Open Questions: Galaxy Formation, Structure, and Evolution

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See also: Black holes -- Dark matter -- Quasars and active galactic nuclei -- Structure and evolution of the Milky Way -- The early universe -- Large-scale structure of the universe

An Eclectic Mix of Galaxies

From the HubbleSite Gallery


The intergalactic medium

Co-evolution of galaxies and massive black holes

The effect of dark matter on galactic structure

Galactic collisions

Recommended references: Web sites

Recommended references: Magazine/journal articles

Recommended references: Books


Recommended references: Web sites

Site indexes

Open Directory Project: Galaxies
Categorized and annotated links. A version of this list is at Google, with entries sorted in "page rank" order. May also be found at Netscape.
Galaxy: Galaxies
Categorized site directory. Entries usually include descriptive annotations. Additional listings here.

Sites with general resources

Hubble Deep Field
Part of the Space Telescope Science Institute site. Contains information on the Hubble Deep Field project and a variety of images. Since the galaxies involved are all viewed at a much earlier age, many are quite unlike galaxies in the present stage of evolution.
Cardiff University Galaxies Group
Research group which is part of the School of Physics and Astronomy at Cardiff University (Wales). Pages describe research interests and include links to related information. There is a related group investigating the Chemical Evolution of Galaxies. Another group for Observational Cosmology deals with histories of galaxies and large-scale structure.
Introductory and background information, with links to other sites and pictures.
Strange Galaxies
A list of unusual galaxies, by Sten Odenwald.
GAIA: Composition, Formation and Evolution of the Galaxy
Detailed report on galaxy formation and evolution, which is to be studied by the GAIA Mission of the Astrophysics Division of the European Space Agency.
Galaxy Evolution Explorer
NASA satellite observatory that studies star formation and galaxy evolution in ultraviolet light. Site includes a good image gallery.
Galaxy Evolution Explorer
NASA page that contains a relatively brief description of the experiment.
The Merger of the Milky Way and Andromeda Galaxies
Striking images from a numerical simulation of the collision between the two galaxies, by John Dubinski.

Surveys, overviews, tutorials

Galaxy formation and evolution
Article from Wikipedia. See also Galaxy.
Galaxies - The Spiral Nebulae
Good explanations and external links, part of Gene Smith's Astronomy Tutorial.
Part of the Cambridge Cosmology site. Contains material on the Milky Way, galaxies in general, galaxy clusters, dark matter, and the origin of large-scale structure.
Frequently Asked Questions in Astronomy: Galaxies, Clusters, and Quasars
Questions and answers from the Usenet sci.astro newsgroup.
How does your galaxy grow?
July 2009 New Scientist article. "The idea that galaxies can create stars only in violent mergers is itself taking a bashing."
A ScienceWeek "symposium" consisting of excerpts and summaries of articles from various sources.
Discovery of a 'Dark' Galaxy
Brief page about the claimed discovery of the first "dark galaxy". There's a technical paper with much more information.
Simulating the Fate of Our Milky Way
May 2002 article from Discusses simulations of the process of galactic collisions and how they help explain the development of structure in galaxies.
The Origin of Galaxies
January 2002 article from Discusses the problems of explaining the details of exactly how galaxies formed.
Clues to Early Universe in Three New Hubble Images
January 2001 article from Presente recent Hubble telescope images of nearby galaxies that help illustrate different aspects of galactic structure.
Galaxies: Islands in the Void
Good reference article from
Other Galaxies and Active Galaxies
Part of a course in astronomy by Nick Strobel.
StarDate Online: Galaxy Guide
General overview information on galaxy formation and evolution, at the StarDate Online site.
Distant elements of surprise
July 2003 article from Physics World, by Max Pettini. "The fortuitous alignment of a quasar and a distant galaxy has enabled astronomers to unravel the origin and evolution of chemical elements."
How are galaxies made?
May 1999 article from Physics World, by Carlton Baugh. "Galaxies have been forming since the universe was less than 10% of its current age - as supercomputer simulations predict and observations have confirmed."
The most distant object in the universe
April 1999 news article from Physics World, about the observation of a galaxy at a red shift of 6.68.
Dark Matter and Galaxy Formation
Research paper by K. C. Freeman.
Galaxy Cannibalism
A lecture on galactic dynamical evolution (collisons, accretion, mergers), by James Schombert.
Galaxy Evolution
A lecture by James Schombert.
Mystery compact objects in the Fornax cluster
A page by Michael Drinkwater about the discovery of compact objects in the Fornax cluster that have been determined to be the smallest known galaxies, called "ultra compact dwarf galaxies".

Press releases, news stories

A Puzzle of Galactic Evolution is Solved - Massive Gas Clouds Seed the Galaxy with the Stuff of Stars
November 24, 1999 press release and related information from the Space Telescope Science Institute.
Multiple Galaxy Collisions Surprise Hubble Astronomers
November 22, 1999 press release and related information from the Space Telescope Science Institute.
Hubble's Ultraviolet Views of Nearby Galaxies Yield Clues to Early Universe
January 11, 2001 press release and related information from the Space Telescope Science Institute.
Stars Forged in Galactic Battle
March 2001 Scientific American news story about the starburst galaxy M82.
The Hole Shebang
October 2000 news article from Scientific American. Subtitled "Black holes and galaxies may be entwined from birth".
Gas cloud points to earlier galaxies
January 2001 news article about discovery of a very large gas cloud at a distance of 12 billion light years, implying large galaxies could have formed very early in the universe without growing by mergers of smaller galaxies.

Recommended references: Magazine/journal articles

Viewing galaxies in 3D
Davor Krajnović
Physics World, November 2011, pp. 26-30
Thanks to a technique that reveals galaxies in 3D, astronomers can now show that many galaxies have been wrongly classified. It's argued that the classification scheme proposed 85 years ago by Edwin Hubble now needs to be revised.
New models of galaxy formation show the gastro in physics
Ron Cowen
Science News, March 22, 2008
Crisis in the cosmos?
Ron Cowen
Science News, October 8, 2005
The Midlife Crisis of the Cosmos
Amy J. Barger
Scientific American, January 2005
A Universe of Disks
Omer Blaes
Scientific American, October 2004
The Unexpected Youth of Globular Clusters
Stephen E. Zepf; Keith M. Ashman
Scientific American, October 2003
Mature Before Their Time
Ron Cowen
Science News, March 1, 2003
Milky Way's Last Major Merger
Ron Cowen
Science News, December 14, 2002, pp. 376-377
Recent evidence indicates that the Milky Way collided with a smaller galaxy about 10 billion years ago. This was the last significant event of its kind for our galaxy, and much the same scenario may well be applicable to most other galaxies also.
The Life Cycle of Galaxies
Guinevere Kauffmann; Frank van den Bosch
Scientific American, June 2002
Here, There, and Everywhere?
Steve Nadis
Astronomy, February 2001, pp. 34-39
It appears that supermassive black holes are found at the center of almost every large galaxy in the universe. So there is very likely a connection between the formation of galaxies and the central black holes. Yet is isn't even clear now which came first.
Dwarf Galaxies & Starbursts
Sara C. Beck
Scientific American, June 2000, pp. 66-71
Dwarf galaxies have been little studied since they are so faint. But recent research has shown they may experience dramatic bursts of star formation. This phenomenon may offer insights to the early history of the universe.
Clusters in Collision
David Graham
Astronomy, May 1999, pp. 58-63
A great deal about galactic evolution can be inferred from a study of collisions between clusters of galaxies.
Galactic Genesis
David J. Eicher
Astronomy, May 1999, pp. 38-47
Good survey article on many aspects of galaxy formation and evolution, including mergers, structure, star formation.
Before Galaxies Were Galaxies
William Keel
Astronomy, July 1997, pp. 58-63
The most recent observations are finally making it possible to understand how galaxies formed out of a very uniform distribution of matter in the early universe.
Galaxies in the Young Universe
F. Duccio Macchetto, Mark Dickinson
Scientific American, May 1997, pp. 92-99
Hubble Deep Field observations of galaxies in the early universe allow comparison of the properties of current galaxies with those in an earlier stage of evolution.
Probing the Faintest Galaxies
Henry C. Ferguson, Robert E. Williams, Lennox L. Cowie
Physics Today, April 1997, pp. 24-30
A mass of data from the Hubble Space Telescope and new ground-based telescopesis helping to clarify the process of galaxy formation in the early universe.
Giving Birth to Galaxies
Marcia Bartusiak
Discover, February 1997, pp. 58-65
Observation of the most distant galaxies, which are seen in the distant past in the early universe, is helping the understanding of galaxy formation.
The Ghostliest Galaxies
Gregory D. Bothun
Scientific American, February 1997, pp. 56-61
Observation of many "low surface brightness" galaxies is altering theories of galaxy evolution and mass distribution in the universe.
What Makes Galaxies Change?
Marcia Bartusiak
Astronomy, January 1997, pp. 36-43
The Hubble telescope has made it possible to image galaxies as they existed in the early universe. This has helped understand how a galaxy's life cycle is influenced by both "nature" and "nurture".
Galaxies Colliding in the Night
Damond Benningfield
Astronomy, November 1996, pp. 36-43
Collisions between galaxies are not uncommon and often lead to mergers, but always significantly affect the evolutionary history of the galaxies involved.
Experimenting with Galaxies
Richard H. Miller
American Scientist, March-April 1992, pp. 152-163
Before the availability of sufficiently powerful computers, the study of galactic behavior was not an experimental science. But now computer models illuminate a variety of galactic dynamical behavior, including vibration, instabilities, and collisions.
The Formation of Galaxies
Joseph Silk
Physics Today, April 1987, pp. 28-35
Questions about how galaxies and clusters of galaxies form and evolve are interesting in themselves. But answering them is entwined with our understanding of cosmological questions such as the nature of dark matter and the earliest history of the universe itself.

Recommended references: Books

Malcolm S. Longair -- Galaxy Formation
Springer-Verlag, 1998
There isn't much to say about the subject of galaxy formation without going into a serious mathematical treatment, and Longair's book is a textbook written for upper-level college students which provides exactly that. And not only that, but it is a fine textbook for much of cosmology as well, since it contains chapters on large-scale structure of the universe, galaxy clustering, relativistic cosmological models, the big bang, nucleosynthesis, the cosmic microwave background, and dark matter. You wouldn't need a separate text on cosmology; this one does it all.


Copyright © 2002 by Charles Daney, All Rights Reserved