Astronomy/Physics 228
Extragalactic Astronomy and Cosmology
(Spring 2025)

Assignments

Problem Set 9 (due 6pm Tuesday May 6)
Reading: Inflation
Presentation schedule

April 2 (Wed)
Katie Sharpe: H0 measurements. Talk slides.
April 7 (Mon)
Adam Fahs: LuSEE-Night experiment. Talk slides.
Olivia Aspegren: Axion dark matter. Talk slides.
April 9 (Wed)
Jyotsna Ravi: Probing dark matter with weak gravitational lensing. Talk slides.
Kendrick Nguyen: Properties of dark matter halos. Talk slides.
April 14 (Mon)
Saahit Mogan: Cosmic Microwave Background Anisotropies
Wendy Yang: Cosmological Simulations and Galaxy Mergers. Talk slides.
April 16 (Wed)
Savannah Cary: Fast Radio Bursts as a cosmology probe
Robert Loewe: Reionization and high-z universe
Guidelines for in-class presentations

The purpose of the in-class presentations is to give you a chance to investigate in some depth a current research topic in cosmology, using the knowledge you have gained in class. Unlike the standard physics courses (e.g. EM, quantum, stat mech), cosmology is an ongoing research field that is filled with new (and sometimes wrong) research results and opportunities. Hopefully you will get a taste of the excitement in this field. You will also get to practice giving talks, an integral part of a scientist's research life.

Each talk is 20 minutes long. The audience is your classmates, so pedagogy is important. Focus on questions such as: Why is it important (or is it)? How is it done? What have we learned? What to expect next? We will link your presentation slides for everyone's reference.

Some possible topics:
1. Mapping dark matter using strong gravitational lensing
2. Mapping dark matter using weak gravitational lensing
3. Cold dark matter searches: WIMPS
4. Cold dark matter searches: Axions
5. Hot dark matter: massive neutrinos and neutrino oscillations
6. Dark energy probed by supernovae
7. Dark energy probed by baryon acoustic oscillations
8. Distance ladder and the Hubble constant controversy
9. Cosmic Microwave Background: primary anisotropy by COBE, WMAP, Planck....
10. Cosmic Microwave Background: secondary anisotropy, the Sunyaev-Zeldovich effect
11. Cosmic Microwave Background: polarizations
12. Nonlinear structure formation: galaxy mergers
13. Nonlinear structure formation: properties of dark matter halos
14. Nonlinear structure formation: reionizations and high-z universe
15. You are encouraged to propose your own topic

Problem Set 8 (due 6pm Friday April 25)

Problem Set 7 (due 6pm Friday April 4)
Reading: Dark Matter

Problem Set 6 (due 6pm Tuesday March 18): An outline (at least 1 page) of your presentation. Sketch the scope of the talk.
Provide references (i.e. review/journal papers; web links ) that you are using to learn the topic. The more detail you provide, the more feedback we can give you.

Problem Set 5 (due 6pm Friday March 7)

Problem Set 4 (due 6pm Friday February 28)

Problem Set 3 (due 6pm Friday February 21)
Data from Table 4 of Riess et al. (2007)

Problem Set 2 (due 6pm Friday February 14)
Reading: Sec. 22.1 and 22.2 of Big Bang Cosmology

Problem Set 1 (due 6pm Friday February 7)
Reading: Sections 1.1-1.3 (pages 1-30) of Weinberg "The Expansion of the Universe"

Instructor: Prof. Chung-Pei Ma
Office: Campbell Hall 319
Email: cpma (at) berkeley.edu

Lectures: MW 10:10-11:30am in Campbell 501B

Office hours: MW 11:30-noon in Campbell 501B

Reader: Jacob Pilawa. Help session: W 5-6pm (zoom)
Email: jacobpilawa (at) berkeley.edu

Useful references:

Professional/graduate level texts
Particle Physics Group 2024 review articles
Steven Weinberg "Cosmology" (2008 Oxford University Press)
Scott Dodelson "Modern Cosmology" (2003 Academic Press)
John Peacock "Cosmological Physics" (1999 Cambridge University Press)
Undergraduate level texts
Barbara Ryden "Introduction to Cosmology"
Andrew Liddle "An Introduction to Modern Cosmology" (heavier emphasis on inflation)
Peter Schneider "Extragalactic Astronomy and Cosmology" (good coverage on astrophysical properties of galaxies, clusters and other important observational facts)
Popular level books
Steven Weinberg "The First Three Minutes" (a popular account of the thermal history of the universe)
Kip Thorne "Black Holes and Time Warps" (a beautifully written popular book on relativity)

Grading: 70% problem sets; 30% in-class presentation and participation/attendance

(Evolving and Expanding) Course Content:

1. The Smooth Universe: Friedmann-Robertson-Walker Model
1.1 The Cosmological Principle; Hubble parameter H; scale factor a
1.2 The Friedmann equation; equation of state; radiation, matter, dark energy
1.3 Density parameter Omega; open, flat, closed cosmological models
1.4 Time evolution of H, Omega, and a
1.5 Rudiments of general relativity; the Robertson-Walker metric
1.6 Basic kinematic properties: distance-redshift, time-redshift, age, angular sizes

Reference: PRD review article "Big-Bang Cosmology"; Weinberg Part 1 "The Expansion of the Universe"

2. The Bright Side: Thermal History of the Universe and Big Bang Nucleosynthesis
2.1 The Planck mass; the "ugliest" number in physics
2.2 Thermodynamics of Fermi and Bose gases in an expanding universe
2.3 The longest 3 minutes of your life
2.4 Light elemental abundances: helium, deuterium, lithium, baryon-to-photon ratio

Reference: PRD review article "Big Bang Nucleosynthesis"

3. The Dark Side
3.1 Evidence for dark matter
3.2 Evidence for dark energy
3.3 Two dark matter problems: baryonic vs non-baryonic
3.4 What can they be?

Reference: PRD review article "Dark Matter", "Dark Energy"

4. The Mildly Lumpy Universe: Linear Perturbation Growth
4.1 Gravitational instability in a static universe
4.2 Gravitational instability in an expanding universe
4.3 Time evolution of density and velocity fields; baryonic Jeans mass
4.4 Full linear perturbation theory: general relativistic and Boltzmann approach
4.5 Photon-baryon scattering physics; the cosmic microwave background

Reference: PRD review article "Cosmic Microwave Background"
Reference: Ma & Bertschinger (1995) "Cosmological Perturbation Theory in the Synchronous and Conformal Newtonian Gauges"

5. The Baby Universe
5.1 Successes of the standard Big Bang model
5.2 Problems of the standard Big Bang model
5.3 Phase transitions: classical scalar fields; equations of motion
5.4 Inflation: slow-roll; reheating; quantum fluctuations; the Harrison-Zeldovich spectrum

Reference: PRD review article "Inflation"

6. The Nonlinear Universe
6.1 The Press-Schechter model; excursion set theory
6.2 The halo model
6.3 Numerical simulations

7. Selected Topics (student presentations)

May 2025