Physics 443/543 and Astro 443 -- Spring 2017

Galaxies and the Milky Way

Professor: rachel somerville

hubble ultra deep fieldgalaxy imagecoma
Hubble Ultra Deep Field; Hubble Heritage image M66; Coma cluster

1. Overview and Course Description

Galaxies are an important nexus in the cosmic hierarchy: they serve as lighthouses marking out the vast cosmic structures that can span many millions of parsecs, but are fascinating in themselves as laboratories for the "small scale" processes of stellar birth and evolution. We now have images of billions of galaxies, and can observe them from a time less than a billion years after the Big Bang until the present day. We can study not only the appearance or "morphology" of galaxies, but also in some cases measure properties of their stellar populations, their quota of heavy elements, their gas content, and the internal motions (or kinematics) of their stars and gas. Although galaxies exhibit amazing diversity, they also conform to certain surprisingly tight correlations. From kinematic measurements, we can infer that galaxies contain a major unseen component that influences the motions of their stars and gas: the mysterious "dark matter". Moreover, the stars and gas that we can measure within galaxies falls far short of what we would expect for the cosmic "baryon budget". The study of modern galaxy formation focuses on trying to understand the observed demographics and correlations of galaxy properties and how these evolve over cosmic time, in the context of the "hierarchical structure formation" picture provided by the Cold Dark Matter theory.

In this course, we will warm up with a brief review of stars and radiative processes and basic cosmology. We will start our study of galaxies with our home Galaxy, the Milky Way, our sister galaxy M31 (Andromeda), and our smaller companions the Local Group dwarfs. Even this relatively small population of galaxies in our own "backyard" poses a number of unsolved puzzles. We will then cover the properties of spiral, lenticular, and elliptical galaxies in the 'nearby' Universe, and discuss the larger structures that form galaxy habitats: groups and clusters. One fascinating open question is whether galaxy properties are mainly shaped by "internal" processes or by their environment. We will discuss the evidence that many or even most galaxies harbor supermassive black holes in their nuclei. We will wind up the course with a discussion of how we can find and observe extremely distant (high redshift) galaxies, and of how galaxies were different in the past.

2. Instructor and Venue

Prof. rachel somerville
email: somerville [at]
office: 317 Serin
office hours by appointment

The course is scheduled for MTh in Serin 401

3. Class Format and Grading

The course will be run as a lecture/discussion, and in order for this to work well, it is imperative that students complete the assigned reading before class. Grades will be based on class attendance and participation, approximately 5 homework assignments, in-class quizzes, and a final paper and presentation. Sakai will be used to distribute and collect homework assignments.

4. Textbook

The main text for the course is Extragalactic Astronomy and Cosmology, Second Edition, by Peter Schneider. It should be available in the bookstore. Make sure you get the second edition!

Several other textbooks that may be useful for supplemental reading are: 

Galaxies in the Universe (Second Edition), by L.S. Sparke and J.S. Gallagher: classic undergraduate level textbook on galaxies
Galaxy Formation and Evolution by Mo, van den Bosch & White: a recent and comprehensive graduate level textbook.
Introduction to Cosmology by Ryden: very useful and clear text if you need to brush up on your cosmology
An Introduction to Modern Astrophysics by Caroll & Ostlie: useful basic reference

5. Students with Disabilities

If you have a disability, please contact Professor Somerville early in the semester to make the necessary arrangements to ensure a successful learning experience.

Click here for more information.

6. Useful links:

Rutgers Astronomy Group
Astrophysics Data System (ADS)
NASA/IPAC Extragalactic database (NED)
Millennium Simulation Database
Ned Wright's Cosmology Tutorial (and News)