Faculty Description

Research Statement
  • My field of interest is galaxy formation. I am investigating the early phases of evolution, when protogalaxies separated from the expanding background and collapsed under gravity. I am specifically interested in the set of events that gave rise to the rotating disks of stars and gas that we find in spiral galaxies today. Theories of galaxy formation predict somewhat different conditions as massive clouds of gas collapse to form galaxies in the early Universe. We look back in time some 10 to 15 billion years at remote clumps of hydrogen gas and stars with rather large cosmological redshifts.
    Since the starlight emitted by such distant objects is exceedingly faint, I have focused on the interstellar gas. To study its composition, temperature and motion, we use the light of distant quasars located behind the protogalactic clouds. As the quasar light passes through the gas, some of it is absorbed by hydrogen molecules and other elements,leaving an "absorption -line" signature. Of particular interest is the "damped Lyman-alpha" absorption, produced by cold, neutral hydrogen gas. Surveys with large optical telescopes have been used to search for these damped Lyman-alpha absorption systems. The results of the surveys show that most of the known matter in the distant, early universe is contained in these cold, quiescent layers of neutral hydrogen that are responsible for the damped Lyman-alpha lines. Moreover, the co-moving density seen in these clouds is similar to the density of visible matter in current spiral galaxies. Therefore, the implication is that we have detected the component in the early universe that makes up the present stellar content of galaxies.
    We are currently using the Keck Telescope with its high-resolution spectrograph to study damped Lyman-alpha and other absorption features that we associate with protogalactic disks. The kinematics of the clouds provide information about the newly-formed disks, their rotational and random motions. We can also learn about the abundances of elements heavier than hydrogen, which tells us about the star-formation history in these systems.
Awards & News
  • Art Wolfe, UCSD Distinguished Astronomer, Awarded Jansky Lectureship
  • Associated Universities, Inc. (AUI), and the National Radio Astronomy Observatory (NRAO) have awarded the 2008 Karl G. Jansky Lectureship to Dr. Arthur M. Wolfe of the University of California, San Diego (UCSD). The Jansky Lectureship is an honor established by the trustees of AUI to recognize outstanding contributions to the advancement of radio astronomy.
    Dr. Wolfe has made major contributions in several areas of astronomy. Along with Rainer Sachs, he predicted the Sachs-Wolfe Effect, a phenomenon which forms the basis for modern precision cosmology using the background radio emission left over from the Big Bang. In the 1970s, he discovered that light emitted by very distant galaxies is absorbed by hydrogen atoms in previously-undetected intervening gas clouds. From the 1980s until the present, he used optical light emitted by distant quasars to show that these clouds are the progenitors of stars found in modern galaxies. This phenomenon has since been used extensively to study the production of heavy elements and history of star formation in the Universe. He also did landmark research on whether the fundamental constants of nature, such as the charge of the electron and the masses of elementary particles, do, in fact, remain constant through cosmological time.
    Dr. Wolfe was the Director of the Center for Astrophysics and Space Sciences at UCSD from 1997 to 2007. He joined UCSD as a Professor of Physics and Astronomy in 1989, leaving the University of Pittsburgh, where he had taught since 1973. He holds the Chancellor's Associates Chair of Physics at UCSD. Dr. Wolfe received his Ph.D from the University of Texas at Austin. He is a Fellow of the American Academy of Arts and Sciences, and received the Sackler Fellowship of the Institute of Astronomy at the University of Cambridge, UK, in 2004.
    As Jansky Lecturer, Wolfe will give a presentation entitled, Finding the Gas that Makes Galaxies, at NRAO facilities in Charlottesville, Virginia, Green Bank, West Virginia, and Socorro, New Mexico. The dates of these scientific lectures, which are open to the public, will be announced later.
    This is the forty-third Jansky Lectureship. First awarded in 1966, it is named in honor of the man who, in 1932, first detected radio waves from a cosmic source. Karl Jansky's discovery of radio waves from the central region of the Milky Way started the science of radio astronomy. Other recipients of the Jansky award include five Nobel laureates (Drs. Subrahmanyan Chandrasekhar, Arno Penzias, Robert Wilson, William Fowler, and Joseph Taylor) as well as Jocelyn Bell-Burnell, discoverer of the first pulsar, and Vera Rubin, discoverer of dark matter in galaxies.
    The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

    Complete Story
  • First Detection of Magnetic Field in Distant Galaxy Produces a Surprise
  • Using a powerful radio telescope to peer into the early universe, a team of California astronomers has obtained the first direct measurement of a nascent galaxy's magnetic field as it appeared 6.5 billion years ago.
    Astronomers believe the magnetic fields within our own Milky Way and other nearby galaxies--which control the rate of star formation and the dynamics of interstellar gas--arose from a slow "dynamo effect." In this process, slowly rotating galaxies are thought to have generated magnetic fields that grew very gradually as they evolved over 5 billion to 10 billion years to their current levels.
    But in the October 2 issue of Nature, the astronomers report that the magnetic field they measured in this distant "protogalaxy" is at least 10 times greater than the average value in the Milky Way.
    "This was a complete surprise," said Arthur Wolfe, a professor of physics at UC San Diego's Center for Astrophysics and Space Sciences who headed the team. "The magnetic field we measured is at least an order of magnitude larger than the average value of the magnetic field detected in our own galaxy."
    Complete Story
  • Fellow, American Academy of Arts and Sciences, 1995
  • Fellow, American Academy of Arts and Sciences, 1995
  • Chancellor's Associates Chair of Physics, 1997
  • Chancellor's Associates Chair of Physics, 1997
  • Sackler Fellowship, University of Cambridge, 2004-2007
  • Sackler Fellowship, University of Cambridge, 2004-2007
Selected Publications
  • - Rafelski, M., Wolfe, A. M., & Chen, H.-W., "Star Formation from DLA Gas in the Outskirts of Lyman Break Galaxies at z ~ 3", ApJ, 736, 48 (2011)

  • - Prochaska, J. X., & Wolfe, A. M "On the (Non)Evolution of H I Gas in Galaxies over Cosmic Time", ApJ, 696, 1542 (2009)

  • - Wolfe, A. M., Prochaska, J. X., Jorgenson, R. A., & Rafelski, M. "Bimodality in Damped Lyman Alpha Systems", ApJ, 681, 881 (2008)

  • - Wolfe, A. M., & Chen, H.-W., "Searching for Low Surface Brightness Galaxies in the Hubble Ultra Deep Field: Implications for the Star Formation Efficiency in Neutral Gas at z 3", ApJ, 652, 981 (2006)

  • - Wolfe, A.M., Gawiser, E., and Prochaska, J.X., "Damped Ly alpha Systems", ARAA, 43, 861 (2005)

  • - Wolfe, A.M., Prochaska, J.X., and Gawiser, E., "CII* Absorption in Damped Ly Systems. II. A New Window on the Star Formation History of the Universe", ApJ, 593, 235 (2003).

  • - Wolfe, A.M., Lanzetta, K.M., Foltz, C.B., and Chaffee, F.H., "The LBQS Survey for Damped Ly Absorption Systems", ApJ, 454, 698 (1995)

  • - Wolfe, A.M.,Turnshek, D.A., Smith, H.E., and Cohen, R.D., "Damped Lyman-Alpha Absorption by Disk Galaxies at Large Redshifts I: The Lick Survey", ApJ, 61, 249 (1986)

  • - Wolfe, A.M., Brown, R.L., and Roberts, M.S., "Limits on the Variation of Fundamental Atomic Quantities over Cosmic Time Scales", Phys. Rev. Lett, 27, 179 (1976)

  • - Sachs, R. K. and Wolfe, A. M. "Perturbations of a Cosmological Model and Angular Variations in the Microwave Background", ApJ, 147, 73 (1967)