ASTR 640 Homework


Note: In general, the homeworks will be posted right after class on the day they are assigned. Prior to that, they are draft versions and may change. Draft versions are are available so you can get an idea of what is coming, but make sure to check for the real version of the homework.

Apr 27:
Reading Assignment: FKR's Accretion Power in Astrophysics Ch 4.1-4.7, and Ch 5.1-5.4.
Written Homework #9, due Wednesday May 4: Homework Problem Set 9 in PostScript

Apr 13:
Written Homework #8, due April 27:
Homework Problem Set 8 in PostScript.


Apr 4:
Reading Assignment:
- Peterson Ch 6
- Read the popular article ``Behind the Heavenly Glow'' by Gary Ferland in the 2006 July-August issue of ASP's Mercury magazine.
Written Homework #7:
Re-answer the questions on the exam that you had trouble with.

Mar 21:
(Study for exam on March 30)

Mar 14:
Reading Assignment:
- Carefully review Peterson Ch 5, especially 5.5 and 5.6
- Echo images of broad-line regions in active Galactic nuclei by Welsh & Horne 1991 ApJ 379, 586.
- The Masses of Black Holes in Active Galactic Nuclei by Bradley M. Peterson 2007 in ``The Central Engine of Active Galactic Nuclei'', ASP Conf. Ser. 373, Eds. Luis C. Ho and Jian-Min Wang (arXiv:astro-ph/0703197)
- Read FKR Chapter 8
Written Homework #6, due Monday March 21:
Homework Problem Set 6 in PostScript and [ in LaTeX ].

March 9:
Only Reading Assignments this week:
- Peterson Chapter 5
- Set of 4 AGN papers: Two conference proceedings by Begelman and by Madejski (handed out in class); Two review papers: (1) Active Galactic Nuclei and Quasars, 2010-2020 Science White Paper for the 2009 NRC Decadal Review by Elvis et al.; and (2) The Origins and the Early Evolution of Quasars and Supermassive Black Holes by Djorgovski et al.
- Read Two Echo Mapping papers:
(1) Keplerian Motion of Broad-Line Region Gas as Evidence for Supermassive Black Holes in Active Galactic Nuclei by Peterson, B.M. & Wandel, A. 1999 ApJ 521, 95
(2) Echo Mapping of Broad H beta Emission in NGC 5548 Horne, K., Welsh, W.F. & Peterson, B.M. 1991 ApJ 367, L5. Definitely read the textbook and the other echo mapping paper first.
- If you have not already done so, please examine John Kormendy's "Supermassive Black Holes in Galactic Nuclei" web page.

Feb 23:
Submit a 1-page typed Term Paper proposal. It should contain a title, brief description of the content of the paper, and a bibliography of at least 3 sources. (See the links to term paper grading critiera and additional information on the class website). The Term Paper proposal has been extended to Friday March 4th.

Reading Assignment:
- Peterson: Ch 4 (you can skip superluminal motion and blazars)
- Peterson: Ch 7
- Frank, King & Raine: 5.5 "The Emitted Spectrum"
- And please review Peterson: Ch 3
Written Homework, due March 2:
Homework Problem Set 5 in PostScript [ (in LaTeX).]

Feb 16:
- Reading Assignment:
(1) Frank, King & Raine: Ch 7.1 - 7.6
(3) Gravitational redshift and White Dwarf stars from the public information site "Einstein OnLine".
(4) Read at least the abstract of the paper: "A new Cepheid Distance the maser-host galaxy NGC 4258 and its implications for the Hubble Constant" by Macri et al. 2006 ApJ 652, 1133.
Written Homework, due Monday Feb 21:
Homework Problem Set 4 in PostScript [ Homework Problem Set 4 in LaTeX ]
The written homework requires the following paper:
"Possible power source of Seyfert galaxies and QSOs" Hills, J.G. 1975 Nature 254, 295.

Feb 2:
Reading assignment:
- Peterson: Ch 8
- Accretion Power: Ch 2.1-2.4.
- ``Infrared Adaptive Optics Reveals Stars Orbiting Within Light-Hours of the Milky Way's Center'' by Bertram Schwarzschild in the 2003 February issue of Physics Today. Though some values need updating, this well-written summary is still very good.
Written Homework, due Mon Feb 16:
Homework Problem Set 3 in PostScript [ Homework Problem Set 3 in LaTeX ]

Jan 26:
- Reading assignment:
Chapter 3 in Peterson's book.
Chapter 1 in Frank, King & Raine's (Accretion Power) book.
Written Homework, due Wed Feb 3:
 Homework Problem Set 2 in PostScript **CORRECTED **
Homework Problem Set 2 in LaTeX
Next week's written homework requires the following paper:
A Geometric Distance to the Galaxy NGC4258 from Orbital Motions in a Nuclear Gas Disk J.R. Herrnstein, J.M. Moran, L.J. Greenhill, P.J. Diamond, M. Inoue, N. Nakai, M. Miyoshi, C. Henkel, and A. Riess 1999 Nature 400, 539.

Jan 19:
Reading Homework:
- Read the popular article ``How Black Holes Helped Build the Universe'' by C. Wanjek in the 2007 Jan issue of Sky & Telescope magazine.
- Read Ch 1 and Ch 2 in Peterson's An Introduction to Active Galactic Nuclei.
- Read the article "Monsters at the Heart of Galaxy Formation" by John Kormendy 2000 Science, 289, 1484-1485. (NB: you can get a copy on Astro-ph or from Kormendy's website.)
- Review what is mean by "redshift".

Written Homework, due Wednesday Jan 26:
 Homework Problem Set 1 in PostScript
Homework Problem Set 1 in LaTeX

Note: Next week's written homework requires the following paper:
Miyoshi, M., Moran, J., Herrnstein, J., Greenhill, L., Nakai, N., Diamond, P. & Inoue, M. "Evidence for a black hole from high rotation velocities in a sub-parsec region of NGC 4258" 1995 Nature 373, 127




Homework Philosophy:
 The homework assignments (10% of the course grade) are designed to be relatively easy and broad in scope. They are really a warm-up to get you thinking. 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? Even if you are not asked to do so, you should comment on the significance of your answer.

  • 2) As young scientists, you are mature enough to no longer be making "dumb mistakes". There will not be much leniency for errors of this kind. Always check your work to make sure it makes sense.

  • 3) Try to 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 really stuck. Homework that is nearly identical to another student's will receive no credit.

  • 4) A research astronomer doesn't have someone checking their results, so they have to be confident they have done things 100% correctly. (Well, sometimes a referee of a paper will carefully checks things but they won't check everything.) Just a few errors will erode away the confidence of your colleagues to the point that they can't trust any of your research. Then your career grinds to a halt. 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 completely 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.

    Each homework is worth 50 points.
    Aim to get 45 points or above on each HW set.

    Late Homework Policy:
    Late homework will incur a penalty as follows:
    - 4 points deducted for 1 day late; 1 point deducted each day thereafter.
    The maximum penalty is 10 points (after 1 week). In other words, there is a floor beyond which no additional loss of points will occur. Even if you are 3 weeks late in doing the assignment, it is much better than not doing it at all. The only exception is if the answer to the homework question is discussed in class, in which case that problem is no longer valid for late credit; late homework earns zero credit for this problem.

    If a student is observing the night before a homework is due, the student can take 1 or 2 extra days to hand in the homework without penalty, ** with advanced permission.**
    If a student is defending their thesis (dissertation or paper) within +/- 2 days a homework is due, the student can get a few extra days to hand in the homework without penalty, ** with advanced permission.**