Astronomy 640: Gravitational Accretion-Powered Astrophysics
 Spring 2011; MW 3:30 - 4:45; Room PA-216
"Observations and theory of accretion-powered objects and the high gravity environment: active galactic nuclei, accretion disks, interacting binary stars, compact objects; Introduction to nebular physics and high energy radiation processes."

Dr. William Welsh wfw@sciences.sdsu.edu
Office: P-235 Physics Building
Office Hours: MW 11:00-11:30, TTh 10:30-11:00, Fri 3:15-3:30; and/or by appointment
Class website: http://mintaka.sdsu.edu/faculty/wfw/CLASSES/ASTR640/astr640.html
Required Textbooks:
 * An Introduction to Active Galactic Nuclei Bradley M. Peterson (CUP)
* Accretion Power in Astrophysics (3rd Edition) Frank, King, & Raine (CUP)
See class website for other recommended books.
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Gravitational accretion processes are as fundamental as nuclear fusion in astrophysics. At the same time, accretion-powered systems are much more diverse, ranging from protostars to quasars. Accretion-powered systems can be vastly different in their masses, luminosities, sizes, and time scales, but the physical processes are generally similar. Students in this course will learn the key concepts of accretion-powered astrophysics, following an observational-based approach. Emphasis will be placed on accretion disks and Active Galactic Nuclei (and their associated Narrow Line Region nebular emission). In addition to the textbooks, students will read and digest relevant research papers from the astronomical literature. A term paper will enable students to explore a topic of their choice at a much deeper level than covered in the lectures.

Topics:
  • Introduction to Accretion Power and Accretion-Powered Systems
  • Introduction to Compact Objects: White Dwarfs, Neutron Stars, and Black Holes
  • Active Galactic Nuclei
  • Introduction to Nebular Physics
  • Accretion Disks I: Observations and Expectations
  • Accretion Disks II: Theory
  • Cataclysmic Variables and Soft X-ray Transients: Observations & Theory
  • Intro to High-Energy Emission Processes: Brems, (inverse) Compton, and Synchrotron Radiation

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    The course grade will be based on:
  • Class Participation/Discussion (5%)
  • Homework Assignments (15%)
  • Midterm Exam (30%)
  • Term Paper (15%)
  • Final Exam (35%)

    Important Dates:
  • Term paper topic: proposal for topics due before March 1
  • Term paper topic: must have approval by March 15
  • Midterm date: Wednesday March 23
  • Term Paper due date: Friday Apr 22 (at 1 pm)
  • Final Exam date: Friday, May 13, 3:30-5:30
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    Term Paper Information:
     The term paper should contain a review and clear presentation of the current understanding of the selected topic. Be sure to (i) Explain why the topic is important and (ii) summarize what we know and what we do not know.
  • Choice of topic is up to the student, but prior approval is required;
  • Submit a proposed paper topic (paragraph description with references) by no later than March 1;
  • The proposal will be accepted, rejected, or have revision required;
  • An approved paper topic must be ready by no later than March 15th;
  • Late paper proposals and approvals will reduce the grade by 1/3 letter per week;
  • Must be in ApJ Letter format, in LaTeX using the emulateapj style file;
  • Length of 3 journal-length pages (not including figures);
  • Must include equations, figures, abstract, and properly cited references;
  • Work should be at the graduate level.
    Look here for some examples of possible paper topics and for more information on the term paper.

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    Homework Philosophy:
     The homework assignments (15% of the course grade) are designed to be relatively easy and broad in scope. They are really a warm-up to get you thinking and exporing. Consequently:

    1) The goal is not to get the answer. The goal is for you to understand at a fundamental level what is going on. Think: What does the answer mean or imply? What are the consequences? You should always comment on the significance of your answer.

    2) As young scientists, you are mature enough to no longer be making "dumb mistakes". There will be no leniency for errors of this kind. Always check your work to make sure it makes sense.

    3) Do the homework on your own. You can check your answers with your classmates when you're done, but resist working in teams unless you are stuck; see me for help during office hours.

    4) A research astronomer doesn't have someone checking their results, so they have to be confident they have done things 100% correctly. Get out of the habit of answering questions as if they were homework questions and into the habit of solving things as if they were research problems. Do your homework such that you are confident of your answers/solutions. If you are unsure of anything, then seek help. In theory, I should not have to collect and grade the homework. Rather, we just discuss the topics that folks had difficulty with.
    * Students may be asked to present their homework solutions to the class on the blackboard.

    Late Homework and Term Paper Policy:
    Each homework is worth 50 points. Late homework will incur a penalty as follows: 3 points deducted for 1 day late, 1 point deducted each day thereafter. The maximum penalty is 10 points. For the term paper, 1/3 letter grade deducted per day late, up to a maximum of 1.3 letter-grade deduction. If a student is observing the night before an assignment is due, or if defending their thesis within +/-2 days of when the homework is due, an extension may be granted; prior approval is needed.