Faculty Directory

Department Chair: Jonathan Fortney Department Manager: Alyssa Danielli
Vice Chair: Brant Robertson Graduate Advisor: Brandon Day
Graduate Program Director: Andrew Skemer Department Assistant: Kali Lucas
Undergraduate Program Director: Connie Rockosi Astronomy Program Coordinator: Lani Skelton
J. Xavier Prochaska
  • Title
    • Professor
  • Division Physical & Biological Sciences Division
  • Department
    • Astronomy & Astrophysics Department
    • UC Observatories
  • Phone
  • Email
  • Website
  • Office Location
    • Interdisciplinary Sciences Building, 359
    • ISB 359
  • Mail Stop UCO / Lick Observatory
  • Mailing Address
    • 1156 High St
    • Santa Cruz CA 95064
  • Faculty Areas of Expertise Astronomy, Astrophysics, Oceanography

Summary of Expertise

In astrophysics, my primary expertise is spectroscopy -- dissecting the light emitted by distant sources (galaxies, quasars, transient phenomena) -- to examine the physical properties and processes driving the formation of our universe.  

Another passion and area of expertise is the application of artificial intelligence to pursue science in large astronmoical and oceanographic datasets.

Research Interests

My research examines the nature of gas both within and outside of galaxies, primarily during the first few billion years of the universe. The analysis relies on high resolution spectroscopy of distant, intrinsically bright sources (quasars, gamma-ray bursts). In this manner, we use the absence of light to study the metallicity, molecular fraction, depletion, ionization state, and velocity fields of gas in the young universe....  These (primarily) observatonal studies impact our understand of galaxy formation, cosmology, and (occasionally) fundamental physics.


I have  also led follow-up studies of transient and bursting sources (gamma-ray bursts, fast radio bursts) to provide unique insight into the gas within galaxies and beyond.  Recently, we have used fast radio bursts to resolve the so-called "missing baryons problem" a 20 year old challenge to detect the majority of normal matter in our universe at present times.

In addition to astrophysics, I am pursuing research in physical oceanograph (and am an affiliate of the Ocean Sciences department).

Biography, Education and Training

Xavier is a New England transplant and graduate of Physics from Princetion University (1993).  He moved to Californiate to pursue a PhD in Physics at the University of California,  San Diego (1998).  Prochaska was then a postdoctoral  Carnegie+Hubble Fellow at Carnegie Observatories from 1999-2002 before joining the faculty at UC Santa Cruz and as an astronomer at the Univeristy of California Observatories.

In 2020, I became an affiliate of the Ocean Sciences Department at UC Santa Cruz.

Honors, Awards and Grants


2023 -- Simons Pivot Fellowship

2020 -- AAAS Newcomb Cleveland Prize

2020 -- Distinguished Professor (UCSC)

2017 -- Outstanding Faculty Award (Division of Physical and Biological Sciences)

2010 -- Humboldt Fellow


Prochaska has received extramural funding from the National Science Foundation, NASA, the Smithsonian, and private donors and foundations to support his research over the past two decades.

Selected Publications

ADS search on Prochaska, J.

Teaching Interests

Currently, my research intersetes lie in two areas:  (1) experiential based training in observational astronomy and (2) applying statisitcal techniques inlcuding machine learning algorithms to analyze large and/or complex datasets.