Scientific Interests:

High-energy Astrophysics
Astroparticle Physics
Dark Matter
Particle Physics

Recent Research Highlights:

  • The Science with CTA document released. The exciting science program to be carried out by CTA has been put forward in detail in a 200-page document Science with the Cherenkov Telescope Array. This science program was developed over a period of more than five years by hundreds of scientists in the CTA Consortium. The first version of the document was uploaded to the arXiv archive by Rene Ong on 23 September 2017. For more details, see the Press Release on the main CTA web site.
  • GAPS balloon experiment approved by NASA . In early 2017, NASA approved funding for the GAPS project to enter the construction phase of the experiment. With funding also available in Japan and Italy, the GAPS team is now working towards the final design and construction of the GAPS science payload. The integration of the payload is scheduled for late 2019 with a first possible science flight during the 2020-2021 Antarctic season. See the GAPS website for more details.
  • 2015-2016: Progress on the Cherenkov Telescope Array (CTA). Consisting of two large arrays of atmospheric Cherenkov telescopes, CTA will explore the very high energy (VHE) universe with unprecedented sensitivity. During the last year, the design and development of the baseline observatory made great progress. For an overview of the science of CTA and its current status, see a recent article by Liz Kruesi for Symmetry magazine. An article by Edwin Cartlidge for Science magazine discusses the recent selection of the two proposed locations for the CTA sites.
  • Rene Ong elected Co-Spokesperson of the Cherenkov Telescope Array (CTA) Consortium. In September 2014, at a CTA meeting in Catania, Italy, Rene Ong was elected Co-Spokesperson of the CTA Consortium. Consisting of over 1,200 scientists from 200 institutions in 29 countries, the CTA Consortium was formed to design and help construct CTA and to carry out scientific investigations with CTA to explore the VHE universe in the decade of 2020 to 2030. More details on CTA and its science goals can be found at the general CTA public website.
  • Update on the Cherenkov Telescope Array. The year 2015 was an important one for CTA with a successful Critical Design Review (CDR) and the selection of the observatory sites. An article by Kelen Tuttle in Symmetry magazine provides a good summary of recent activities and the site selection process.
  • Workshop on Anti-deuterons in the Cosmic Rays. Anti-deuterons have never been detected in the cosmic rays, but their presence could have major implications for new physics, including modiels of dark matter and primordial black holes. Rene Ong and Philip von Doetinchem (U. Hawaii) organized a workshop at UCLA in June 2014 to explore the science of anti-deuterons, both from the theoretical and experimental perspective. The workshop was entitled Antideuteron 2014.
  • Update on the Cherenkov Telescope Array. CTA is a major ground-based gamma-ray telescope project that is under development. CTA plans to construct two large arrays of atmospheric Cherenkov telescopes, one to be installed in the northern hemisphere and one in the southern hemisphere. UCLA is actively working on the site characterization and evaluation studies and is helping to propose two possible sites for the northern array of CTA in Arizona, USA. One proposed site is located 70 km east of Flagstaff, AZ, near Meteor Crater; the other proposed site is located 150 km west of Flagstaff, AZ, on Yavapai Ranch. See the recent article by Elizabeth Gibney in Scientific American that summarizes the present situation. There is also an earlier article on CTA site selection in Science magazine by Nuno Dominguez and a nice article describing the scientific motivation for CTA in Nature magazine by Eugenie Reich.
  • Successful flight of the prototype GAPS (pGAPS) balloon experiment. GAPS is a proposed experiment to search for anti-deuterons in the cosmic rays. These particles have never been detected astrophysically but would provide strong evidence for the annihilation of WIMP dark matter. The GAPS team, consisting of ~20 scientists in the US and Japan, designed and constructed a prototype instrument (pGAPS) to verify many of the key design elements of GAPS. After integration in the US, pGAPS was launched in June 2012 by the Japanese space agency (JAXA) from their balloon facility in eastern Hokkaido, Japan. A very successful, six-hour flight followed, as documented on the GAPS website and in a paper written by UCLA postdoc S. Isaac Mognet. The team is now proposing to build the full GAPS instrument for flight from NASA's balloon launch facility at the McMurdo Station in Antarctica.
  • VERITAS detects gamma rays above 100 GeV from the Crab Pulsar. The Crab, the remnant from a supernova explosion seen on Earth in 1054, is a famous object in astronomy. Ground-based observatories have detected very high energy (VHE) gamma-ray emission from the Crab for more than two decades, but these (unpulsed) detections were from the Crab Nebula. It has always been a dream to detect VHE emission from the pulsar itself. Based on more than 100 hours of data, VERITAS made the first detection of the Crab Pulsar above 100 GeV. The result, reported in a paper published in Science, indicates a completely new, and unexpected, component of radiation and does not fit within standard pulsar models. The VERITAS detection was highlighted by many science blogs and was covered in a NSF press release and was the subject of a nice article written by Kim DeRose of the UCLA press office.
  • VERITAS discovers VHE gamma rays from the Tycho supernova remnant . The Tycho supernova remnant (SNR) derives from the Type 1a supernova seen on Earth in 1572. As one of only a handful of historical supernovae, Tycho is a very important source in the history of astronomy. The Tycho SNR has been deeply studied and is one of the best understood remnants. Thus, it was always a prime target for observation by northern hemisphere atmospheric Cherenkov telescopes, such as VERITAS. The VERITAS detection came from deep observations made between 2008 and 2010 and are reported in a paper published in Astrophyical Journal Letters. Following the discovery by VERITAS, Tycho was detected at GeV energies by Fermi. Of key importance is that the resulting gamma-ray spectrum from the lowest energies detected by Fermi to the highest energies detected by VERITAS strongly support a cosmic ray (proton) origin for the observed gamma-ray emission, as discussed in this paper.
  • Fermi detects gamma tays from the binary source Cygnus X-3. Cygnus X-3 is a rather famous X-ray object that was "discovered" as a soure of TeV and even PeV gamma rays in the 1970's and the 1980's. In fact, these discoveries accelerated the growth of the field of VHE astronomy. In the 1990's and 2000's, Cygnus X-3 was not firmly detected by any gamam-ray telescope, leading to speculation that the original results were statistical fluctations. Now, recent observations by the Large Area Telescope (LAT) of the Fermi Gamma-ray Space Telescope show a clear detection of Cygnus X-3, where the gamma-ray signal is correlated with the 4.8 hour orbital period of the binary system. Contributing to the LAT analysis were two UCLA undergraduates, Nickolas McColl and Laura Marchand, and this work contributed to a paper published in Science.
  • VERITAS makes the first detection of gamma rays from a starburst galaxy (M82). This discovery provides important clues towards understanding the origins of cosmic rays. Read the journal article in Nature. Popular articles can be found at 7th Space, at, in the CERN Courier, at the National Science Foundation Website, and in the UCLA newsroom.
  • VERITAS discovers VHE gamma rays from a powerful blazar 1ES 0502+675. This source is one of the most distant objects known to emit TeV gamma rays. Since TeV photons are expected to be absorbed by intergalactic radiation fields, this discovery is surprising because it implies that the Universe is more transparent at these energies than expected. Indeed, there are speculations that some sort of new physics may be involved. The discovery was announced in an Astronomical Telegram. Rachel Courtland wrote a nice article in the New Scientist on the possible existence of axion-like particles to explain the observations.

Experimental Program:

Very Energetic Radiation Imaging Telescope Array System (VERITAS)
VERITAS is state-of-the-art observatory of very high-energy (VHE) gamma rays in the energy range between 50 GeV and 50 TeV. VERITAS consists of four large (12m diameter) reflectors, each viewed by a camera of 500 photomultiplier tubes. Each tube is read out by a 500 MHz Flash-ADC. The VERITAS construction took place between 2003 and 2007, with the full four-telescope array starting operations in September 2007. VERITAS has produced many scientific results so far, including the detection of more than VHE gamma rays from a wide variety of astrophysical sources, including pulsar wind nebulae, supernova remnants, binary systems, active galactic nuclei, and starburst and radio galaxies, and very sensitive limits on the annihilation of WIMP dark matter. In VERITAS, UCLA has primary responsibility for the Level 1 Trigger, the Level 3 (multi-Telescope) Trigger, and the online data storage and archiving facility. Scientists at UCLA are involved in a broad range of scientic topics, including Galactic sources, extragalactic sources, dark matter, and astroparticle physics.

Cherenkov Telescope Array (CTA)
CTA is a future, major gamma-ray observatory that would greatly expand our understanding of the high-energy and very high-energy universe. Currently in the development phase, CTA could consist of two arrays of atmospheric Cherenkov telescopes spread out over a large area. One array will be built in the southern hemisphere and the other in the northern hemisphere. CTA would be a logical follow-up to the VERITAS and Fermi missions that are currently operational. UCLA is involved in many aspects of CTA, including: overall leadership of the project, development of the Schwarzschild-Couder, Telescope (SCT), site evaluation and site development, and science planning and simulations.

General AntiParticle Spectrometer (GAPS) Experiment
GAPS is a proposed balloon-borne experiment to search for anti-deuterons in the cosmic rays. Anti-deuterons at energies below 1 GeV are a unique signature of annihilating weakly-interacting dark matter. GAPS will consist of a large array of Si(Li) detectors surrounded by a time of flight (ToF) detector. A prototype instrument (pGAPS) was successfully flown in 2012. The GAPS team is now proposing for the full science instrument to be flown in Antarctica. UCLA is responsible for elements of the time-of-flight, trigger, and electronic systems.

Fermi Gamma-ray Space Telescope
Fermi is a high-energy gamma-ray satellite launched by NASA on June 11, 2008. The Large Area Telescope (LAT) on Fermi has an energy range between 10 MeV and 300 GeV. The LAT consists of silicon strip detectors for tracking and a CsI calorimeter for energy measurement. Fermi is fully operational with many exciting results so far and more to come. Ong has been an Associate Member of the LAT since its inception.

Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), Now Completed
STACEE used the atmospheric Cherenkov technique to detect gamma rays at energies between 50 and 500 GeV. Until recently, this energy range was not explored by any other experiment. In 1999, a early version of STACEE detected ~4,800 high-energy gamma rays from the Crab Nebula, and in 2001, rapid flares of gamma rays were detected from the blazar Markarian 421. Operating between 2001 and 2007, STACEE carried out a comprehensive program of observations of galactic and extragalactic sources. In 2006, STACEE reported spectral measurements of the Crab Nebula and Markarian 421 at energies between 150 GeV and 1500 GeV. In 2009, STACEE reported results from observations of 23 gamma-ray bursts, the pulsar PSR 1951+32, and the Draco dwarf galaxy. UCLA was the lead university on STACEE.

Research Group (as of January 2018):

Ralph Bird, Postdoctoral Scholar,
Isaac Mognet, Research Associate, (now at Penn State University)
Sean Quinn, Postdoctoral Scholar,
Jeffrey Zweerink, Research Physicist,

Matt Buchovecky, Graduate Student,
Jamie Ryan, Graduate Student,

Takeru Hayashi, Undergraduate Students,


Post-docs and students who have worked with me (their last known location and position):

Former Post-Docs (chronological)

Corbin Covault Case Western Reserve University, Professor
Kevin Green University of Connecticut-Stamford, Physics Instructor
Brian Fick Michigan Technical University, Professor
Lucy Fortson University of Minnesota, Professor
Mark Chantell University of Chicago, Teaching Staff
Zoa Conner College of Southern Maryland, Yoga Instructor
Jim Hinton Max Planck Institute fur Kernphysik, Director
Jeffrey Zweerink UCLA, Research Physicist (part-time)
Amanda Weinstein Iowa State University, Associate Professor
Pratik Majumdar Saha Institute of Nuclear Physics (SINP), Associate Professor
Taylor Aune The Climate Corporation, Scientific Software Engineer

Former Graduate Students (chronological)

Joseph Fowler National Institute of Standards and Technology (NIST), Senior ARRA Fellow
Scott Oser University of British Columbia, Professor and Canada Research Chair
Jennifer Carson Santa Monica College, Professor
Alex Jarvis Selection Studios, Analyst
Ozlem Celik-Tinmaz Accenture Analytics, Data Science Manager
Yeuk Chun (Ken) Chow (Financial sector)
Alexis Popkow University of Hawaii, Postdoctoral Fellow

Former Undergraduates (chronological, from 1990-present)

Peter Burke University of California, Irvine, Professor
Sunil Golwala California Inst. of Technology, Professor
Peter Rauske TradeLink, Research Analyst
Zandra Wells (now Kelley) Greater Lawrence Family Health Center, MD
Hugh Kim Greyson Capital Management, Managing Partner
Matthew Pritchard Cornell University, Professor
Antonino Miceli Argonne National Laboratory, Physicist
Thomas Brennan Ferris State University, Professor
Dan Schuette Lincoln Laboratories, M.I.T., Technical Staff Member
Eugene Chae Vista Consulting Group, Software Developer
Nicolas Rassat Ecole Polytechnique, Graduate Student (last known location)
Susan Channels Costa Mesa, CA, CPA
Jason Minamora California Inst. of Technology, Graduate Student (last known location)
Katy Tschann-Grimm Lancaster University, Senior Research Associate
Thomas Fishman MTV, Vice President, Content Marketing & Fan Engagement
Jeffrey Dunworth University of California, San Diego, Graduate Student
William Gignac Ecole Polytechnique, Postdoctoral Researcher
Cyrus Rustomji South 8 Technologies, Inc., Chief Technology Officer
Jennifer Helsby Freedom of the Press Foundation, Ford-Mozilla Open Web Fellow
Jennifer Sierchio MIT Lincoln Laboratory, Associate Staff
Daniel Margala Silicon Valley Data Science, Data Scientist
Nickolas McColl University of California, Los Angeles, Postdoctoral Research Associate
Laura Marchand ME Engineers, Inc., Associate
Jacob Schwartz Princeton University, Graduate Student
Brandon Maupin Private industry, Los Angeles area
Richie Nagi Continental AG, Electro-Optics Engineer
Erika Zetterlund University of Colorado, Graduate Student
Sabrina Hong Rigetti Quantum Computing
Eylene Pirez UCLA, Graduate Student
William Johnson Halstrom Academy, Science Teacher
Shuoguang Liu University of Chicago, Graduate Student


My current research is supported by the National Science Foundation, the Department of Energy (Office of Science), NASA, and UCLA. I have also received support from the Sloan Foundation and the Grainger Foundation.