nature is an as-yet unsolved question, the focus of the course will not only be on merely disseminating. Instead, its aim is to provide an understanding of the process of scientific research, provide a glimpse at ongoing scientific debates, and an introduction of the current status of research. 

The course will consist to equal parts of a lecture component introducing concepts, methods, and results, as well as a more interactive component in which the students are asked to contribute. 

For the latter, we will have open discussions on the topics introduced in the lecture. In addition, each student will have to present and (co-)lead one such session. This could either be a typical seminar talk of ~½ hour presenting a classic paper in the field (see below for an incomplete list), or the preparation of a discussion session with the class consisting of a brief (~10 min) introduction followed by leading a debate on a question related to dark matter. For the latter, two students can team up (but will need to present opposing views during the discussion). The seminar talks will be scheduled in the first ~half of the semester, the discussions in the second half.

Requirements for passing

To successfully pass the course, the students will be required to 

• attend most of the lectures,
• actively contribute to discussions by asking questions or offering answers, and 
• present a talk or lead a discussion in one session.

There will be no grades, and no exercise classes in this course.

Learning Outcomes

At the end of this course, you should be able to

• explain the different lines of evidence for a missing mass problem / for dark matter
• summarize different dark matter candidates
• explain why which candidates are viable and others not
• discuss the main pros and cons of the alternative modified gravity approach MOND
• Talk about different avenues by which the existence of dark matter could be verified experimentally or observationally
• Introduce the LCDM model, the basics of cosmological simulations, and current open issues such as some small-scale problems.

Covid considerations

The pandemic is not over, and even though we will try to have an in-presence course, I ask you to follow the following precautions:

• wear a mask while in class
• do not come to the lecture should you have any symptoms.
• test regularly

I will try to live-stream the course via Zoom for a hybrid on-presence/online format if one of the participants can’t attend a given lecture. Please inform me as soon as you know that you will not be able to attend in person on a given day.

The same rules of course apply to me. Should I have any symptoms, I will switch a session to an online-only format or cancel class.

Some Possible Topics for Talks or Discussion Sessions

Talk topics:

• Analogies: Discovery of Neptune vs. non-discovery of Vulcan
• Classical papers, e.g.:
  • Zwicky, F., “Die Rotverschiebung von extragalaktischen Nebeln”, Helvetica Physica Acta, vol. 6, pp. 110–127, 1933. (English translation) 
  • Freeman, K. C., “On the Disks of Spiral and S0 Galaxies”, The Astrophysical Journal, vol. 160, p. 811, 1970. doi:10.1086/150474.
  • Rubin, V. C. and Ford, W. K., “Rotation of the Andromeda Nebula from a Spectroscopic Survey of Emission Regions”, The Astrophysical Journal, vol. 159, p. 379, 1970. doi:10.1086/150317.
  • Ostriker, J. P., Peebles, P. J. E., and Yahil, A., “The Size and Mass of Galaxies, and the Mass of the Universe”, The Astrophysical Journal, vol. 193, p. L1, 1974. doi:10.1086/181617.
  • Einasto, J., Kaasik, A., and Saar, E., “Dynamic evidence on massive coronas of galaxies”, Nature, vol. 250, no. 5464, pp. 309–310, 1974. doi:10.1038/250309a0.
• "Small-scale problems" of cosmology (pick one):
  • Missing Satellites
  • Core-Cusp
  • Too-Big-To-Fail
  • Planes of Satellite Galaxies.
• A galaxy without dark matter, as proof of dark matter’s existence? (would also work as a discussion topic)

Discussion topics:

• Dark Matter and Philosophy of Science: Karl Popper vs. Thomas Kuhn
• Verifying Dark Matter: (How) can we (best) find evidence for dark substructures?
• Dark Matter vs. Modified Gravity
• Small-scale problems of LCDM: What solution is best?

List of sessions

• 20.4.2022: Introduction
• 27.4.2022: A historical perspective: How Dark Matter came to matter + planning of student-led discussions / seminars
• 4.5.2022: Missing Mass in Galaxies: Rotation Curves
• 11.5.2022: Missing Mass in Galaxies: Dwarf Galaxies
  TALK (Tevlin: ETHOS)
• 18.5.2022: Missing Mass in Galaxy Clusters
  TALKS (Mudimadugula: Zwicky)
• 25.5.2022: cancelled
• 1.6.2022: Cosmological Scales, CMB, BBN
  TALKS (Rueda Vargas: Ostriker &  Itzerott: Galaxy without DM)
• 8.6.2022: DM Candidates: Baryonic Dark Matter
  TALK (Cediel Ramos: Freeman)
• 15.6.2022: Particle DM and Detection Experiments
  TALK (Rajkumar: Einasto)
• 22.6.2022: substitute lecturer: Dr. Salvatore Taibi – Dark Matter in Dwarf Galaxies
• 29.06.2022: cancelled
• 6.7.2022: Modified Gravity
  DISCUSSION (Boye & Faber: DM/MOND)
• 13.7.2022: Modified Gravity
  DISCUSSION (Samieadel & Weber: Popper/Kuhn)
• 20.7.2022: LCDM, structure formation, simulations, small-scale problems
  DISCUSSION postponed to following week
• 27.7.2022: Possible Solutions to Small-Scale Problems: Baryons in Simulations, Warm & Self-Interacting Dark Matter
  DISCUSSION (Muralichandran & Özdemir: Dark Matter Substructures and Small-Scale Problems)