Physics 610: Interstellar Matter
Fall 2025

Instructor Andrew Baker Serin W309 Phone: 848-445-8887 Email: ajbaker[at]physics.rutgers.edu Office hours: Wednesday 12-1pm & 5-6pm Venue TTh5 (3:50-5:10) in SERC 216

Textbook
The only required textbook is Physics of the Interstellar and Intergalactic Medium by Bruce Draine, copies of which should be available in the bookstore.

Overview
Here's the official course catalog listing:
"Structure of the interstellar medium: its molecular, neutral atomic, and plasma phases. Radiative transfer, dust, particle acceleration, magnetic Fields, and cosmic rays. Effects of supernovae, shock fronts, and star formation."

I plan to broaden this list of topics to include the intergalactic medium; in general, I will try to highlight subjects that are important to areas of current research in extragalactic astrophysics and cosmology (e.g., galaxy formation, the enrichment of the intergalactic medium, and the reionization of the universe).

Schedule
Both the sequence of lectures and the assignment due dates are preliminary at this point; I will update them as needed during the course of the semester. The last two lectures are tentatively reserved for ISM-related topics to be chosen sometime after Thanksgiving by the students who are officially enrolled in the course. These will give you an opportunity to make me sweat, thus exacting revenge for a semester's worth of problem sets.

I will include in the schedule the dates of any local talks that are relevant to the subject matter of this course. Attendance is encouraged but not required!

LECTURE	DATE	TOPIC	TEXT	DUE
1	Sep 2	chemical composition of the ISM	D 1.1-1.2
2	Sep 4	radiative transfer; thermal emission	D 7 (RL 1)
3	Sep 9	free-free; synchrotron
4	Sep 11	emission and absorption lines		PS1
5	Sep 16	guest lecturer: Blakesley Burkhart tracing hydrogen in the ISM
6	Sep 18	HII regions		PS2
7	Sep 23	guest lecturer: Eric Gawiser atomic structure; recombination lines
8	Sep 25	guest lecturer: Shyam Menon (TBC) collisional excitation		PS3
9	Sep 30	nebular emission-line diagnostics
10	Oct 2	thermal equilibrium in ionized gas		PS4
11	Oct 7	thermal equilibrium in neutral gas; ISM phases
12	Oct 9	interstellar dust: observations		PS5
13	Oct 14	interstellar dust: properties
14	Oct 16	interstellar dust: physical processes		PS6
15	Oct 21	molecular spectroscopy
16	Oct 23	molecular clouds		PS7
17	Oct 28	PDRs and molecular chemistry
18	Oct 30	interstellar magnetic fields		PS8
19	Nov 4	fluid mechanics: basics
20	Nov 6	formation of individual stars		PS9
21	Nov 11	interstellar shocks
22	Nov 13	stellar winds and supernova blast waves		PS10
23	Nov 18	the three-phase model of the ISM
24	Nov 20	star formation on galaxy scales		observing proposal
25	Nov 25	feedback on galaxy scales
26	Dec 2	fluids as continua
27	Dec 4	fluid instabilities		PS11
28	Dec 9	magnetohydrodynamic waves

Grading
Your course grade will be based on a weighted combination of three elements:

• problem sets (40%)
• observing proposal (30%)
• final exam (30%)

The observing proposal will be for a telescope of your choice and on a topic of your choice, although it should not be identical to a research project or a qualifier paper you are already working on. Students who are pursuing research in astronomy may find their proposals can be revised and submitted for real at the relevant proposal deadlines. For any student who is not pursuing research in astronomy, I will provide a set of literature papers that can serve as a starting point for building up the requisite background knowledge.

The final exam will be closed-book and closed-note. At least some questions on the exam will be drawn from a list that I will provide you with in advance.

Other items

• Absences
  I will have to miss at least three of our regularly scheduled classes. These will either be delivered by guest lecturers in my absence or rescheduled at an alternative time. If you need to miss a class for some reason, there will be no penalty to your grade; however, since I will not be posting my notes to the course website, you will generally need to rely on your classmates' notes to catch up. (I will aim to provide the equations from my notes for each lecture, but without the context of the lecture these are likely to be less useful.)
• Late assignments
  I am willing to be somewhat flexible, but for problem sets that are turned in later than 11:59pm on their nominal due dates, I will generally start docking points at a rate of 10% off the top per day.
• Collaboration policy
  On the problem sets, you should first try every exercise yourself without discussing it with others. If you get stuck (or finish and would like to compare answers), you may discuss exercises with other students in the course and/or me, but you should always write up your own solutions. You may consult books and published papers, but not old solution sets from previous offerings of this course or similar courses elsewhere.
• AI policy
  You may not use AI tools (other than spelling/grammar checkers) to help you complete any assignment in this course.
• Auditors
  Students not enrolled for credit are welcome to attend the lectures by permission of the instructor.
• Students with disabilities
  If you have a disability, let me know early in the semester so that we can make the necessary arrangements for you to have a successful learning experience. Please consult this web page for more details.