Second Year of Cal Poly Astronomy Fellowship to Examine High-Energy Particle Jets Near Supermassive Black Holes



Cal Poly working with the VERITAS International Collaboration to study gamma rays

Courtesy Jodi Christiansen

Mary Kertzman (DePauw University physics professor), Cal Poly students Connor Poggemann (physics) and Will Root (aerospace engineering) and Jodi Christiansen (Cal Poly physics professor) stand in front of one of the VERITAS telescopes.

­In the second year of the Astronomy Faculty Research Fellowship in Cal Poly’s Bailey College of Science and Mathematics, a research team will study extremely high-energy photons emitted by the extreme environment found near mega-sized black holes.

The fellowship was launched in 2023 through a generous donation from the Marrujo Foundation, established by Cal Poly alumnus Daniel Marrujo and his wife, Rosamaria, covering three years of the program.

The fellowship allows faculty to focus more closely with students on scientific research, offering them cutting-edge experiences as researchers.

Physics Professor Jodi Christiansen, the 2024 faculty fellow, is working with the VERITAS International Collaboration, part of the Center for Astrophysics, Harvard and Smithsonian, to study very-high-energy photons, or gamma rays, emitted by particles shooting down an astrophysical jet associated with supermassive black holes. Gamma rays are produced by the hottest and most energetic objects in the universe, such as neutron stars and pulsars, supernova explosions and regions around black holes.

Black holes, an area of such immense gravity that not even light can escape from it, sucks in just about anything in its proximity, but some of that matter can escape as high-speed jets of particles and radiation. The accretion disk, a massive field of gas, dust, asteroids and other matter swirling at massive speed around a black hole’s outer boundaries, wouldn't exist without black holes, typically formed by the death of a massive star. The disk produces X-rays and optical infrared and radio electromagnetic radiation that reveals the black hole’s location. Some of this material is vacuumed into the black hole, while other parts may be forced out as jets.

VERITAS, or Very Energetic Radiation Imaging Telescope Array System, gathers data from the night sky using a set of four, 12-meter telescopes in southern Arizona at the Fred Lawrence Whipple Observatory. The facility, owned and operated by the Smithsonian Astrophysical Observatory, enables research activities using gamma-ray and cosmic-ray astronomy.

The observatory is near Amado, Arizona, about 40 miles south of Tucson, on 8,553-foot Mount Hopkins. Christiansen's work has included trips to the site for research and viewing opportunities, as well as analyzing computer-based imaging remotely.

“These gamma rays are extremely energetic, so much so that they can't come from a hot star, which just isn’t energetic enough,” Christiansen said. “What we’re looking at comes from the environment near a supermassive black hole.”

The plasma particles that the Cal Poly team observes come from an environment that is so powerful that the “atoms have fallen apart,” Christiansen said.

Most galaxies have a supermassive black hole at their center, Christiansen said, and some release energy in the form of enormous blasts of particle streams.

“Our images have shown jets that are bigger than galaxies,” she said. “This jet structure is huge compared to the galaxy. There aren’t a lot of places in space that produce this level of energy."

Christiansen said that the high-energy gamma rays that reach Earth offer insights into the density and magnetic properties of the plasma very close to the supermassive black hole.

“There’s still a lot to learn about the physical mechanisms that produce the jets,” Christiansen said. “We don’t know why jets are formed. But we are very interested in how that energy can be released from this environment around the black hole.”

Her Cal Poly research teams, in recent years, have been active in discovering blazars, which are streams of high-energy electromagnetic radiation that are directed at an angle that points toward the earth.

A few years ago, Christiansen developed a software algorithm for a VERITAS telescope that improves the resolution of the device by about 25% — and also allows scientists to detect signals with 30% less observing time, enhancing the ability to discover rare blazars and other astronomical phenomena.

The first year of the Marrujo fellowship was led by Elizabeth Jeffery, a Cal Poly assistant professor of physics, who explored data related to locations and brightness of stars to better understand how long they’ve existed. Jeffrey’s work focused on white dwarf stars, which represent the endpoint of a low mass star’s life.

The Marrujo Foundation supports and works with educational institutions to further research in astronomy, astrophysics and cosmology to establish a world-leading fellowship ecosystem. The foundation’s efforts aim to ensure that institutional work challenges current understanding of space, creates new opportunities and makes a difference in people’s lives across the U.S. and around the globe.

“The inaugural year of this program has been an amazing journey marked by success, profound insights, and captivating discoveries," said Daniel Marrujo, who earned a master’s degree in materials engineering and a bachelor’s degree in electrical engineering with a minor in physics from Cal Poly. "Dedicated to offering cutting-edge research and educational training to Cal Poly students, our commitment resonates with the essence of advancing the Learn by Doing mission and nurturing the future cohort of extraordinary astronomers and scientists.”

“The Marrujo Foundation is filled with absolute delight as we witness the flourishing landscape of Cal Poly astronomy, and we eagerly anticipate the unfolding of remarkable accomplishments yet to come,” he added.

Marrujo is the former chief strategy officer and former director of the Office of Research and Technology Applications at the Defense Microelectronics Activity, delivering microelectronics solutions to the U.S. Department of Defense. He is the president and managing director at Sacramento-based Trusted Strategic Solutions, LLC, working with commercial, civil and national security entities to provide the foresight and expertise that ensures safety, time savings, and financial protections.  

EurekAlert!, the online, global news service operated by AAAS, the science society.