2012 Winter Term, Caltech

Meets in 219 Cahill. Tuesday 2:30-3:30pm, Wednesday 2:30-3:30pm, Friday 3:00-4:00pm Homework help session: Sundays, 5:00pm starting Jan 15, in 219 Cahill., or by appointment with the TA or instructor. If you have an ID card with an RFID chip, you will just need to get your UID entered in the Cahill access list: see Gina Armas in 246 Cahill. If your ID card does not have an RFID chip, you will need to get a new one.

Prof:   Sterl Phinney
        316 Cahill
        x 4308
        esp [at] tapir . caltech . edu
	Office hours: by appointment

TAs:	Sebastian Pineda
        Cahill 264, extension 3030
	jspineda [at] astro . caltech . edu
	Office hours: 4-6pm Sunday or by appointment



TEXTBOOKS (Required):

An Introduction to Modern Astrophysics (2nd Edition, 2007)
by Bradley Carroll and Dale Ostlie
ISBN 978-0805304022
(Pearson/Addison Wesley/Benjamin Cummings)
Textbook's website (errata, computer programs, data, links) is here. This is the same book used in Ay 20 for the last several years, so most Ay 21 students should already own it (which is why I am recommending it for Ay 21). If you do not already have it, you can buy the version that is only the extragalactic part, or you can borrow a copy.

TEXTBOOKS (Recommended):

Astrophysics in a Nutshell
by Dan Maoz
ISBN 978-0-691-12584-8
(Princeton University Press)
This was also recommended for Ay 20 last term. The cosmology is basic and very concise, and we will go into more depth, but it provides a nice introduction.

Other useful references:

An Introduction to Modern Cosmology (2nd Edition, 2003)
by Andrew Liddle
Covers the smooth universe (no galaxies or stars!) at undergrad level in only 156 pages!
Physical Cosmology (1971)
by P.J.E. Peebles
(Princeton U. Press)
Out of date in all the observations, but still unsurpassed for the clarity of the exposition of the physics. [the library has 5 copies]


  1. Historical Introduction
  2. Galaxies: properties, distributions
  3. Distance Scale, Cosmography I
  4. Equations governing the expanding universe, Cosmography II
  5. Physics of the (Moderately) Early Universe,
  6. The hot big bang: nucleosythesis, Cosmic Microwave Background
  7. Formation of structure. Links to movies of simulations Millenium DM, Dubinski DM, Via Lactea DM, Milky Way gas/stars (link at bottom), a real paper on the latest large DM simulation Bolshoi and some pretty pictures from it and the whole repository. Galaxy merger with stars and gas. Reviews of cosmology: N-body and cosmological simulations.
  8. Clusters of Galaxies, The cosmic web and IGM
  9. Active Galactic Nuclei
  10. Supermassive Black holes and galaxy co-evolution
  11. Ultra-high energy cosmic rays, neutrinos and gravitational waves
  12. Gravitational lensing, weak and strong
  13. First light: the reionization Era
  14. Physics(?) of the Very Early Universe: Inflation, gravitational waves, baryogenesis



There will be approximately weekly homework sets (with an option to replace any two by a 4-page term paper: see below), an open textbook midterm, and a closed-book final exam.

You may optionally write a 4-page paper on any subject in cosmology, which can replace (in grade) any two homework sets of your choosing. However, if you think you wish to exercise this option, you must hand in, at the latest with your midterm, an outline of this paper, listing the subject, the scope, and at least 3 primary references (with page numbers) which you intend to use for the research in the paper. The instructor will determine if the proposed topic and references are suitable, and provide guidance if they are not. Your grade will be a monotonic function of the following combination of homework(+paper if chosen), midterm and final scores
g = [0.55(sum of homework scores)/(total possible) +0.2(score on midterm)/(total possible) +0.25(score on final)/(total possible)].


There will be approximately weekly homework sets due in each Tuesday's class, one week after they are posted on this website (see homework link at left). Late homework will not be accepted except by prior arrangement (see below). The problem sets are intended to be fun. Therefore, if you spend more than 1/2 hour on any problem, and still feel lost, come see one of us for preparation suggestions or a hint. Graded homework will be returned in class. Dead homework may be collected from a box outside TBD Cahill.


Homework extensions of up to 24 hours can be granted by the TA. Longer extensions can only be approved by Sterl. No late homework will be accepted unless one of these prior arrangements has been made. Unapproved late homework will not be graded.


In working the homework sets, you may consult your own class notes (which must be written in your own hand from lecture or those of another student; they may not be xerox or scanned copies), and any textbooks required or recommended for this class or any other reference books you find helpful (but please state which you use, if you do use books which are not the texts). You may also use calculator or a computer to do numeric and symbolic calculations, or as a word processor. During the midterm, you may use only your own class notes, your own and official homework solutions, the course's one required and one recommended text, and a calculator. During the closed-book final, you may not consult any texts, computers or people. You may use a calculator.

Collaboration on the homework is limited. At no stage may you look at solutions to the problems you might find on friend's desks, on websites, filing cabinets, ftp sites, etc. You must first try every homework problem BY YOURSELF. without external help. This is the educational part.

Visual exchanges of information are strictly forbidden -you may not trade equations, graphs, or look at other people's solution sets from this or any prior year or similar courses at other universities.

You may consult books and published papers to learn or remind yourself of relevant physics or astronomy. The texts are recommended as a first source. Please do read the suggested readings before starting the homework.

If you get stuck, you can TALK about the homework with the TA or your fellow students, but all exchanges of information must be general in nature and either exchanged verbally, or with modern replacements for talking (i.e. texting, IMing and emailing is ok too, as long as details are avoided -see below). For example the following QandA is ok Q: "I got a mean density of the universe today of 1000 grams per cubic centimeter. That seems high. A: "Yup, sure is. Whoa -did you say here a galaxy is 10,000 cm in diameter? Isn't it more like 10,000 parsecs? The following one is NOT OK: Q: "I'm stuck on problem 2. Can you help me?" A: "Sure. You take equation 3.12 of this book, insert equations 2.5 and 3.2, integrate and you should get the right answer which is V k squared over pi squared".

After any discussion with others, you must write up your own homework by yourself, without reference to anyone else's.

In real research, no one else knows the answer to the problems you work on (otherwise why would you be doing them?), so the most important thing you can learn from homework is how to think and solve for yourself, and be confident in your answers.