Faculty Profile

John O'Meara, PhD

Professor of Physics
View Curriculum Vitae

Ph.D. University of California, San Diego
B.S. University of Washington

My research interests include, among other areas, Big Bang nucleosynthesis and light element abundances, Lyman limit and damped Lyman alpha systems, astrophysical properties of quasar absorption line systems, and galaxy-intergalactic medium interactions.

My primary research focus is to attempt to better understand the universe through the study of absorption lines seen in the spectra of high redshift quasars (or QSOs).  When we pass the light from any astronomical object through a spectrograph, it is broken into its constituent colors, producing a value for the intensity of the light as a function of the wavelength of the light.  Spectroscopy is a powerful tool with which we can learn what types of atoms astronomical objects are made of, what their energies are, and how they are moving relative to us on Earth.  In the case of QSO spectroscopy, the spectrum we see contains information about both the QSO and any material which happens to also lie along the line of site.  In my research, it is the intervening material which interests me. 

Awards:  Saint Michael’s Scholarship and Artistic Achievement Award, 2014

Elected to membership in the Vermont Academy of Science and Engineering, 2015

Appointed member to the Large Ultraviolet Visible Optical Infrared (LUVOIR) Surveyor Science and Technology Definition Team by NASA, 2016

With two colleagues at the University of California, Santa Cruz, I recently published an astronomical break-through discovery in Science, the premier journal for all science on November 10, 2011.

Using the giant 10-meter Keck I telescope in Hawaii, we have discovered two giant clouds of intergalactic gas whose chemical composition has been unaltered since the dawn of time. The clouds, located over 11 billion light years from Earth, offer direct supporting evidence for the Big Bang model of cosmology. Physics World magazine named it one of their Top 10 Breakthroughs for 2011 (number 10).


  • Crighton, N.M., O’Meara, J.M., & Murphy, M.T., 2016, MNRAS, 457, 44
  • Fumagalli, M., O’Meara, J.M., & Prochaska, J. X., 2016, MNRAS, 455, 4100
  • Dutta, R. et al. 2016, MNRAS, 456, 4209
  • Burchett, J.N. et al. 2015, ApJ, 815, 91
  • Prochaska, J.X., et al. 2015, ApJS, 221, 2
  • Cooke, J & O’Meara, J.M., 2015, ApJ, 812, 27
  • Cooper, T. J. et al. 2015, ApJ, 812, 58
  • O’Meara, J.M.  et al. 2015, AJ, 150,111
  • Crighton, N.M. et al. 2015, MNRAS, 452,217
  • Lusso, E. et al. 2015, MNRAS, 449, 4204
  • Fumagalli, M. et al. 2015, MNRAS, 445, 1745
  • Worsek, G. et al. 2014, MNRAS, 445, 1745
  • Fumagalli, M. et al. 2014, MNRAS, 444,1282
  • Werk, J.K. et al. 2014, ApJ, 792, 8
  • Lehner, N. et al. 2014, ApJ, 788, 119
  • Gaulthier, J-R et al. 2014, MNRAS, 439, 342
  • Oliveira, C.M. et al. 2014, ApJ, 783, 22
  • Prochaska, J.X. et al. 2014, MNRAS, 438, 476
  • Seyffert, E.N. et al. 2013, ApJ, 779, 161
  • Fox. A.J. et al. 2013, ApJ, 778, 187
  • Tumlinson, J. et al. 2013, ApJ, 777, 59
  • Fumagalli, M. et al. 2013, ApJ, 775, 78
  • Crighton, N.M. et al. 2013, MNRAS, 433,178
  • Lehner, N. et al. 2013, ApJ, 770, 138
  • O’Meara, J.M. et al. 2013, ApJ, 765, 137
  • Werk, J.K. et al. 2013, ApJS, 204,17
  • Cooksey K.L. et al. 2013, ApJ, 763, 37
  • Thom, C. et al. 2012, ApJ, 758,41
  • Fumagalli, M. et al. 2012, A&A, 545, 68
  • Werk, J.K. et al. 2012, ApJS, 198, 3
  • J.K. Werk et al.  2012 ApJS, 198,3
  • M. Fumagalli et al. 2011 Science, 334, 1245
  • J. Tumlinson et al. 2011 Science, 334, 948
  • R. Simcoe et al. 2011 ApJ 740,1
  • J. M. O'Meara et al. 2011 ApJS, 195,16
  • J. Tumlinson et al. 2011 ApJ, 733, 111
  • J. Meiring et al. 2011 ApJ, 532, 35
  • J. M. O'Meara et al. 2010, GCN 11089,1
  • J.X. Prochaska et al. 2010, ApJ, 532, 35
  • M. Fumagalli et al. 2010, MNRAS, 408, 362
  • G. Prochter et al. 2010, ApJ, 708, 122
  • J.X. Prochaska et al. 2009, ApJL, 705,113
  • The Interstellar Medium of Gamma-Ray Burst Host Galaxies. I. Echelle Spectra of Swift GRB Afterglows
  • J. X. Prochaska et al. 2007, ApJS, 168, 231
  • The Keck+Magellan Survey for Lyman Limit Absorption. I. The Frequency Distribution of Super Lyman Limit Systems
  • J. M. O’Meara et al.  2007, ApJ, 656, 666
  • The Deuterium-to-Hydrogen Abundance Ratio toward the QSO SDSS J155810.16-003120.0 J. M. O’Meara et al.  2006, ApJ...649L..61O
  • Supersolar Super-Lyman Limit Systems, J. X. Prochaska et al.  2006, ApJ...648L..97P
  • A Shot in the Dark: A Technique for Locating the Stellar Counterparts of Damped Lyα Absorbers
  • J. M. O’Meara et al.  2006, ApJ...642L...9O
  • Predicting QSO Continua in the Lyα Forest, N. Suzuki et al.  2005, ApJ...618..592S
  • Cosmological Parameters σ8, the Baryon Density Ωb, the Vacuum Energy Density ΩΛ, the Hubble Constant and the UV
  • Background Intensity from a Calibrated Measurement of H I Lyα Absorption at z=1.9
  • D. Tytler et al.  2004, ApJ...617....1T
  • H I Gas in Higher Density Regions of the Intergalactic Medium
  • T. Misawa et al. 2004, AJ....128.2954M
  • Cosmology from the high redshift intergalactic medium
  • J. M. O’Meara 2004, PhDT.......196O
  • The Kast Ground-based Ultraviolet Spectral Survey of 79 Quasi-stellar Objects at Redshift 2 for Lyα Forest and Metal Absorption
  • D. Tytler et al.  2004, AJ....128.1058T
  • The Cosmological Baryon Density from the Deuterium-to-Hydrogen Ratio in QSO Absorption Systems: D/H toward Q1243+3047
  • D. Kirkman et al.  2003, ApJS..149....1
  • Relative Flux Calibration of Keck HIRES Echelle Spectra
  • N. Suzuki et al. 2003, PASP..115.1050S
  • The UCSD HIRES/Keck I Damped Lyα Abundance Database. IV. Probing Galactic Enrichment Histories with Nitrogen
  • J. X. Prochaska et al.  2002, PASP..114..933P
  • The UCSD HIRES/Keck I Damped Lyα Abundance Database. III. An Empirical Study of Photoionization in the Damped Lyα System toward GB 1759+7539
  • J. X. Prochaska et al.  2002, ApJ...571..693P
  • The UCSD HIRES/Keck I Damped Lyα Abundance Database. I. The Data
  • J. X. Prochaska et al.  2001ApJS..137...21P
  • New Hubble Space Telescope Spectra of QSO PG 1718+4807: No Evidence for Strong Deuterium Absorption
  • D. Kirkman et al.  2001ApJ...559...23K
  • The Deuterium to Hydrogen Abundance Ratio toward a Fourth QSO: HS 0105+1619
  • J. M. O’Meara et al. 2001ApJ...552..718O
  • QSO 0130-4021: A Third QSO Showing a Low Deuterium-to-Hydrogen Abundance Ratio
  • D. Kirkman et al.  2000ApJ...529..655K
  • Review of Big Bang Nucleosynthesis and Primordial Abundances
  • D. Tytler et al.   2000PhST...85...12T
  • Deuterium and the baryonic density of the Universe.
  • D Tytler. et al.  2000PhR...333..409T

Observing the Stars

John O’Meara, professor of physics, learned last June (2017) from the Space Telescope Science Institute (STScI) in Maryland that 5 of 11 international team-science proposals that he is a part of – proposals requiring highly prized Hubble observation time -- had been granted as part of the telescope’s 25th, near-annual observational “Cycle” that is presently ongoing. Funding to analyze the data is part of it – more than $1 million to the teams he is on, with about $68,000 coming direct to St. Mike’s. Now the earliest data is starting to come in and the projects are hitting full stride, reports John, who also in December presented a lecture for the Environmental and Health Science Speaker Series, Fingerprints of the First Stars: Unraveling the Atomic History of the Universe” at Vermont’s Johnson State University.
(posted June 2018)

John O'Meara, professor and chair of physics, appears on the 'Deep Astronomy' Channel's 'How Do We Make Future Space Astronomy Missions Happen?' episode. John also presented an online-remote seminar for fellow scientists on behalf of NASA to help explain LUVOIR -- a mission concept for a space telescope to launch in the 2030s.  It would be significantly more powerful than the Hubble Space Telescope if selected to be constructed, and John is one of the Science team leads for the project. The Seminar series brings astronomers from multiple fields of study together to talk about what kind of science would be enabled with such an awesome machine. John says that his talk on June 21 was a general overview on the possibilities to do great galaxy science with LUVOIR. He also was cited by Forbes (on its Forbes Science web page) this fall in an article titled "New Space Telescope, 40 Times The Power Of Hubble, To Unlock Astronomy's Future,” in which the contributing author Ethan Siegel wrote: “I spoke with John O’Meara, the lead of Cosmic Origins Science for LUVOIR, about a wide variety of topics related to this proposed telescope. The piece proceeds to outline six things that such a telescope would allow us to learn, according to John. In August 2017 he was a guest on Vermont Public Radio's program Vermont Edition talking about the end of the 13-year Cassini mission to Saturn after a long journey that produced incredible images of the ringed planet. He also was a popular guest with local media this past August to provide his expertise on all matters relating to the rare solar eclipse. He spoke with Abbey Isaacs of Local NBC 5 news to provide tips on safe, creative and interesting ways to view or experience the phenomenon. Also, alumna reporter Elizabeth Murray '13  did a nice feature with John about the eclipse for the Burlington Free Press, and even took his photo near the College’s Observatory and posted a video from there for the paper's/website's August 17 edition. Also, as he was on his way out of town for some important international astronomical work, he found time to stop and tell reporter Priscilla Liguori from  WCAX Channel 3 about what to expect from the eclipse. “He also was quoted in an article on the science/tech website Gizmodo, on the topic of “brown dwarfs” that are nearly, but not quite, stars
(posted December 2017)

John O’Meara, professor and chair of physics, has been in typical great demand among physicists, journalists, other academics and the public. Some highlights in brief: He was an invited colloquium speaker at the University of Washington, his alma mater; for the science journal Gizmodo he was quoted at length about the future of the James Webb Telescope; he was invited speaker at the 2017 Space Telescope Science Institute Spring Symposium, April 2017, on the topic, “A Tale of Two Cities:  The Bimodal Metallicity Distribution of the Circumgalactic Medium”; he was quoted in the Christian Science Monitor about scientists’ fears over Trump Administration cutbacks as NASA plans a long-term climate mission; he was named to the Executive Committee of the Cosmic Origins Program Analysis Group (COPAG) for NASA; he was quoted in a Scholastic/New York Times Upfront online feature on a NASA twins study; he was an invited speaker for Keck observatory donors and presented an additional public lecture in Hawaii while there; he was Physics Colloquium speaker at both Middlebury and the University of Vermont; he was an invited review panelist for NASA; and, John has had four papers published in the Astrophysical Journal since November 2016.
(posted June 2016)

John O’Meara, associate professor and chair of physics, reports three new publications in recent months:  "MUSE searches for galaxies near very metal-poor gas clouds at z ˜ 3: new constraints for cold accretion models” in the Monthly Notices of the Royal Astronomical Society; also, “Low-Metallicity Absorbers Account for Half of the Dense Circumgalactic Gas at z ~1” in the Astrophysical Journal; and, “The Cosmic Evolution of the Metallicity Distribution of Ionized Gas Traced by Lyman Limit Systems,” also in the Astrophysical Journal. John also recently was an invited Physics Colloquium speaker at the University of Connecticut.
(posted November 2016)

John O’Meara, associate professor and chair of physics, was part of a team awarded over $500,000 in a grant from NASA to understand how galaxies spread heavy elements throughout the universe. He was appointed to the Large UltraViolet Optical InfraRed (LUVOIR) telescope Science & Technology Definition Team by NASA, has had a number of publications accepted in journal, was an invited speaker/participant at the ‘Maximizing Science in the Era of LLST’ workshop in Arizona and an invited colloquium speaker at Durham University in England; and, was a National-Science-Foundation-funded participant at the Thirty Meter Telescope Science Forum in Kyoto, Japan.
(posted June 2016)

John O’Meara, associate professor of physics, in July gave an invited presentation at the conference “The metal enrichment of diffuse gas in the universe” at the Sexten Center for astrophysics in Sesto, Italy. John also received confirmation that his paper ‘The First Data Release of the KODIAQ survey” was accepted in the Astronomical Journal. In August, John learned he was elected to the Vermont Academy of Science and Engineering -- only the second Saint Michael’s professor ever to have been so elected.
(posted September 2015)

John O’Meara, associate professor of physics, on February 27 was the invited colloquium speaker at the Max Planck Institute for Astronomy in Heidelberg, Germany, where he shared recent research developments in his work on galaxies and their environments. In February, he also was selected as a member of the International Science Definition Team for the 30-meter telescope project. In early April, John was the colloquium speaker (addressing an entire department or larger audience as opposed to a research seminar talk) at Middlebury and University of Vermont in celebration of the 25th anniversary of the launch of Hubble Space Telescope.
(posted April 2015)

John O’Meara, associate professor of physics, has been named to the Committee on Astronomy and Public Policy for the American Astronomical Society. In March, John traveled to Rome and presented a poster at the “Science with the Hubble Space Telescope IV” conference.
(posted August 2014)

John O’Meara, associate professor of physics, presented two talks at the meeting of the American Astronomical Society in Washington, D.C., early in January. The talks were "Large Reservoirs Of Metal-Poor Gas Around z<1 Galaxies” and, "OVI as an Unique Tracer of Large-Scale Stellar Feedback at 2<z<4” He also appeared on five posters: "High-z QSO Absorption Systems: Metal-Poor Cold Flows and Mg II Absorber Host Galaxies,” "Metallicities of Extraplanar H II Regions in Edge-on Spiral Galaxies,” “The Metallicity Distribution of the Circumgalactic Medium at z < 1 Traced by Lyman Limit Systems,” “The First Detection of Deuterated Molecular Hydrogen at z < 1.7 Beyond the Milky Way Galaxy,” and "The High-Ion Content and Kinematics of Low-Redshift Lyman Limit Systems.” (March 2014)

John O'Meara, associate professor of physics, has been named a visiting Fellow at the Swinburne University of Technology in Melbourne, Australia next year.  That university is sponsoring John to engage in collaborative research for a month at Swinburne, spread over two visits of two weeks, once in June, once in November.  The visiting fellow position is one that is competed for internationally every year. (November 2013)

October 2013

Talking telescopes (and visiting them)

If you wave down John O'Meara, the college's resident astronomer genius, as he dashes across the Saint Michael’s campus green from Cheray Science Hall to the Post Office, he might tell you about telescopes - big ones, little ones, near and far.

"I was just in Chile at Las Campanas Observatory, and the second night - October 6 - was the best observing conditions I've ever had on the ground - ever," he says of coveted time that he applies for and frequently is awarded at the world's best and most powerful telescopes. He collects data at such sites for his ongoing study of galaxy formation, and is an oft-published and respected leader in his specialty field. Once or twice a year each, O'Meara says, he'll head either to Las Campanas, or to Hawaii's Keck Observatory, where in recent years he was able to take a student to collect data for a class project she was doing with him.

Though no students made it to Chile this trip, "my physics students got to enjoy a Tegrity session over the computer from the summit," he says, referring to the college's high-tech audio-visual teaching resource called Tegrity, and to the mountaintop location of Las Campanas. "They got to actually see me there - a silly video of me running under the primary mirrors to give them a sense of scale.”

O'Meara says he might use data he gathered in Chile for future astronomy classes, though it's hard to say exactly how until the information gets processed. "The data we took was superb in quality because the sky was so good. Whether that translates into a scientific discovery remains to be seen, but the raw data is as good as it can get from the ground," he says. The physics professor says he's already booked for a January trip to Hawaii to use the Keck for more observations. "The Chile telescope I just used is the best ground-based telescope for imaging - the Keck is the biggest boy in town and hard to beat with the technology and size - but if you want to take pictures of the sky, as I was doing, it's better on the average in Chile."

Such far-flung, cutting-edge technology in optimal observing conditions is a far cry from the college's own astronomical facility, the Holcomb Observatory - a small and curious-looking red-brick domed building that sits alone and mostly unvisited in a field near the Fire and Rescue Station across from main campus. But its telescope still works, O'Meara says, and he’s been known to take classes out there every so often.

Despite some drawbacks, it's a great resource, he says. "It's right near Route 15 with all the passing lights, and there's the night lights of Burlington on the horizon, plus it has giant trees back behind it, so the view is obfuscated in several major ways, but it still functions. So I take students at night to look at the sky - the moon, planets."

"It would be nicer if we even could just drop the observatory in the Mount Mansfield-facing field down from the rocks around the corner, or better yet, put the telescope on top of a building somewhere, but I guess that's not happening," he says. Perhaps, he allows, a system could be rigged to let students know when he's going to be at the Holcomb so they can come and view the sky when viewing is best - an "Observatory Webcam" might even be feasible, he says.

As a sidebar to that notion, he shares a bonus tip about better directing and thereby improving the strength of wireless router signals, either by using Pringles potato chip cans or by cutting a beer can in half and mounting the pieces on the bunny ears. "Pro tips!" he says.

professor John O'Meara at Las Campanas Observatory 

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