ASTR 222 - Galaxies and Cosmology

Spring 2023,
M/W 12:45-2:00
Department of Astronomy
Case Western Reserve University

Instructor: Professor Chris Mihos

Office: Sears 557
Office Hours: Mon/Wed 2-3, or drop-in (except the hour before class...).

Teaching Assistant: Ray Garner
Office: Sears 573
Office Hours: Tue 1-2, Fri 10-11, and whenever the door is open!

Course Websites:

Lecture Material, Syllabus, Schedule:
Homework and Grades: via Canvas

Textbooks: There are no required textbooks, but supplemental readings will be suggested from:

Foundations of Astrophysics, by Ryden and Peterson (RP)
Galaxies in the Universe, by Sparke and Gallagher (SG)

Other Help Sources:

Attendance Policy:

Regular, on time attendance is expected; habitual absences typically correlate quite strongly with poor academic outcomes. However, if you have an occasional need to miss a class, that's fine and there is no need to inform me ahead of time unless it is an extended situation (illness, travel, etc).

Grading Policies:

Homeworks can be discussed collaboratively, but each person must turn in their own solutions with unique writeup/analysis. Collaborative means talking with each other about approaches, techniques, etc. Collaborative does not mean sitting side-by-side working out the answers, or swapping final solutions to copy!

Homework should be submitted in the form of a pdf file, uploaded to the course Canvas page. Assignments are due at 5:00pm on the due date unless otherwise noted.

Late HW policy: You get one free late homework
(up to one week late), no questions asked. After that, it's a penalty of 20% for every day late, unless you have an prearranged, excused reason.

Missed test policy: Don't miss tests. If you are ill or have some other critical reason for missing a test, you must let me know in advance of the test, and document the reason through Undergrad Studies.

Grade Weights

Midterm #1
Midterm #2
Final Exam

Due Dates

(subject to change...)

HW #1
Feb 1
HW #2
Feb 22
Midterm #1
Feb 27
(in class)
HW #3
Mar 10, midnight
Midterm #1
rewrite (optional)
Mar 24
HW #4
Apr 5
Midterm #2
Apr 12
(in class)
HW #5
May 1
Final Exam
May 10
8:00 - 11:00
(in classroom)

Grading Scale


Schedule and Content

(all subject to change; red refers to previous years' notes)

Date Topics Lecture Notes
Other Materials

Astronomer's Toolbox
Statistics, Errors, and Fitting

Course Notes by Theme:
Milky Way (Jan 18 - Feb 13)
Galaxies (Feb 13 - Apr 5)
Cosmology (Apr 5 - Apr 26)

Jan 18 Intro to the Milky Way
Modeling Star Counts
Your ASTR221 notes!
RP: 19.1
Jan 23
Kapteyn and Shapley Models of the Milky Way
Metallicity and Chemical Evolution
Distances to Stars: Parallax
Distances to Stars: Main Sequence Fitting
SG 2.1.1, 2.2.3
Jan 25
Star Cluster Ages
The Complications of Dust
Pulsating Variable Stars
3D Dust Maps
RP 16.1, 17.3
Jan 30 Structure of the Milky Way: Disk, Bulge, Halo
The Interstellar Medium
Notes RP 19.1, 16.2
SG 1.2, 1.2.1
Feb 1
Solar Motion
The Velocities of Stars
The Oort Limit
Rotation Curve and Dark Matter
RP 19.2 - 19.6
SG 2.3
Jupyter Notebook: Boolean Flags
Feb 6
Statistics and Fitting
Description of HW #2
Jupyter Notebooks:
1) Counts/Histograms
2) Binning/Fitting

Feb 8

The Galactic Center
Satellite Galaxies
RP 19.7, SG 4.1
Satellite Galaxy animations:
1) Face-on
2) Edge-on
3) Fly-through
Feb 13
The Local Group
Intro to Galaxies: The Great Debate, Morphology, and General Properties
RP 20.1
SG 4.2, 1.3
Andromeda/MilkyWay merger animation
Feb 15
Stellar Populations, Surface Brightness, and Integrated Light
Stellar pop animations:
1) Single Burst models
2) Exponential SFR models
Feb 20
Coding Day

Feb 22
Spiral Galaxies I: Profiles, Colors, Gradients, and Kinematics
SG 5.1-5.4
Feb 27
Midterm Exam #1 (in class)
(covering material up to and including Feb 15)
Practice Midterm
Practice Midterm Answers
Equations and Constants

Bring a scientific calculator to the test!
Mar 1
Spiral Galaxies II: Spiral Structure and Bars
SG 5.5
M81 in blue and red filters
Solving Functions notebook
HW 3 Prob 1 guide
Mar 6
Discussion of HW #2
Elliptical Galaxies I: Structure, Colors, and Gas
SG 6.1, 6.3
Mar 8
Elliptical Galaxies II: Kinematics
Discussion of Midterm #1
SG 6.2, 6.4
Mar 13
Spring Break - no class

Mar 15
Spring Break - no class

Mar 20
Starburst Galaxies
Galaxy Interactions and Collisions
RP 22.2
SG 7.1.1, 7.1.2

Mar 22
Galaxy Interactions and Collisions (cont)
Extragalactic Distances and Hubble's Law

Mar 27
Active Galaxies and Quasars
RP: 21.1-21.3
SG: 9.1
Mar 29 Coding Day

Apr 3
Active Galaxies and Quasars (cont)
Galaxy Clusters
RP: 22.1-22.3
SG: 7.1-7.2
Galaxy Cluster Formation Movies:
Apr 5
Large Scale Structure
The Expanding Universe and Cosmological Parameters
RP: 22.3, 23.1-23.3

Apr 10
R(t): the Expansion History under Differing Cosmologies
Ages and LookBack Times
The Microwave Background
RP 23.1
Apr 12
Midterm Exam #2 (in class)
(covering material from Feb 22: Spiral Galaxies I through Apr 5: Large Scale Structure, and concepts in HW #3 and HW #4)
Practice Midterm
Equations and Constants

Bring a scientific calculator to the test!
Apr 17
Smoothness, Flatness, and Inflation
The "Cosmological Crisis" of the Early 1990s
CMB and Supernova Cosmology
The Modern Cosmological Model

Apr 19
Description of HW #5
Big Bang Nucleosynthesis

Apr 24
The Evolution of Early Density Fluctuations
Flavors of Dark Matter
Structure Formation
Hierarchical Galaxy Formation

Apr 26
Galaxy Formation Simulations
Observing High Redshift Galaxies
JWST and the Early Universe
Visuals shown in class:
May 1
The Future of the Universe
Ray's Notes
Andromeda / Milky Way merger movie
May 10
Final Exam (in class)
8:00am - 11:00am
Practice Final Exam
Equations and Constants

Bring a scientific calculator to the test!

Learning Outcomes

After taking this course, students should be able to:
  • Describe the structure and kinematics of the Milky Way galaxy.
  • Understand techniques for determining distances both within our Galaxy and to other galaxies.
  • Characterize the properties of galaxies of different morphological type.
  • Describe how galaxies cluster in the universe.
  • Understand the kinematic scaling relationships for galaxies of different types.
  • Explain how galaxy interactions drive evolution in galaxies and clusters.
  • Describe the various cosmological parameters and their effect on the expansion history of the Universe.
  • Derive quantitative relationships for the expansion history of the universe.
  • Describe qualitatively the evolution of the hot big bang model.
  • Describe the growth of structure and the evolution of galaxies as a function of cosmic time.
  • Describe current galaxy formation models.
  • Retrieve and use online datasets to study our Galaxy and other galaxies.
  • Write quantitative computational tools to analyse astronomical datasets.

Accessibility Statement

In accordance with federal law, if you have a documented disability, you may be eligible to request accommodations from Disability Resources.  In order to be considered for accommodations, you must first register with the Disability Resources office.  Please contact their office to register at 216.368.5230 or get more information on how to begin the process.  Please keep in mind that accommodations are not retroactive.

Academic Integrity Statement

Students at Case Western Reserve University are expected to uphold the highest ethical standards of academic conduct. Academic integrity addresses all forms of academic dishonesty, including cheating, plagiarism, misrepresentation, obstruction, and submitting without permission work to one course that was completed for another course.  Please review the complete academic integrity policy.  Any violation of the policy will be reported to the Dean of Undergraduate Studies and the Office of Student Conduct & Community Standards.